Note: Descriptions are shown in the official language in which they were submitted.
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IMPLANTABLE DELIVERY DEVICE WITH SELF ADJUSTABLE EXIT PORT
This is a divisional application of Canadian
Application No. 2,284,929, based on International PCT
Application No. PCT/US98/04637 filed March 10, 1998.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to an
implantable delivery device, and more particularly to an
exit port, such as a slit orifice for an implantable osmotic
delivery device which has a variable size.
2. Description of the Related Art
Controlled delivery of beneficial agents such as
drugs in the medical and veterinary fields has been
accomplished by a variety of methods. One approach for
delivering a beneficial agent involves the use of
implantable diffusional systems. For example, subdermal
implants for contraception are described by Philip D. Darney
in Current Opinion in Obstetrics and Gynecology, 1991,
3:470-476. Norplant requires the placement of 6
levonorgestrel-filled silastic capsules under the skin.
Protection from conception for up to 5 years is achieved.
The implants operate by simple diffusion, that is, the
active agent diffuses through the polymeric material at a
rate that is controlled by the characteristics of the active
agent formulation and the polymeric material.
Another method for controlled prolonged delivery
of a beneficial agent involves the use of an implantable
osmotic delivery system. Osmotic delivery systems are very
reliable in delivering the beneficial agent over an extended
period of time. The osmotic pressure generated by an
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osmotic pump also produces a delivery rate of the beneficial
agent into the body which is relatively constant as compared
with other types of delivery systems.
In general, osmotic delivery systems operate by
S imbibing fluid from the outside environment and releasing
corresponding amounts of the beneficial agent. Osmotic
delivery systems, commonly referred to as "osmotic pumps",
generally include some type of a capsule having walls which
selectively pass water into an interior of the capsule which
contains a water-attracting agent. The absorption of water
by the water-attracting agent within the capsule reservoir
creates an osmotic
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1 pressure within the capsule which causes the beneficial agent to be
delivered from
2 the capsule. The water-attracting agent may be the beneficial agent
delivered to the
3 patient, however, in most cases, a separate agent is used specifically for
its ability to
4 draw water into the capsule.
When a separate osmotic agent is used, the osmotic agent may be separated 6
from the beneficial agent within the capsule by a movable dividing member or
7 piston. The structure of the capsule is such that the capsule does not
expand when
8 the osmotic agent takes in water. As the osmotic agent expands, it causes
the
s movable dividing member or piston to move, which in turn causes the
beneficial
agent to be discharged through an orifice at the same volumetric rate that
water
11 enters the osmotic agent by osmosis.
12 The orifice controls the interaction of the beneficial agent with the
external
13 fluid environment. The orifice serves the important function of isolating
the
14 beneficial agent from the external fluid environment, since any
contamination of the
beneficial agent by external fluids may adversely affect the utility of the
beneficial
is agent. For example, the inward flux of materials of the external fluid
environment
17 due to diffusion or osmosis may contaminate the interior of the capsule,
1a destabilizing, diluting, or otherwise altering the beneficial agent
formulation.
19 Another important function of the orifice is to control or limit
diffusional flow of the
2o beneficial agent through the orifice into the external fluid environment.
21 In known delivery devices, these functions have typically been performed by
22 flow moderators. A flow moderator may consist of a tubular passage having a
23 particular cross sectional area and length. The cross sectional area and
length of the
24 flow moderator is chosen such that the average linear velocity of the
exiting
beneficial agent is higher than that of the linear inward flux of materials in
the
26 external environment due to diffusion or osmosis, thereby attenuating or
moderating
27 back diffusion and its deleterious effects of contaminating the interior of
the osmotic
28 pump.
29 In addition, the dimensions of the flow moderator may be chosen such that
so the diffusive flux of the beneficial agent out of the orifice is small in
comparison to
31 the convective flux. Figure 1 is a graph showing the relationship between
the
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1 orifice dimensions and drug diffusion as a percentage of pumped or
connective
2 delivery for one set of pumping rates and drug diffusivity. Figure 1 shows,
for
3 example, that the diffusive flux of the beneficial agent can be kept to less
than 10%
4 of the convective flow using an orifice having a diameter of 5 mils and a
length of at
least 0.6 cm, or an orifice having a diameter of 10 mils and a length of at
least 2.4
6 cm.
7 One problem with flow moderators, however, is that the passage may
8 become clogged or obstracted with particles suspended in the beneficial
agent or in
s fluid from the external environment. Such clogging may be reduced or
eliminated
by increasing the diameter of the passage to 5 mil or more, for example.
However,
11 as shown in Figure 1, this increase results in a greater rate of diffusion
of the
12 beneficial agent out of the osmotic pump. A corresponding increase also
occurs in.
13 the back diffusion of the external fluid into the osmotic pump which may -.
14 contaminate the beneficial agent and adversely affect the desired delivery
rate of the
beneficial agent. Tolerances during fabrication also frequently dictate that
the
16 orifice diameter be greater than about 5 mils.
17 Systems with a long straight flow moderator are also impractical for
18 implantation applications because they increase the size of the implant
significantly
19 making the system difficult to implant.
Current flow modulators also cause separation of beneficial agents which
21 contain suspensions of bioactive macromolecules (proteins, genes, etc.).
When such
22 suspensions pass along a restriction in current flow modulators, the
suspension
23 separates and the delivery concentration of bioactive macromolecules
varies.
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SUNMARY OF THE INVENTION
According to one aspect of the invention, there is
provided a delivery device comprising: a capsule comprising
a chamber containing a beneficial agent to be delivered; a
flexible member having therein a slit orifice which is in
fluid communication with an interior of the chamber, the
flexible member comprising: a first portion upstream of the
slit orifice, the first portion having a cone-shaped recess;
and a second portion in which the slit orifice is located;
and means for applying a pressure to the beneficial agent to
force the beneficial agent through the recess and the slit
ori f ice .
According to another aspect of the invention,
there is provided a method of forming a delivery device
comprising the steps of: filling a chamber of the delivery
device with a beneficial agent having a known viscosity;
providing an exit passage through which the beneficial agent:
is delivered, the exit passage comprising a first portion
having a wall which is at an angle to a direction of flow of
the beneficial agent, the exit passage also comprising a
slit orifice downstream of the first portion; and selecting
the angle of the wall with respect to the direction of flow
of the beneficial agent based on viscosity of the beneficia].
agent.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and other objects, features and
advantages of the present invention will be more readily
understood upon reading the following detailed description
in conjunction with the drawings in which:
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Figure 1 is a graph of drug diffusion as a
function of the diameter and length of the orifice of a
delivery device;
Figure 2 illustrates a delivery device which
includes a slit orifice according to an exemplary embodiment;
of the invention;
Figure 3 illustrates a delivery device which
includes a slit orifice and a
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1 catheter according to another embodiment of the invention;
2 Figure 4 is a graph which shows the release rates of the delivery devices of
3 Figures 2 and 3 as a function of time;
4 Figure 5 illustrates a delivery device which includes a slit orifice and a
conical recess according to another embodiment of the invention;
6 Figure 6 is a graph which shows the release rate of the delivery device of
7 Figure 5 as a function of time;
8 Figure 7 illustrates a delivery device which includes a slit orifice and a
rigid
9 inner cylindrical member according to another embodiment of the invention;
Figure 8 illustrates a delivery device which includes a plurality of slit
orifices
11 according to another embodiment of the present invention; and
12 Figure 9 is a graph illustrating a comparison of the release rates of two
13 osmotic delivery devices having an orifice according to one embodiment of
the
14 present invention with the release rates of two osmotic delivery devices
having a
spiral flow moderator.
16
17 DESCRIPTION OF THE PREFERRED EMBODIMENTS
18 Definitions
19 The term "beneficial agent" includes any physiologically or
pharmacologically active substance or substances optionally in combination
with
21 pharmaceutically acceptable carriers and optionally additional ingredients
such as
22 antioxidants, stabilizing agents, permeation enhancers, etc.
23 The term "impermeable" refers to a material that is sufficiently
impermeable
24 to environmental fluids as well as ingredients contained within the
dispensing device
such that the migration of such materials into or out of the device through
the
26 iunpermeable material is so low as to have substantially no adverse impact
on the
= 27 function of the device.
28 The term "semipermeable" refers to a material that is permeable to external
29 fluids but substantially impermeable to other ingredients contained within
the
'30 dispensing device and the environment of use.
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I Water-attracting agents which are used to drive the osmotic flow of an
2 osmotic delivery device are referred to herein as "osmotic agents."
3 Figure 2 illustrates an example of an osmotic delivery device 10 according
to
4 an exemplary embodiment of the present invention. The osmotic delivery
device 10
generally includes a first chamber 20, a piston 30, and a second chamber or
6 reservoir 40, all of which may be enclosed within an elongated substantially
7 cylindrical capsule 15. The elongated capsule 15 is formed of a material
such as
8 titanium which is sufficiently rigid to withstand expansion of an osmotic
agent
s without changing size or shape. The elongated capsule 15 is impermeable to
fluids
and gases in the environment and to the ingredients contained therein.
11 The first chamber 20 contains an osmotic agent 25 which attracts water and
12 which may be in the form of a tablet. The osmotic agent 25 may be, for
example, a
13 non-volatile water soluble osmagent, an osmopolymer which swells upon
contact
14 with water, or a mixture of the two. The second chamber 40 contains a
beneficial
agent, such as a drug, to be delivered. The second chamber 40 is separated
from
16 the first chamber 20 by a movable piston 30. The movable piston 30 is a
17 substantially cylindrical member which is configured to fit within the
capsule 15 in a
18 sealed manner and to slide along a longitudinal axis within the capsule.
The piston
1s 30 preferably is formed of an impermeable resilient material which forms a
seal with
the walls of the capsule 15.
21 The drug delivery device 10 at its inlet end 12 includes a membrane 60
22 which forms at least a portion of a wall of the first chamber 20. The
membrane 60
23 is formed of a semipermeable material which allows fluid to pass from an
exterior
24 fluid environment into the first chamber 20 by osmosis to cause the osmotic
agent to
swell. The membrane 60 may be in the form of a semipermeable plug which is
26 inserted in an open end 12 of the capsule 15 as shown in Figure 2. The
membrane
27 60 is impermeable to the materials within the first chamber 20 so that they
do not 28 flow out of the capsule 15 through the membrane 60.
29 Materials from which the membrane 60 can be made are those that are 30
semipermeable and that can conform to the shape of the capsule 15 upon wetting
and
31 adhere to the rigid surface of the capsule 15. The membrane 60 expands as
it
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1 hydrates so that a seal is generated between the surface of the membrane 60
and the
2 capsule 15. The materials from which the membrane 60 is made vary based on
3 desired pumping rates and device configuration requirements and include, but
are
4 not limited to, plasticized cellulosic materials, enhanced
polymethylmethacrylates
such as hydroxyethylmethacrylate (HEMA) and elastomeric materials such as
6 polyurethanes and polyamides, polyether-polyamide copolymers, thermoplastic
7 copolyesters and the like.
8 In operation, when the delivery device 10 is situated in an aqueous
9 environment, water is drawn through the membrane 60 by osmosis into the
first
chamber 20 containing the osmotic agent. The osmotic agent swells, creating an
11 osmotic pressure in the first chamber 20 which is applied to the second
chamber 40
12 via the piston 30. The piston slides away from the membrane 60 forcing the
13 beneficial agent in the second chamber 40 to be delivered through at least
one orifice
14 50 in the second chamber. The osmotic pump provides a relatively constant
rate of
water intake which can be used to reliably deliver a desired quantity of the
beneficial
16 agent over time.
17 The orifice 50, according to one embodiment of the invention, is formed in
a
1s plug 52 of an elastic or semi-elastic material such as silicone, rubber.
santoprene;
*
19 polyurethane, or an elastomeric thermoplastic polymer such as C-FLEX. The
plug
52 is retained in an outlet end 14 of the capsule 15. The orifice 50 comprises
a slit
21 54 made through the elastic or semi-elastic plug 52 which may be fluidly
connected
22 to a flow moderator 56 disposed in the plug 52. The slit 54 and flow
moderator 56
23 fluidly connect the interior of the second chamber 40 to the external fluid
24 environment.
As shown in Figure 2, the plug 52 may have two sections. The first section
26 57 has an outer diameter which is small enough to allow the plug 52 to be
inserted
27 into the outlet end 14 of the capsule 15. The flow moderator 56 is disposed
in the
28 first section 57. The second section 53 contains at least a portion of the
slit 54 and
29 exteznds beyond the outlet end 14 of the capsule 15.
The orifice 50 operates as a valve which opens under the pressure of the
31 beneficial agent. The slit 54 of the orifice 50 may be under slight
compression, for
* Trade-mark
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1 example from compressive forces which form a seal between the outside of the
plug
2 52 and the inside of the reservoir 15, so that in the absence of flow, the
slit 54 forms
3 a closed valve which prevents fluid flow in either direction. Alternatively,
the
4 materials used and plug dimensions may be selected so that the slit seals or
closes
without the need for external compression. The slit 54 is preferably formed in
the
6 second section 53 of the plug 52 which extends beyond the capsule 15 so that
the
7 walls of the capsule 15 do not exert a significant closing force on the slit
54.
a In the presence of flow, the beneficial agent pushes through the slit 54,
9 opening up a channel for delivery of the beneficial agent. In the absence of
flow,
the slit 54 remains closed. When the slit is closed, back diffusion of
external fluids
11 is eliminated, which prevents contamination of the beneficial agent in the
second
12 chamber 40 by external fluids. In addition, forward diffusion of the
beneficial agent
13 out of the capsule 15 is prevented. In continuous flow osmotic delivery
systems, the
14 slit 54 will generally remain open throughout delivery of the beneficial
agent.
However, pulsatile and bolus type delivery systems will generally cause the
slit 54
16 to close during non-delivery periods.
17 When the osmotic pressure is high enough to open the slit 54 in the orifice
18 50, the slit 54 provides a flow channel of variable dimensions. The plug 52
in
19 which the slit 54 resides preferably. comprises an elastic or semi-elastic
material.
2o The osmotic pressure is great enough to overcome the elasticity of the plug
52 and
21 force open the slit 54. However, because the plug 52 is elastic, the flow
channel
22 which is formed is preferably just large enough to allow passage of the
beneficial
23 agent therethrough. The flow channel through the slit 54 may assume a range
of
24 sizes based on the osmotic pumping rate and the viscosity of the beneficial
agent, for
example.
26 The slit 54 generally opens to the smallest required diameter or opening to
27 allow for flow of beneficial agent through it. This is much smaller than
could be
28 achieved with a rigid channel due to machining and tolerance limitations
and/or
29 particulate clogging of such a small rigid channel.
As will be appreciated by those skilled in the art, the dimensions and
31 composition of the plug 52 and the slit 54 can be adjusted so that the slit
54 forms an
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1 orifice of a desired size when used with a particular beneficial agent and
osmotic
2 pump. For example, as the length of the slit 54 increases, the size of the
orifice
3 created by the slit 54 can increase. Also, as the thickness of the plug 52
along a.
4 longitudinal direction of the capsule 15 increases, the plug 52 becomes more
resistant to forming an orifice from the slit 54. The composition of the plug
52 also
s affects the tendency of the slit 54 to open into an orifice. A more elastic
material
7 will more easily form an orifice, or may form a wider orifice, than a more
rigid
8 material. By varying these properties of the plug 52 and slit 54, the
orifice can be
9 configured to open to a desired degree given the parameters of the delivery
device,
e.g., the viscosity of the beneficial agent, the flow rate of the osmotic
pump, and the
11 pressure of the osmotic pump. By varying the parameters listed above, one
can
12 achieve an orifice that "opens" at a predetermined internal pressure, e.g.
30 lbf/in2.
13 The ability to vary the size of the orifice 50 has the advantage that the
cross
14 sectional area of the orifice 50 can be made small under the operating
conditions of
the delivery device, which reduces diffusion of the beneficial agent out of
the
16 delivery device, as shown in Figure 1, and reduces back diffusion of
external fluids
17 into the delivery device. Generally, the system is designed so that the
slit 54 is
18 forced open to the smallest possible degree to let the formulation seep
through its
19 opening.
In addition, the requirement in prior delivery devices of a fixed dimension
21 orifice of sufficient size to permit passage of micro-aggregates is
eliminated because
22 the slit 54 allows a flow path to open around an obstruction in the orifice
50. In the
23 event that a suspended particle becomes lodged in the orifice 50, a new
flow path is
24 created around the obstacle, thereby preventing clogging. In operation, the
active
flow channel may be significantly smaller than is required in a fixed diameter
orifice
26 channel to prevent clogging.
27 Another advantage of the orifice 50 shown in Figure 2 is that the orifice
is
28 very compact and easily fits inside the delivery device 10, as compared
with a
29 conventional flow moderator which may be from 2 to 7 cm long, for example.
The
small size of the orifice 50 is advantageous when the delivery device 10 is
implanted
31 subcutaneously.
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t The flow moderator 56 may comprise a tube formed of a rigid or semi-rigid
2 material such as Teflon, HDPE, LDPE, or a metal, for example. The flow
3 moderator 56 forms a semi-rigid opening and allows compressive pressure to
be
4 used to form a seal between the outside of the plug 52 and the inside of the
reservoir
15 without compressing the slit 54 shut. Thus, as illustrated in Fig. 2, the
slit 54
6 may be located in the uncompressed second section 53 of the plug 52 such
that the
7 slit is not subject to the compression forces which form the seal between
the plug 52
8 and the capsule 15. Likewise, the slit 54 may extend into the first section
57 such
9 that the slit is subject to these compressive forces.
Hence, the flow moderator 56 functions to improve the seal between the plug
11 52 and the capsule 15. As shown in Figure 2, the plug 52 may have several
sealing
12 ridges 62 which each form a seal between the plug 52 and the capsule 15 to
13 effectively isolate the beneficial agent in the second chamber 40 from the
external
14 fluid environment. Because the flow moderator 56 may be formed of a rigid
material, it may exert an outward radial force on the plug 52, which is
preferably
16 less rigid than the flow moderator 56. This outward radial force increases
the
17 pressure exerted by the sealing ridges 62 against the inside of the capsule
15, which
18 improves the seal between the plug 52 and the capsule 15. In addition, the
outward
19 radial force increases the resistance of the plug 52 to being pushed out of
the capsule
15 by the osmotic pressure generated by the osmotic pump. In other embodiments
21 of the present invention, the outward radial forces may also regulate the
flow of the
22 beneficial agent and prevent back diffusion of external fluids into the
capsule 15.
23 According to one exemplary embodiment of the present invention, the slit 54
24 illustrated in Figure 2 is formed by inserting a hypodermic needle, pin, or
blade
through the first and second sections 57, 53 of the plug 52. For example, a
26 hypodermic needle have a predetermined diameter is inserted through the
body of
27 the orifice 20 along the center axis of the orifice (parallel with the
longitudinal axis
28 of the capsule 15). Thereafter, the needle is removed from the orifice 50.
After the
29 slit 54 has been formed in the orifice 50, the flow moderator 56 is
inserted into the
ao first section 57 of the plug 52. Depending upon the material of the plug
52, and the
31 dimensions of the slit 54 and flow moderator 56, it may be necessary to
drill, carve,
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1 punch, or mold a cylindrical recess in the first section 57 to receive the
flow
2 moderator. In any case, the flow moderator 56 is preferably positioned
within the
3 first section 57, and secured to the first section 57 via an interference
fit, although
4 adhesives, threads and other means may be used to secure the flow moderator
to the
first section of the plug 52. An end of the flow moderator 56 may protrude
from the
6 first section 57, may be located within the first section, or may be
inserted in the
7 first section such that it is flush with the first section.
8 The slit 54 may also be fonned after the flow moderator 56 has. been
inserted
s into the first section 57 of the plug 52. According to this method, the flow
io moderator 56 is first inserted into the first section 57 of the plug 52.
Thereafter, a
11 needle or device for forming the slit 54 is inserted completely through the
12 cylindrical channel of the tubular flow moderator 56 and through the second
section
13 53 of the plug 52 to form the slit.
14 For example, an orifice 50, such as that illustrated in Figure 2, may be
formed by first inserting a 1.5 mm long portion of a 21 gauge (diameter of
16 approximately 0.8 mm) hypodermic needle into the first section 57 of a plug
52 of
17 styrene ethylene butadiene styrene block copolymer (C-FLEX LS 55A,
18 commercially available from CONSOLIDATED POLYMER TECHNOLGIES).
19 The 1.5 mm long portion of the 21 gauge hypodermic needle is preferably at
least
2o half the length of the final slit 54 to be formed. The following dimensions
of the
21 plug 52 and capsule 15 are also preferred for this example: (1) the C-FLEX
plug 52
22 is approximately 3.85 mm long (measured on an axis parallel with the
longitudinal
23 axis of the capsule into which the orifice 50 is to be inserted), although
only 3.13
24 mm of the plug is inserted into the capsule 15 after the orifice 50 has
been
fabricated; (2) the plug 52 includes four equally spaced sealing ridges 62,
each
26 having an outer diameter of approximately 3.24 mm and each approximately
0.26
27 mm thick (measured on an axis parallel with the longitudinal axis of the
capsule into
28 which the orifice 50 is to be inserted); (3) the diameter of the
cylindrical body of the
29 plug 52 at the base of the sealing ridges 62 is approximately 2.98 mm; and
(4) the
inner diameter of the capsule 15 that receives the plug 52 is approximately
3.00 mm.
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1 After the 1.5 mm long portion of the 21 gauge hypodermic needle has been
2 inserted into the first section 57 of the plug 52, a second hypodermic
needle having
3 a smaller diameter than the portion of the 21 gauge hypodermic needle is
inserted
4 into the portion of the 21 gauge hypodermic needle and completely through
the first
and second sections 57, 53 of the plug 52. This step forms the slit 54, and
also
6 removes any plug material inside the portion of the 21 gauge hypodermic
needle to
7 form the flow moderator 56. If the second hypodermic needle is sized to
tightly fit
a through the 21 gauge flow moderator 56, the resulting slit 54 will be
approximately
9 0.4 mm wide as measured perpendicular to the center axis of the orifice 50.
An
1o orifice 50 having the above dimensions is intended to be particularly
useful for
11 delivering high viscosity formulations of beneficial agents, such as 3%
sodium
12 carboxymethyl cellulose in water.
13 Figure 9 is a graph of the release rate of beneficial agent over time and
14 compares two osmotic delivery systems having a spiral flow moderator with
two
osmotic delivery systems or devices 10 having an orifice 50 according to
16 embodiments of the present invention, such as that illustrated in Figure 2.
The
17 osmotic delivery devices 10 tested in Figure 9 included the capsule 15 and
orifice 50
18 dimensioned and described above having the C-FLEX LS 55A plug 52 with the
0.4
19 mm slit 54 and the 21 gauge flow moderator 56.
As illustrated in Figure 9, the two osmotic delivery systems having a spiral
21 flow moderator and the two osmotic delivery systems 10 having the orifice
50
22 according to embodiments of the present invention were tested. The
respective
23 systems were configured to deliver a beneficial agent, in this case water
with blue
24 dye, over a one month and one year time period.
The osmotic delivery system 10 according to the present invention that was
26 configured to deliver the beneficial agent over a one year time period
delivered
27 approximately 0.4 uL/day of the beneficial agent. Comparatively, the
osmotic
28 delivery system incorporating the spiral flow modulator and configured to
deliver
29 the beneficial agent over a one year time period also delivered
approximately 0.4
uL/day of the beneficial agent. Thus, Figure 9 illustrates that the osmotic
delivery
31 system 10 incorporating the orifice 50 and configured to deliver the
beneficial agent
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1 over a one year time period performed as well as the osmotic delivery system
2 incorporating the spiral flow modulator.
3 The osmotic delivery system 10 according to the present invention that: was
4 configured to deliver the beneficial agent over a one month time period
delivered
roughly 1.3 uL/day of the beneficial agent. Comparatively, the osmotic
delivery
6 system incorporating the spiral flow modulator and configured to deliver the
7 beneficial agent over a one month time period also delivered roughly 1.3
uL/day of
8 the beneficial agent. Thus, Figure 9 illustrates that the osmotic delivery
system 10
9 incorporating the orifice 50 and configured to deliver the beneficial agent
over a one
io month time period performed as well as the osmotic delivery system
incorporating
11 the spiral flow modulator. In sum, the results depicted in Figure 9
illustrate that the
12 tested orifices 50 were as effective as the spiral flow moderators in
delivering a
13 beneficial agent at different release rates.
14 Figure 3 illustrates another embodiment of the invention in which a
catheter
156 is provided in fluid communication between the slit 154 and the capsule
115.
16 As shown in Figure 3, the delivery device 110 includes a membrane 160 which
may
17 be in the form of a diffusion plug, a first chamber 120 which contains an
osmotic
18 agent 125, a second chamber 140 which contains a beneficial agent, and a
moveable
ig piston 130 which separates the first chamber 120 from the second chamber
140.
2o The osmotic pump, including the first and second chambers, piston, and
membrane,
21 functions in the same manner as the pump of Figure 2.
22 As shown in Figure 3, the delivery device 110 includes a plug 142 having a
23 catheter 156 fixed therein. The plug 142 fits in the outlet end 114 of the
capsule
24 115 and may include a plurality of ridges 162 to seal the plug 142 to the
capsule
115. The plug 142 may have a first portion 147 which fits inside the walls of
the
26 capsule 115 and a second portion 143 which extends beyond the outlet end
114 of
27 the capsule 115. The plug 142 may be formed of an elastic or semi-elastic
material
28 such as silicone, rubber, santoprene, polyurethane, etc.
29 The catheter 156 is disposed in the plug 142 and is in fluid communication
with the beneficial agent in the second chamber 140. The catheter 156 is
preferably
31 formed of a rigid or semi-rigid material such as Teflon, HDPE, LDPE, or a
metal
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1 so that it exerts a radially outward force on the plug 142 to increase the
pressure of
2 the ridges 162 on the inside wall of the capsule 115. The increased pressure
s improves the seal between the plug 142 and the capsule 115 and increases the
4 resistance of the plug 142 to being forced out of the capsule 115 by the
osmotic
pressure generated by the osmotic pump.
6 The catheter 156 is also in fluid communication with a slit 154 formed in a
7 flexible member 152. The flexible member 152 preferably comprises an elastic
or
8 semi-elastic material such as silicone, rubber, santoprene, polyurethane,
etc. The
9 flexible member 152 may have two sections, a first section 157 in which the
end of
1o the catheter 156 is disposed, and a second section 153 in which the slit
154 is
11 located. The slit 154 functions in much the same manner as the slit 54 of
Figure 2.
12 However, the slit 154 is not subject to compressive forces created by the
seal
= 13 between the plug 142 and the capsule 115.
14 The slit 154 is designed such that in the absence of flow, the slit 154
forms a
closed valve which prevents fluid flow in either direction. In the presence of
flow,
16 the beneficial agent pushes through the slit 154, opening up a channel for
delivery of
17 the beneficial agent. The dimensions and composition of the flexible member
152
18 and slit 154 can be chosen so that the slit 154 forms an orifice of a
desired size
19 under the operating parameters of the delivery device, e.g., the viscosity
of the
2o beneficial agent, the flow rate of the osmotic pump, and the pressure of
the osmotic
21 pump.
22 Because the flexible member 152 is elastic, the flow channel which is
formed
23 is preferably just large enough to allow passage of the beneficial agent
therethrough.
24 The variability of the size of the orifice has the advantage that the cross
sectional
area of the orifice is small (e.g., significantly.smaller than a flow
moderator of f"ixed
26 diameter), which reduces diffusion of the beneficial agent out of the
delivery device,
27 as shown in Figure 1, and reduces diffusion of external fluids into the
delivery
28 device. The slit 154 also allows a flow path to open around an obstruction
in the slit
29 154.
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1 The catheter 156 may have dimensions such that it performs as a flow
2 moderator, if desired, to further reduce diffusion of the beneficial agent
out the. slit
3 154 and back diffusion of external fluids into the second chamber 140.
4 The catheter 156 is also useful when the desired point of delivery of the
beneficial agent is difficult to access. For example, it may be advantageous
6 therapeutically to deliver the beneficial agent at a location which cannot
7 accommodate or tolerate the capsule 115. In this situation, the capsule 115
may be
8 implanted in a more acceptable location while the catheter 156 transports
the
9 beneficial agent to the slit 154 at the delivery site. This embodiment may
also be
1 o utilized to make the capsule 115 more accessible to a treating physician
rather than
11 being implanted at a location which requires an invasive procedure. For
example,
12 the capsule 115 may be implanted close to the surface of the skin while the
catheter
13 156 delivers the beneficial agent to a more remote location.
14 The improved performance of the exemplary delivery devices of Figures 2 and
.3 is
shown in Figure 4. Figure 4 is a graph of the release rate in microliters per
day
16 over time of the delivery devices of Figures 2 and 3. Figure 4 also shows
the
17 release rate of a delivery device having a tubular flow moderator orifice
in the shape
18 of a spiral. The data used in Figure 4 were obtained by placing each
delivery device
19 in a release rate bath. The delivery devices were filled with a 1% solution
of blue
2o dye in deionized water. At fixed points in time, the concentration of blue
dye in the
21 release rate bath was measured. The experiment was conducted five times,
and the
22 error bars shown in Figure 4 represent the standard deviation of the
measurements.
23
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1 The procedure and materials used in obtaining the data shown in Figure 4 are
2 as follows:
3
4 Granulation Tablet Compression:
TOWLING: 0.117" flat face
6 GRANULATION: 80.0% NaCI, 5.0% NaCMC 7H4F, 14.25%
7 Povidone, 0.75 % Magnesium Stearate.
8 TABLET WEIGHT: 0.0841 g.
9 TABLET HEIGHT: 0.247 in.
1o COMPRESSION: 5001b.
11
Tablet No. Tablet Weight (g) Tablet Height
(in)
1 0.0955 0.309
2 0.0877 0.284
3 0.0848 0.273
4 0.0914 0.294
5 0.0825 0.265
Average 0.0884 0.385
12
13 PROCEDURE:
14 1. Lubricate large flanched piston with medical fluid 100cs CODE 80036
CONTROL 258887
16 2. Prime capsule (membrane end).
17 3. Insert large flanched piston into Hoechst Celanese capsule using the
piston
18 inserted.
1s 4. Push piston up & down using a rod.
5. Insert osmotic engine tablet into capsule from the membrane end and push
21 engine tablet down.
22 6. Insert half way the membrane plug.
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2 7. Add two drops of glue in each side of membrane plug.
3 8. Press all the way down membrane plug and wipe glue residue with a paper
4 towel.
9. Add beneficial agent into capsule almost all the way to the top.
6 10. Insert orifice.
7 11. Insert orifice half way and add two drops of glue in each side of
orifice plug
a (all orifices were glued except systems 26-30).
9
lo COMPONENTS:
11 Formulation #1: 1 % blue dye in deionized water
12 Membrane: Fast "K" 100% hytrel 8171
13 Engine Tablet: 80.0% NaCI, 5.0% NaCMC 7H4F, 14.25% Povidone, 0.75.%
14 Magnesium Stearate.
Piston: Large santoprene flanched
16 Orifice: 1-5 screw spiral
17 Orifice: 11-15 external flow moderator (Figure 3)
18 Orifice: 21-25 internal 1 nun duckbill (Figure 2)
19
As shown in Figure 4, the release rate of the delivery devices of Figures 2
21 and 3 having the slit orifices is significantly more constant than the
release rate of
22 the delivery device having a spiral shaped flow moderator. This
characteristic is of
23 course very important when the delivery device is used to supply drugs to
humans
24 over an extended period of time. The slit orifice may be used to alter the
start-up
beneficial agent delivery profile by changing the pressure at which the
orifice opens
26 and/or decreasing the initial diffusive burst from the flow modulator.
27 In assembling the delivery device of the present invention, the beneficial
28 agent may also be added with the capsule after the orifice has been
inserted into the
29 capsule. In such an assembly, a needle is inserted through the orifice and
into the
capsule such that beneficial agent is delivered into the capsule via the
needle. This
31 technique is advantageous because the slit orifice allows air to escape the
capsule as
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1 the beneficial agent fills the capsule. Thus, after the delivery device is
inserted into
2 the environment of use, the osmotic agent need not compress any air bubbles
in the
3 beneficial agent which would ordinarily delay start-up of beneficial agent
delivery.
4 Figure 5 illustrates another embodiment of the invention which includes a
mechanism for varying the pressure required to open the orifice. As shown in
6 Figure 5, the orifice 250 is located at the outlet end 214 of a capsule 215.
The
7 delivery device 210 also includes a membrane 260, a first chamber 220
containing
8 an osmotic agent, a second chamber 240 containing a beneficial agent, and a
s moveable piston 230 separating the first chamber 220 from the second chamber
240.
The membrane 260, osmotic agent, piston 230, and second chamber 240 form an
11 osmotic pump which functions as described above with respect to Figures 2
and 3.
12 The orifice 250, according to an exemplary embodiment, comprises three
13 sections. A first portion 257 is located between the slit 254 and the
second chamber
14 240 and is in fluid communication with both. A second portion 253 contains
the slit
254. A third portion 259 occupies the annular space between the first and
second
16 portions and the inner wall of the capsule 215.
17 The slit 254 is housed in the second portion 253. The second portion is
18 generally cylindrical in shape and preferably is formed of an elastic or
semi-elastic
19 material such as silicone, rubber, santoprene, polyurethane, etc. The
elasticity of
the second portion 253 allows the slit 254 to open under pressure from the
beneficial
21 agent.
22 Upstream of the slit 254 and second portion 253 is the first portion 257.
The
23 first portion 257 is also generally cylindrical in shape and has an inner
recess 252.
24 The outer radius of the first portion 257 may be greater than the outer
radius of the
second portion 253 so that a shoulder 251 is formed to secure the first and
second
26 portions in the delivery device 210. The first and second portions may be
integrally
27 formed as a single piece of material.
28 According to a preferred embodiment, the inner recess 252 of the first
29 portion 257 has at least one wall 258 which is at an acute angle to the
direction of
flow 255 of the beneficial agent. Preferably, the inner recess 252 is in the
shape of
31 a cone so that its entire wa11258 is at an acute angle with respect to the
direction of
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1 flow 255 of the beneficial agent. As the beneficial agent is forced into the
inner
2 recess 252, the beneficial agent exerts a force on the wall 258 of the inner
recess
3 252 which has a radial component. The radial force operates to open the slit
254 in
4 the second portion 253 of the orifice. Because the first and second portions
are
formed of an elastic or semi-elastic material, the force of the beneficial
agent opens
6 the slit 254 just wide enough to deliver the beneficial agent with very
little if any
7 forward diffusion of the beneficial agent or backward diffusion of external
fluids
a into the second chamber 240.
9 The shape and composition of the first and second portions 257 and 253 and
of the slit 254 may be adapted to accommodate beneficial agents of different
11 viscosities or to adjust the pressure required to open the slit 254. For
example, a
12 beneficial agent with a relatively low viscosity will more easily flow
through a
13 smaller opening of the slit 254 than a beneficial agent with a, higher
viscosity. To
14 equalize this discrepancy, the angle between the wall 258 and the direction
of flow
255 can be adjusted for the viscous beneficial agent so that the slit is more
easily
16 opened. The angle between the wall 258 and the direction of flow 255 can
also be
17 adjusted to vary the pressure at which the slit will open and close for a
beneficial
18 agent of a given viscosity. In addition the dimensions and composition of
the second
1s portion 253 can be adjusted so that the slit 254 forms an orifice of a
desired size
under the operating parameters of the delivery device, e.g., the viscosity of
the
21 beneficial agent, the flow rate of the osmotic pump, and the pressure of
the osmotic
22 pump.
23 The third portion 259 occupies the annular space between the first and
24 second portions and the inner wall of the capsule 215. The third portion
259 may
have grooves 272 which mate with corresponding ridges 274 projecting from the
26 inner wall of the capsule 215. The grooves 272 and ridges 274 may be
circular or
27 they may be in the form of screw threads such that the third portion 259
may be
28 screwed into the outlet end of the capsule 215. The ridges and grooves are
provided
29 to secure the third portion 259 in the end of the capsule 215 in spite of
the osmotic
pressure generated by the osmotic pump.
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1 The third portion 259 also includes an inwardly extending flange 276 which
2 contacts the shoulder 251 formed between the first and second portions 257
and 253.
3 The flange 276 contacts the shoulder 251 to retain the first and second
portions in
4 the capsule 215. The flange 276 may also function to apply a slight radial
inward
pressure on the second portion 253 so that the slit 254 remains closed in the
absence
6 of flow.
7 The orifice 250 provides the advantage that the flow channel may be
a significantly smaller than is required in a fixed diameter orifice, since
the flow
9 channel opens just large enough to deliver the beneficial agent. In
addition, in the
event that a suspended particle becomes lodged in the orifice 250, a new flow
path is
11 created around the obstacle. The orifice 250 is also very compact, as
illustrated in
12 Figure 5.
13 The improved performance of the exemplary delivery device of Figure 5 is
14 shown in Figure 6. Figure 6 is a graph of the release rate in microliters
per day
over time of the delivery device of Figure 5. Figure 6 also shows the release
rate of
16 a delivery device having a flow moderator orifice in the shape of a spiral.
The data
17 used in Figure 6 were obtained by placing each delivery device in a release
rate
18 bath. The delivery devices were filled with a 1% solution of blue dye in
deionized
1 s water. At fixed points in time, measurements were taken of the
concentration of
2o blue dye in the release rate bath.
21 As shown in Figure 6, the release rate of the delivery devices of Figure 5
22 having the slit orifice is significantly more constant than the release
rate of the
23 delivery device having a spiral shaped flow moderator.
24 Figure 7 illustrates another embodiment of an orifice which includes an
inner
recess 352 and an inner cylindrical member 359. As shown in Figure 7, the
orifice
26 350 is located at the outlet end 314 of the capsule 315. The delivery
device 310 also
27 includes a membrane 360, a first chamber 320 containing an osmotic agent, a
second
28 chamber 340 containing a beneficial agent, and a moveable piston 330
separating the
29 first chamber 320 from the second chamber 340. The membrane 360, osmotic
agent, piston 330, and second chamber 340 form an osmotic pump which functions
31 as described above with respect to Figures 2 and 3.
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1 The orifice 350, according to an exemplary embodiment, comprises three
2 components. A first portion 357 is located between the slit 354 and the
second
3 chamber 340 and is in fluid communication with both. A second portion 353
4 contains the slit 354. A third portion 359 resides in the annular space
between the
first and second portions and the inner wall of the capsule 315.
6 The slit 354 is housed in the second portion 353. The second portion is
7 generally cylindrical in shape and preferably is formed of an elastic or
semi-elastic
8 material such as silicone, rubber, santoprene, polyurethane or an
elastomeric
9 thermoplastic polymer such as C-FLEX. The elasticity of the second portion
353
allows the slit 354 to open under pressure from the beneficial agent.
11 Upstream of the slit 354 and second portion 353 is the first portion 357.
The
12 first portion 357 is also generally cylindrical in shape and has an inner
recess 352.
13 The outer radius of the first portion 357 may be greater than the outer
radius of the
14 second portion 353 so that a shoulder 351 is formed to secure the first and
second
portions in the delivery device 310. The first and second portions may be
integrally
16 formed as a single piece of material.
17 According to a preferred embodiment, the inner recess 352 of the first
18 portion 357 has at least one wall 358 which is at an acute angle to the
direction of
19 flow 355 of the beneficial agent. Preferably, the inner recess 352 is in
the shape of
2o a cone so that its entire wall 358 is at an acute angle with respect to the
direction of
21 flow 355 of the beneficial agent. As the beneficial agent is forced into
the inner
22 recess 352, the beneficial agent exerts a force on the wall 358 of the
inner recess
23 352 which has a radial component. The radial force operates to open the
slit 354 in
24 the second portion 353 of the orifice. Because the first and second
portions are
formed of an elastic or semi-elastic material, the force of the beneficial
agent opens
26 the slit 354 just wide enough to deliver the beneficial agent with little
if any forward
27 diffusion of the beneficial agent or backward diffusion of external fluids
into the
28 second chamber 340. The shape of the inner recess 352 (e.g., the angle of
the wall
29 358) may be adapted to accommodate beneficial agents of different
viscosities or to
3o adjust the pressure required to open the slit 354. In addition, the
dimensions and
31 composition of the second portion 353 can be chosen so that the slit 354
forms an
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1 orifice of a desired size under the operating parameters of the delivery
device, e.g.,
2 the viscosity of the beneficial agent, the flow rate of the osmotic pump,
and the
3 pressure of the osmotic pump.
4 The third portion 359 resides in the annular space between the first and
second portions and the inner wall of the capsule 315. The third portion 359
is
6 preferably formed of a rigid material such as titanium. The third portion
may be
7 generally in the form of an inner cylindrical member or "cup" with a hole
380 in its
8 bottom. The third portion 359 is preferably formed to have an outer diameter
which
9 is small enough that the third portion 359 may be pressed into the outlet
end 314 of
the capsule 315. The outer diameter of the third portion 359 is preferably
large
11 enough, however, that the third portion 359 is frictionally retained in the
outlet end
12 314 of the capsule 315 in the presence of the osmotic pressure generated by
the
13 osmotic pump. When properly dimensioned, the frictional force between the
third
14 portion 359 and the capsule 315 is sufficient to permanently retain the
third portion
359 in the capsule 315.
16 The third portion 359 also includes an inwardly extending flange 376 which
17 contacts the shoulder 351 formed between the first and second portions 357
and 353.
18 The flange 376 contacts the shoulder 351 to retain the first and second
portions in
19 the capsule 315. The flange 376 preferably does not extend all the way
inward to
the second portion 353 so that a gap 390 exists between the second portion
21 containing the slit 354 and the flange 376. The gap 390 is provided so that
the
22 flange 376 does not exert any pressure on the slit 354.
23 The orifice 350 provides the advantages that the flow channel which opens
24 under pressure from the beneficial agent may be significantly smaller than
is
required in a fixed diameter orifice, since the flow channel opens just large
enough
26 to deliver the beneficial agent. In addition, in the event that a suspended
particle
27 becomes lodged in the orifice 350, a new flow path is created around the
obstacle.
28 The rigid third portion 359 is also very effective in maintaining the
orifice 350 in
29 the capsule against the osmotic pressure. The orifice is also very compact,
which is
advantageous for subcutaneous implantation.
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1 Figure 8 illustrates another embodiment of an orifice 450 which includes a
2 plurality of slit orifices 454. As shown in Figure 8, the orifice 450 is
located at the
3 outlet end of the capsule 415. The delivery device 400 also includes a
membrane
4 460, a first chamber 420 containing an osmotic agent, a second chamber 440
containing a beneficial agent, and a movable piston 430 separating the first
chamber
6 420 from the second chamber 440. The membrane 460, osmotic agent, piston
430,
7 and second chamber 440 form an osmotic pump which functions as described
above
8 with respect to Figures 2 and 3.
9 The orifice 450, according to an exemplary embodiment, includes a plurality
of slit orifices similar to those described above in reference to Figures 2,
5, and 7.
11 As shown in Figure 8, an inner cylindrical member 459 is positioned in the
end of
12 the capsule 415 opposite the membrane 460. In this embodiment, a flexible
member
13 456, which contains the plurality of slit orifices 454 and inner recesses
452, has
14 been prepositioned in the inner cylindrical member 459. Similar to the
embodiment
depicted in Figure 5, the inner cylindrical member 459 may be made of a
material
16 which helps maintain the seal between the capsule 415 and the orifice 450.
For
17 example, the inner cylindrical member 459 may be made of less resilient
material
18 than the flexible member 456 which contains the plurality of slits 454. In
another
19 embodiment of the present invention not depicted, the inner cylindrical
member 459
is not included, and the flexible member 456 is adapted and configured to form
a
21 seal with the capsule 415.
22 As illustrated in Figure 8, the orifice 450 includes a plurality of slit
orifices
23 454 and inner recesses 452, which are particularly useful for delivering
beneficial
24 agents having suspensions of bioactive macromolecules such as proteins and
genes.
Known delivery orifices may cause such suspension formation to separate as the
26 formulation is moved into a small chamber such as a helical orifice prior
to being
27 released into the environment of use. The embodiment of the present
invention
28 which incorporates a plurality of slit orifices 454 allows such suspension
29 formulations to travel relatively unrestricted, minimizing the amount of
separation
3o before it exits the delivery device 400. In this regard, the plurality of
slit orifices
31 454 in combination with the plurality of inner recesses 452 allows for a
nearly
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1 constant front of beneficial agent, such as suspensions containing bioactive
2 macromolecules, to be released from the delivery device 400, while also
minimizing
3 back diffusion of external fluids into the d'elivery device. Furthermore,
the
4 embodiment of the present invention illustrated in Figure 8 also provides
the many
advantages described above in reference to Figures 1- 7.
6 In the event that one or some of the slit orifices 454 becomes clogged with
7 macromolecules or particles, the other non-clogged slit orifices of the
delivery
8 device 400 will continue to release the beneficial agent. Thus, the
plurality of slits
s 454 and recesses 452 acts as a safety, ensuring that beneficial agent
delivery
continues.
11 Materials which may be used for the capsule should be sufficiently strong
to
12 ensure that the capsule will not leak, crack, break, or distort under
stresses to which
13 they would be subjected during implantation or under stresses due to the
pressures
14 generated during operation. The capsule may be formed of chemically
inert.and
biocompatible, natural or synthetic materials which are known in the art. The
16 material of the capsule is preferably a non-bioerodible material which
remains in the
17 patient after use, such as titanium. However, the material of the capsule
may
1s alternatively be of bioerodible material which bioerodes in the environment
after
19 dispensing of the beneficial agent. Generally, preferred materials for the
capsule are
those acceptable for human implants.
21 In general, typical materials of construction suitable for the capsule
22 according to the present invention include non-reactive polymers or
biocompatible
23 metals or alloys. The polymers include acrylonitrile polymers such as
acrylonitrile-
24 butadiene-styrene terpolymer, and the like; halogenated polymers such as
polytetrafluoroethylene, polychlorotrifluoroethylene, copolymer of
26 tetrafluoroethylene and hexafluoropropylene; polyimide; polysulfone;
27 polycarbonate; polyethylene; polypropylene; polyvinylchloride-acrylic
copolymer;
28 polycarbonate-acrylonitrile-butadiene-styrene; polystyrene; and the like.
Metallic
29 materials useful for the capsule include stainless steel, titanium,
platinum, tantalum,
gold, and their alloys, as well as gold-plated ferrous alloys, platinum-plated
ferrous
31 alloys, cobalt-chromium alloys and titanium nitride coated stainless steel.
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1 In general, materials suitable for use in the piston are elastomeric
materials
2 including the non-reactive polymers listed above, as well as elastomers in
general,
3 such as polyurethanes and polyamides, chlorinated rubbers, styrene-butadiene
4 rubbers, and chloroprene rubbers.
The osmotic tablet is an osmotic agent which is a fluid-attracting agent used
6 to drive the flow of the beneficial agent. The osmotic agent may be an
osmagent, an
7 osmopolymer, or a mixture of the two. Species which fall within the category
of
8 osmagent, i.e., the non-volatile species which are soluble in water and
create the
9 osmotic gradient driving the osmotic inflow of water, vary widely. Examples
are
well known in the art and include magnesium sulfate, magnesium chloride,
11 potassium sulfate, sodium chloride, sodium sulfate, lithium sulfate, sodium
12 phosphate, potassium phosphate, d-mannitol, sorbitol, inositol, urea,
magnesium
13 succinate, tartaric acid, raffinose, and various monosaccharides,
oligosaccharides
14 and polysaccharides such as sucrose, glucose, lactose, fructose, and
dextran, as well
as mixtures of any of these various species.
1s Species which fall within the category of osmopolymer are hydrophilic
17 polymers that swell upon contact with water, and these vary widely as well.
18 Osmopolymers may be of plant or animal origin, or synthetic, and examples
of
19 osmopolymers are well known in the art. Examples include: poly(hydroxy-
alkyl
methacrylates) with molecular weight of 30,000 to 5,000,000,
21 poly(vinylpyrrolidone) with molecular weight of 10,000 to 360,000, anionic
and
22 cationic hydrogels, polyelectrolyte complexes, poly(vinyl alcohol) having
low
23 acetate residual, optionally cross-linked with glyoxal, formaldehyde or
24 glutaraldehyde and having a degree of polymerization of 200 to 30,000, a
mixture of
methyl cellulose, cross-linked agar and carboxymethylcellulose, a mixture of
26 hydroxypropyl methylcellulose and sodium carboxymethylcellulose, polymers
of N-
27 vinyllactams, polyoxyethylene-polyoxypropylene gels, polyoxybutylene-
28 polyethylene block copolymer gels, carob gum, polyacrylic gels, polyester
gels,
29 polyurea gels, polyether gels, polyamide gels, polypeptide gels, polyamino
acid
gels, polycellulosic gels, carbopol acidic carboxy polymers having molecular
31 weights of 250,000 to 4,000,000, Cyanamer polyacrylamides, cross-linked
indene-
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1 maleic anhydride polymers, Good-Rite polyacrylic acids having molecular
weights
2 of 80,000 to 200,000, Polyox polyethylene oxide polymers having molecular
3 weights of 100,000 to 5,000,000, starch graft copolymers, and Aqua-Keeps
acrylate
4 polymer polysaccharides.
Delivery capsules in accordance with the present invention for the delivery of
s beneficial agents, may be manufactured by a variety of techniques, many of
which
7 are known in the art.
8 In one such embodiment of this invention, the beneficial agents contained in
s' the second chamber are flowable compositions such as liquids, suspension,
or
io slurries, and are poured into the capsule after the osmotic agent and the
piston have
11 been inserted. Alternatively, such flowable compositions may be injected
with a
12 needle through a slit in the plug, which allows for filling without air
bubbles. Still
13 further alternatives may include any of the wide variety of techniques
known in the
14 art for forming capsules used in the pharmaceutical industry.
Animals to whom drugs may be administered using systems of this invention
16 include humans and other animals. The invention is of particular interest
for
17 application to humans and household, sport, and farm animals, particularly
18 mammals. For the administration of beneficial agents to animals, the
devices of the
1 s present invention may be implanted subcutaneously or intraperitoneally or
at any
other location in a biological environment where aqueous body fluids are
available
21 to activate the osmotic engine.
22 The devices of this invention are also useful in environments outside of
23 physiological or aqueous environments. For example, the devices may be used
in
24 intravenous systems (attached to an IV pump or bag or to an IV bottle, for
example)
for delivering beneficial agents to animals, primarily to humans. They may
also be
26 utilized in blood oxygenators, kidney dialysis and electrophoresis, for
example.
27 Additionally, devices of the present invention may be used in the
biotechnology
28 area, such as to deliver nutrients or growth regulating compounds to cell
cultures.
29 The present invention applies to the administration of beneficial agents in
general, which include any physiologically or pharmacologically active
substance.
31 The beneficial agent may be any of the agents which are known to be
delivered to
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1 the body of a human or an animal such as drug agents, medicaments, vitamins,
2 nutrients, or the like. The beneficial agent may also be an agent which is
delivered
3 to other types of aqueous environments such as pools, tanks, reservoirs, and
the
4 like. Included among the types of agents which meet this description are
biocides,
sterilization agents, nutrients, vitamins, food supplements, sex sterilants,
fertility
6 inhibitors and fertility promoters.
7 Drug agents which may be delivered by the present invention include drugs
8 which act on the peripheral nerves, adrenergic receptors, cholinergic
receptors, the
9 skeletal muscles, the cardiovascular system, smooth muscles, the blood
circulatory
system, synoptic sites, neuroeffector junctional sites, endocrine and hormone
11 systems, the immunological system, the reproductive system, the skeletal
system,
12 autacoid systems, the alimentary and excretory systems, the histamine
system and
13 the central nervous system. Suitable agents may be selected from, for
example,
14 proteins, enzymes, hormones, polynucleotides, nucleoproteins,
polysaccharides,
glycoproteins, lipoproteins, polypeptides, steroids, analgesics, local
anesthetics,
16 antibiotic agents, anti-inflammatory corticosteroids, ocular drugs and
synthetic
17 analogs of these species.
18 Examples of drugs which may be delivered by devices according to this
19 invention include, but are not limited to prochlorperzine edisylate,
ferrous sulfate,
2o aminocaproic acid, mecamylamine hydrochloride, procainamide hydrochloride,
21 amphetamine sulfate, methamphetamine hydrochloride, benzamphetamine
22 hydrochloride, isoproterenol sulfate, phenmetrazine hydrochloride,
bethanechol
23 chloride, methacholine chloride, pilocarpine hydrochloride, atropine
sulfate,
24 scopolamine bromide, isopropamide iodide, tridihexethyl chloride,
phenformin
hydrochloride, methylphenidate hydrochloride, theophylline cholinate,
cephalexin
26 hydrochloride, diphenidol, meclizine hydrochloride, prochlorperazine
maleate,
27 phenoxybenzamine, thiethylperzine maleate, anisindone, diphenadione
erythrityl
28 tetranitrate, digoxin, isoflurophate, acetazolamide, methazolamide,
29 bendroflumethiazide, chloropromaide, tolazamide, chlormadinone acetate,
phenaglycodol, allopurinol, aluminum aspirin, methotrexate, acetyl
sulfisoxazole,
31 erythromycin, hydrocortisone, hydrocorticosterone acetate, cortisone
acetate,
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1 dexamethasone and its derivatives such as betamethasone, triamcinolone,
2 methyltestosterone, 17-S-estradiol, ethinyl estradiol, ethinyl estradiol 3-
methyl
3 ether, prednisolone, 17a-hydroxyprogesterone acetate, 19-nor-progesterone,
4 norgestrel, norethindrone, norethisterone, norethiederone, progesterone,
norgesterone, norethynodrel, aspirin, indomethacin, naproxen, fenoprofen,
sulindac,
6 indoprofen, nitroglycerin, isosorbide dinitrate, propranolol, timolol,
atenolol,
7 alprenolol, cimetidine, clonidine, imipramine, levodopa, chlorpromazine,
8 methyldopa, dihydroxyphenylalanine, theophylline, calcium gluconate,
ketoprofen,
s ibuprofen, cephalexin, erythromycin, haloperidol, zomepirac, ferrous
lactate,
1o vincamine, diazepam, phenoxybenzamine, diltiazem, mihinone, capropril,
mandol,
11 quanbenz, hydrochlorothiazide, ranitidine, flurbiprofen, fenufen,
fluprofen,
12 tolmetin, alclofenac, mefenamic, flufenamic, difuinal, nimodipine,
nitrendipine,
13 nisoldipine, nicardipine, felodipine, lidoflazine, tiapamil, gallopamil,
amlodipine,
14 mioflazine, lisinoipril, enalapril, enalaprilat, captopril, ramipril,
famotidine,
nizatidine, sucralfate, etintidine, tetratolol, minoxidil, chlordiazepoxide,
diazepam,
16 amitriptyline, and imipramine. Further examples are proteins and peptides
which
17 include, but are not limited to, insulin, colchicine, glucagon, thyroid
stimulating
18 hormone, parathyroid and pituitary hormones, calcitonin, renin, prolactin,
1s corticotrophin, thyrotropic hormone, follicle stimulating hormone,
chorionic
gonadotropin, gonadotropin releasing hormone, bovine somatotropin, porcine
21 somatotropin, oxytocin, vasopressin, GRF, prolactin, somatostatin,
lypressin,
22 pancreozymin, luteinizing hormone, LHRH, LHRH agonists and antagonists,
23 leuprolide, interferons, interleukins, growth hormones such as human growth
24 hormone, bovine growth hormone and porcine growth hormone, fertility
inhibitors
such as the prostaglandins, fertility promoters, growth factors, coagultion
factors,
26 human pancreas hormone releasing factor, analogs and derivatives of these
27 compounds, and pharmaceutically acceptable salts of these compounds, or
their
28 analogs or derivatives.
29 The beneficial agent can be present in this invention in a wide variety of
chemical and physical forms, such as solids, liquids and slurries. On the
molecular
31 level, the various forms may include uncharged molecules, molecular
complexes,
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1 and pharmaceutically acceptable acid addition and base addition salts such
as
2 hydrochlorides, hydrobromides, sulfate, laurylate, oleate, and salicylate.
For acidic
3 compounds, salts of metals, amines or organic cations may be used.
Derivatives
4 such as esters, ethers and amides can also be used. An active agent can be
used
alone or mixed with other active agents.
6 According to other embodiments of the present invention, the delivery device
7 may take different forms. For example, the piston may be replaced with a
flexible
8 member such as a diaphragm, partition, pad, flat sheet, spheroid, or rigid
metal
9 alloy, and may be made of any number of inert materials. Furthermore, the
osmotic
device may function without the piston, having simply an interface between the
11 osmotic agent/fluid additive and the beneficial agent.
12 The above-described exemplary embodiments are intended to be illustrative
13 in all respects, rather than restrictive, of the present invention. Thus
the present
14 invention is capable of many variations in detailed implementation that can
be
derived from the description contained herein by a person skilled in the art.
All
16 such variations and modifications are considered to be within the scope and
spirit of
17 the present invention as defmed by the following claims.
