US3527220A - Implantable drug administrator - Google Patents

Description

United States Patent Inventor George Donald Summers Stony Brook, New York Appl. No. 741,117

Filed June 28, 1968 Patented Sept. 8, 1970 Assignee Fairchlld Hiller Corporation Farmingdale, 12.1., New York a corporation of Maryland IMPLANTABLE DRUG ADMINISTRATOR 15 Claims, 5 Drawing Figs.

U.S. Cl 128/260, 3/1, 128/15, 128/273 Int. Cl. A61m 7/00 Field of Search 128/260,

[561 References Cited UNITED STATES PATENTS 2,625,158 1/1953 Lee et a1. 128/260 3,313,289 4/1967 Kapra1.... 3/1 3,443,561 5/1969 Reed 128/260 Primary Examiner-Adele M. Eager Attorney-Michael W. York ABSTRACT: An implantable drug administrator comprises a bladder having a self-sealing port through which it can be filled with a drug, a pump for selectively pumping the drug 7 from the bladder into any desired area of the body, and an indicator for indicating when the desired amount of the drug has been injected.

Patented Sept. 8, 1970 v 3,527,220

INVENTOR GEORGE DONALD SUMMERS ATTORNEYS IMPLANTABLE DRUG ADMINISTRATOR This invention relates to a device which can be implanted within an animal body for administering drugs or the like.

It has been proposed to implant a reservoir containing a drug or other medical preparation within a body cavity for purposes of administering the drug. to an animal. In such arrangements, the drug is generally permitted to escape into the body through perforations in the container or by diffusion through the container itself.

The prior art devices for this purpose have only attained limited utility principally because of their lack of reliability due, at least in part, to clogging of the container, and the obvious inconvenience of replacing an implantable container every time its drug supply is exhausted. Further drawbacks are the inability to situate the container in any desired area of the body while releasing the drug in a distant area ofthe body, and the lack of a practical monitoring device for assuring the proper operation of the system.

The present invention provides an improved implantable drug administration system which avoids the foregoing drawbacks and therefore is more reliable, easier to use, and of wider utility than known devices of this type.

Briefly, according to the invention, a drug is pumped from an implanted bladder by means of an implanted pump which is powered by an extra-corporeal magnetic field. The bladder includes a self-sealing port through which it can be refilled whenever desired. An implanted light source indicates the rate at which the drug is being pumped and thus can also be used to indicate the total dosage administered.

In the drawings:

FIG. 1 is a diagrammatic view showing how the invention typically would be implanted within the body ofa human;

FIG. 2 is a perspective view of the invention prior to being implanted;

FIG. 3 is a circuit diagram of the indicator circuit used in the preferred embodiment of the invention;

FIG. 4 is a detailed cross-sectional view of the inlet tube of the invention illustrated in FIG. 2; and

FIG. 5 is a detailed broken sectional view of the switch and the pump ofthe invention illustrated in FIG. 2.

In the specification and claims, the term "drug" is used in the broadest sense and includes all therapeutic and diagnostic agents such as hormones, vitamins, antibiotics, anticoagulants, cancericidal and spermicidal agents, vasoactive agents, and all other substances used to control, treat, or diagnose, or otherwise affect, physical or mental conditions (normal and abnormal) existing in and/or on an animal body.

Referring to FIGS. 1 and 2, the invention is shown as comprising a bladder and a pump 12 having an inlet line 14 connected to the lowermost point of bladder 10. The bladder 10 and pump 12 may be sutured in place within the abdominal cavity 16 of an individual, with a pump outlet line 18 leading into that portion of the body where it is desired to administer the drug.

Bladder 10 includes a port 20 which is self sealing and readily accessible from outside the individuals body although the port may be underneath the skin. A miniature light source 22 is sewn to bladder 10 within abdominal cavity 16, and, when energized, can be observed through the individuals skin. As explained below, light source 22 provides an indication of the dosage or amount of the drug within bladder 10 administered by the pump 12.

In the preferred embodiment of the invention, pump 12 is of the type disclosed in the May/June 1967 issue of The Journal of the Association for the Advancement of Medical Instrumentation, in an article entitled A New Miniature Pump for the Treatment of Hydrocephalus" by Summers and Mathews. As explained in that article, pump 12 includes a rotor assembly which is coupled through a gear train to a rotatable magnetic disc. The rotor contains three peripheral rollers which cyclically compress a length of tubing between the pump inlet 14 and outlet l8 with a peristatic action, thereby forcing fluid from inlet 14 to outlet 18. Since this construction is known, it is not illustrated and described here in detail.

The pump is driven by a rotatable magnet 24 located outside the body and rotated by a motor 26 suitably coupled thereto. The rotation of magnet 24 rotates the pump magnet by the pull of its magnetic field thus pumping the drug from bladder 10 through pump inlet tube 14 and outlet tube 18. This particular pump is highly desirable since it can be powered without penetrating the skin (exclusive of implantation), the advantages of which are self-evident. The specific pump per se, however, forms no part of this invention. The manner in which the invention is employed is obvious from the preceding explanation. After the bladder 10 and pump 12 have been implanted, the drug to be administered is injected into the bladder by means of a hypodermic needle and syringe or the like inserted through the seal-sealing plug 20. Thereafter, whenever it is desired to administer the drug, the motor 26 is energized to rotate magnet 24 thus driving pump 12 as explained above. The operation of the pump will cause the drug within bladder 10 to be administered through the distal end of outlet tube 18 wherever it is positioned.

The light source 22 may be energized a predetermined number of times during each revolution of the pump rotor to indicate that the pump is operating and to provide a measure of the dosage administered.

FIG. 2 shows certain specific details of the bladder 10, pump 12 and the energizing means for lamp 22. The pump is retained within a sealed stainless steel (or plastic) casing 30 which includes a flange 32 having apertures 34 by means of which the pump may be sewn into the body. A coil 36 is wrapped around a diameter of casing 30, with the coil leads 37 and 38 coupled, respectively to a miniature switch 40 within casing 30 and to the-lamp 22. Switch 40 (shown diagrammatically in FIG. 3) is a single-pole, single-throw (normally open) switch which can be closed in any suitable fashion each time a roller of the pump rotor traverses the pump tubing between inlet 14 and outlet 18. The operation of a preferred embodiment of switch 40 is explained below with reference to FIG. 5.

When the magnet 24 is rotated by motor 26, the resultant rotating magnetic field intersects coil 36 inducing a current in the coil. Accordingly, each time the contacts of switch 40 are closed, an energizing current is coupled to the light source 22. Thus, the energization of the light, which can be seen through the skin, indicates that the pump is operating properly. Since the volume amount of the drug displaced between successive rollers by rotation of the pump rotor is known, the flashes of light source 22 can be counted to measure the total administered dosage of the drug.

The bladder 10 includes an inner layer 50 coated with an outer layer 52 which is compatible with animal tissue. Various silicone rubber compositions are suitable for use as layer 52, representative examples being given in US Pat. No. 3,279,996 of Long. Since diffusion may occur through a silicone rubber layer, the inner layer 50 must be impervious to and not degraded by the drug used. Standard latex rubber is suitable for many purposes as the material of inner layer 50. The use of the silicone rubber layer provides a degree of selfsealing in the event the bladder is accidentally punctured during filling.

The self-sealing port 20 comprises a ring 54 made of a tissue compatible material such as a polycarbonate resin or stainless steel filled with a silicone rubber material 56 to a depth of about .25 inches. If necessary, an inner layer (not shown) of a material impervious to the drug may be used. The raised ring 54 enables the doctor to locate the port 20 through the skin. Where ring 54 is made of magnetically permeable material it can be located by a common stud finder or the like.

A stiff plastic or metal striker plate 58 is bonded to the interior layer 50 opposite port 20 as protection against accidental puncture of the bladder during injection of the drug. To ensure injection of the drug into the bladder, the inner surface of the port may be made concave so that there will always be a space between the port and striker plate 58.

As noted previously, the invention is not limited to any specific drug, and the drugs may be administered directly into tissue, organs, muscle, or body fluid (including blood). The

particular function in this respect will determine the size and construction of the needle or other termination of the outlet tube 18. As a specific example tube 18 may terminate in a rounded end 62 having side slots 64 through which the drug is dispensed. This construction will tend to prevent body fluid from entering tube 18 without interfering with the exit of the drug. A woven tube 66 (for example, of Dacron) may be bonded to the exterior surface of tube 18. Animal tissue will grow into tube 66 to help anchor the tube in the desired area of the body and to seal the penetration site against flow of body fluids.

The light source may comprise a diode made of gallium arsenide phosphide, requiring a forward bias of about 1.5 to 2.0 volts. It is less than a tenth of an inch in diameter and has an overall length of about an eighth of an inch, including the lens cap. It is rated at 50 foot-Lamberts brightness at a forward bias of 1.65 volts and forward current of 50 milliamperes. At that voltage it has a continuous forward current rating of 100 milliamperes.

In order to achieve maximum optical transmission through the skin, it is desirable to choose a wavelength in the zone of greatest skin transparency. However, this wavelength would be unsuitable as maximum transparency lies in the near-infrared region and is not visible to the human eye. On the other hand, the region of maximum sensitivity of the light-adapted human eye, about 570 millimicrons, is poorly transmitted through the skin. The wavelength of the selected lightemitting diode, in the 600-to-700 millimicron region, provides a compromise. The skin is reasonably transparent at this wavelength and the eye can easily detect the rich red color.

Some data on the depth of penetration of optical frequencies into the human have been reported. Penetration depth varies with skin pigmentation and is in the range of about two millimeters maximum. Data for transmission outward is not available, but in experiments the diode-emitted light was easily visible in a darkened room through chicken skin and tissue for depths of more than 8 millimeters. I

The energizing circuit for light source 22 is shown in FIG. 3. It is a simple series circuit and also includes a protective diode 70 which prevents the application of excessive back voltages to the light source 22.

In place of the coil 36, the power to operate lamp 22 may be provided by a battery or photo-voltaic cells. Also the coil 36 may be made responsive to an inductive or RF electromagnetic field.

In the preferred embodiment of the invention, the electrical leads are covered with an insulating material 72 (FIG. 4) such as Teflon and the solder joints coated with an epoxy (not shown). The wires are then bonded to the inlet tube 14 and the entire construction coated with a suitable silicone rubber composition 74.

A preferred construction for switch 40 is shown in FIG. 5. The pump includes a steel ring 80 within the pump casing 30. The pump rollers (one of which is shown at 82) compress the tubing 84 between inlet and outlet tubes 14 and 18 against ring 80. Switch 40 thus comprises the ring 80, a pressure sensitive paint 86, and a terminal 88 which is insulated from ring 80. The switch leads 37 and 37 are mechanically coupled through casing 30 (and suitably sealed) into electrical contact with ring 80 and terminal 88, respectively.

Paint 86 is ofa type which undergoes an increase in conductivity upon application of pressure thereto. (A suitable paint of this type is manufactured by Clark Electronics Laboratories of Palm Springs, California and sold under the trademark Micro-Ducer (type 9A).) Thus, each time a roller 82 passes over the terminal 88, the resultant increase in pressure closes" switch 40 to energize the light source 22.

Obviously, other switch constructions may be employed with the invention. A magnetically actuated mechanical switch would be of particular utility since it would enable a simple means for testing whether the signalling system was in proper working order by applying an external magnetic field to latch the switch in its closed condition. If, because of the magnetic fields required to operate pump 12, such a switch could not be employed in place of switch 40, a normally open switch of this type could be located at the bladder 10 and placed electrically in parallel with the contacts of switch 40. Such a switch is shown in dotted lines at in FIG. 3.

The visual signalling system of the invention would have utility in other applications apart from the specific case herein illustrated. For example, it could be used to test the continuity of circuits where breakage or interruption of leads is a problem (as with cardiac pacemakers).

Use of the invention is specifically contemplated in the treatment of diabetics or for chemotherapy of a carcinomatic condition. It could be used for the daily administration of a contraceptive, in the treatment of Hansens disease and in the administration of some hormones..The invention, however, is not in any respect limited as to its utility in special situations.

It is intended that the various parts of the invention will be sealed and coated with a tissue compatible material (such as silicone rubber) to whatever extent is required. Since silicone rubber is not a sealant, it may be necessary or desirable to coat the parts with a sealant (e.g. an epoxy) prior to applying the silicone rubber coating.

The invention can be used in many different ways to inject varying amounts of a drug ranging, for example, from microliters per day to milliliters per day. It can be used continuously and, conceivably, actuation of the pump may be made automatically responsive to a measurable body condition (e.g. oxygen partial pressure in the blood) or responsive to a programmed time schedule. The pump rotor can be made to rotate in both directions whereby a single pump can be used in conjunction with two bladders (and suitable valves) to selectively pump drugs from either bladder.

Iclaim:

1. An implantable drug administrator for injecting a drug into an animal body comprising a bladder adapted to be implanted in the body having self-sealing means for permitting a drug to be injected into the interior of said bladder and a pump adapted to be implanted in the body for pumping the drug from said bladder, said pump having an inlet connected to said bladder and an outlet adapted to be positioned within said body.

2. An implantable drug administrator according to claim 1 wherein said self-sealing means comprises a port.

3. An implantable drug administrator according to claim 2 wherein said port includes a protruding ring.

4. An implantable drug administrator according to claim 2 including a striker plate bonded to said bladder in the area beneath said port.

5. An implantable drug administrator according to claim 2 wherein said port includes a magnetically permeable material.

6. An implantable drug administrator according to claim 1 including means connected to said pump for indicating the rate at which said pump is operating.

7. An implantable drug administrator according to claim 6 including means for testing the operation of said indicator means.

8. An implantable drug administrator according to claim 6 wherein said indicating means includes a coil for producing a current in response to a field exterior of said body.

9. An implantable drug administrator according to claim 8 wherein said pump is adapted to be operated by a magnetic field and said coil is wound around said pump to intersect said magnetic field.

- 10. An implantable drug administrator according to claim 8 wherein said indicating means includes a light source connected in circuit with said coil.

11. An implantable drug administrator according to claim 10 including a switch connected in circuit with said coil and said light source, said switch being adapted to be activated in response to the operation of said pump.

12. An implantable drug administrator according to claim 11 wherein said pump includes a rotor, and said switch is adapted to be activated by said rotor.

13. An implantable drug administrator according to claim 12 wherein said pump includes an outer casing and said switch is mounted within said casing.

14. An implantable drug administrator according to claim

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