Device for dispensing a liquid particularly useful for delivering medicaments at a predetermined rate.

Abstract: A device for dispensing a liquid, particularly a medicament, at a predetermined rate, comprises a container (2) including a displaceable partition (4) to define a first expansible-contractible chamber (2a) on one side for receiving the liquid (6) to be dispensed, and a second expansible-contractible chamber (26) on the opposite side for receiving an electrolytic cell (8). The electrolytic cell has electrodes (8a) and an electrolyte (8b) capable of generating, upon the energization of the electrodes (8a), a gas under pressure to thereby displace the displaceable partition (4) and to force the liquid (6) out from the first chamber (2a) in accordance with the rate of energization of the electrodes (8a).

Description: The present invention relates to a device for dispensing a liquid. The invention is particularly useful for delivering medicaments at predetermined rates, and is therefore described below with respect to this application. There are many applications requiring the dispensing or delivering of a liquid at predetermined or precisely controlled rates. One of the applications requiring particularly precise rates of delivery is in systems for administering insulin or other medicaments, and very precise pumps have been devised for this purpose. However, such pumps are expensive to produce and maintain, and are inconvenient to refill with the periodic dosage requirements. Various types of electrolytic or electrochemical pumps have been proposed for dispensing the liquid at a predetermined rate as controlled by the electrical current supplied to the electrolytic or electrochemical pump. US-A-3115280, EP-A-0 209 644 and WO-A-8 800 065. The latter publication discloses a device for dispensing a liquid at a predetermined rate, comprising a container for receiving a supply of the liquid to be dispensed; means for subjecting the liquid to a pressurized gas to force liquid from the container, said means comprising an electrolytic cell having electrodes and an electrolyte capable of generating the pressurized gas in accordance with the rate of energization of the electrodes; and a piston assembly movable within the container and dividing it into a first expansible-contractible chamber for receiving the liquid to be dispensed, and a second expansible-contractible chamber for receiving the pressurized gas to dispense liquid from the first chamber of the container. Such a device will hereinafter be referred to as a device of the kind specified. An object of the present invention is to provide a device of the kind specified but including protection against inadvertent mixing of the gas from the pressurized, second expansible-contractible chamber with the liquid to be dispensed from the first expansible-contractible chamber, e.g., because of an imperfect seal in the piston assembly between the two chambers. According to the present invention, there is provided a device of the kind specified, characterized in that the piston assembly comprises a pair of pistons spaced apart by a connecting stem, and in that the container is formed with a vent opening in the space between said pistons to provide protection against inadvertent mixing of the gas from the second chamber with the liquid in the first chamber. According to further features in the preferred embodiments of the invention described below, the second expansible-contractible chamber includes an electrolytic cell having electrodes adapted to be electrically energized, and an electrolyte capable of generating, upon the energization of the electrodes, the gas to thereby dispense the liquid from the container in accordance with the rate of energization of the electrodes. The electrolyte of the electrolytic cell may be of any appropriate material, preferably of liquid or gel form, which generates a gas upon the energization of the electrodes and in accordance with the rate of energization of the electrodes. Examples of electrolytes which may be used include saline solution or other polar solutions or gels generating hydrogen, oxygen, nitrogen or carbon dioxide. Further features and advantages of the invention will be apparent from the description below. The invention is herein described, by way of example only, with reference to the accompanying drawings, wherein: Fig. 1 is a longitudinal sectional view of the pumping unit in one form of medicament delivery device constructed in accordance with the present invention; and Fig. 2 illustrates a complete medicament delivery device including the pumping unit of Fig. 1. The medicament delivery device illustrated in Fig. 1, generally designated 300, includes a piston assembly 304 serving as a displaceable partition member within a container 302 dividing it into a drug-receiving chamber 302a and an electrolytic cell chamber 302b. Piston assembly 304 includes two pistons 304a and 304b spaced apart by an axially extending stem 304c joining the two pistons. In addition, container 302 is formed with one or more vent openings 303 in the space between the two pistons 304a, 304b. This construction isolates the drug in chamber 302a from the electrolyte 308b in chamber 302b, and also from the gas generated within that chamber by the energization of the electrodes 308a, since such electrolyte or gas, if it does penetrate past piston 304b, will be vented to the atmosphere via vent openings 303. Fig. 2 illustrates a complete medicament delivery device utilizing the double-piston construction of Fig. 1. Thus, the syringe needle 314, including its fitting 315, is adapted to be attached to fitting 316 closing the end of the drug-receiving chamber 302a. The syringe needle 314 is connected to fitting 316 via another flexible tube 318, the latter tube including a piercing element for piercing a sealing membrane 310, Fig. 1, to permit the delivery of the drug from chamber 302a to the syringe needle 314. Fig. 2 also illustrates a power supply unit 330 attachable to the fitting 324 at the opposite end of container 302 for energizing the electrodes within the electrolytic cell compartment 302b which generate the propelling gas. The power supply unit 330 includes a battery for energizing the electrodes 308a, a control circuit for controlling the energization of the electrodes, and a presetting knob 336 for presetting the rate of energization of the electrodes, and thereby the rate of delivery of the drug from compartment 302a.

Claims: A device for dispensing a liquid at a predetermined rate, comprising: a container (302) for receiving a supply of the liquid to be dispensed; means (308a, 308b) for subjecting the liquid to a pressurized gas to force liquid from the container said means comprising an electrolytic cell (302 b) having electrodes (308 a) and an electrolyte (308 b) capable of generating the pressurized gas in accordance with the rate of energization of the electrodes; and a piston assembly (304) movable within said container and dividing same into a first expansible-contractible chamber (302a) for receiving the liquid to be dispensed, and a second expansible-contractible chamber (302b) for receiving the pressurized gas to dispense liquid from said first chamber of the container; characterized in that said piston assembly (304) comprises a pair of pistons (304a, 304b) spaced apart by a connecting stem (304c), and in that said container (302) is formed with a vent opening (303) in the space between said pistons to provide protection against inadvertent mixing of the gas from said second chamber with the liquid in said first chamber. The device according to Claim 1, wherein said second expansible-contractible chamber (302b) includes an electrolytic cell having electrodes (308a) adapted to be electrically energized, and an electrolyte (308b) capable of generating, upon the energization of the electrodes, the gas to thereby dispense the liquid from the container in accordance with the rate of energization of said electrodes. The device according to Claim 2, wherein the end of said container through which the liquid is to be dispensed is closed by a membrane (310) pierceable by a needle to permit dispensing the liquid. The device according to any one of Claims 1-3, further including an electrical power supply (330) for energizing said electrodes, said electrical power supply being housed within a separate power supply unit attachable to said container. The device according to Claim 4, wherein said power supply unit (330) includes a battery and an electrical control circuit for controlling the rate of energization of the electrodes, and thereby the rate of dispensing the liquid from the container. The device according to Claim 5, wherein said electrical control circuit includes presettable means (336) for presetting the rate of energization of the electrodes.

Inventors: GROSS JOSEPH, ZUCKER SHLOMO, GROSS, JOSEPH, ZUCKER, SHLOMO
Applicants: SCIENT INNOVATIONS LTD, S.I. SCIENTIFIC INNOVATIONS LTD.
Application year: 1990
Main classification: A61M5
IPC codes: A61M5