Device for generating a pulsatile fluid drug flow

Details Device for generating a pulsatile fluid drug flow Device for generating a pulsatile fluid drug flow

1999-09-07

2001-11-06

Seidel, Richard K. (Department: 3763)

Surgery

Means for introducing or removing material from body for...

Treating material introduced into or removed from body...

C604S247000, C604S256000

Reexamination Certificate

active

06312409

ABSTRACT:

TECHNICAL FIELD
This invention relates to drug delivery devices and in particular to pulsatile drug delivery devices.
BACKGROUND ART
Pumps for delivering drugs to a human or animal subject range from simple cheap devices to expensive, complicated microchip-controlled devices. Amongst the cheapest and least complicated devices are osmotic and elastomeric pumps.
Osmotic pumps such as the “ALZET” (Trade Mark) pump produced by the Alza Corporation, Calif., rely on osmotic pressure developed between an aqueous environment and an osmotic solution to drive a drug from a reservoir. Elastomeric pumps such as the “INFUSOR” (Trade Mark) pump produced by Baxter Healthcare Corporation, Ill., rely on the contraction of an expanded elastomeric reservoir to drive the drug from the reservoir. Both types of pump are advantageous primarily as a result of their simplicity, cheapness and reliability. Developments in technology have led to a situation where a highly reliable rate of drug delivery can be obtained from such devices.
Similar simple devices include pumps where the contraction of the reservoir is driven by a spring, by the generation of gas in a simple electrolytic cell, or the generation of gas by a chemical reaction. Again, cheap devices having a reliable delivery rate are available using such technologies, although even in devices employing an electrolytic cell the expense and complexity is increased by the necessity of including a battery.
The primary limitation with such devices, some of which have been available since the 1970s, is that they are only suitable in situations where a steady, continuous flow of drug is desired. This immediately precludes their use where a variation in the drug flow rate is required. One particular example of such a case is if a pulsatile drug flow is desired. This method of delivering drugs has become important in recent years. A good overview of the types of situations where a pulsatile drug flow is advantageous can be found in “Pulsatile Drug Delivery—current applications and future trends” ed. Gurny, Junginger and Peppas (published by Wissenschaftliche Verlagsgesellschaft mbH, Stuttgart, 1993). One of the main reasons why pulsatile drug delivery may be advantageous is that a constant supply of drug does not always give rise to constant effects. Furthermore, the body may respond better, in the case of some drugs, to a pulsatile delivery regime.
While other devices have certainly been disclosed which can be used to effect pulsatile drug delivery, such devices in no way approach the simplicity or cheapness of the basic single rate devices referred to above. For example, the devices may rely on microprocessors or electronic timing circuits to switch delivery on and off, or they may employ continuous gas generation which is relieved periodically by a valve which snaps open to effect a periodic cyclical generation of driving pressure. These devices employ mechanisms which are in many cases less reliable than single rate devices, and they are generally significantly more expensive to produce.
The present invention seeks to overcome these disadvantages and to provide pulsatile delivery devices which are simple, cheap and can employ the existing technology which has proved successful in relation to single rate drug pumps.
DISCLOSURE OF INVENTION
Thus, the invention provides a device for generating a pulsatile fluid drug flow, comprising a housing containing an expandable-contractible chamber having an inlet and an outlet, a valve associated with the outlet which is actuated by the expansion and contraction of the chamber, and means for biasing the chamber to its contracted state, such that when the inlet is connected to a pressurised fluid drug supply the chamber is expanded by the drug, the expansion of the chamber actuating the valve to open, thereby allowing release of the drug from the chamber and enabling the contraction of the chamber under the influence of the biasing means, this contraction in turn actuating the valve to close thereby allowing the chamber to refill.
As used herein, the term, “liquid drug”, is meant to encompass any drug-containing fluid capable of being passed through the hollow needle in a controlled manner, such as a liquid, solution, gel or fine suspension. There is essentially no limitation on the type of liquid drug which can be used with the invention other than to exclude those liquid drugs which would be inappropriate to deliver to the subject intravenously, intradermally or subcutaneously. Representative drugs include peptides or proteins, hormones, analgesics, anti-migraine agents, anti-coagulant agents, anti-emetic agents, cardiovascular agents, anti-hypertensive agents, narcotic antagonists, chelating agents, anti-anginal agents, chemotherapy agents, sedatives, anti-neoplastics, prostaglandins and anti-diuretic agents.
Typical drugs include peptides, proteins or hormones such as insulin, calcitonin, calcitonin gene regulating protein, atrial natriuretic protein, colony stimulating factor, betaseron, erythropoietin (EPO), interferons such as &agr;, &bgr; or &ggr; interferon, somatropin, somatotropin, somatostatin, insulin-like growth factor (somatomedins), luteinizing hormone releasing hormone (LHRH), tissue plasminogen activator (TPA), growth hormone releasing hormone (GHRH), oxytocin, estradiol, growth hormones, leuprolide acetate, factor VIII, interleukins such as interleukin-2, and analogues thereof; analgesics such as fentanyl, sufentanil, butorphafiol, buprenorphine, levorphanol, morphine, hydromorphone, hydrocodone, oxymorphone, methadone, lidocaine, bupivacaine, diclofenac, naproxen, paverin, and analogues thereof; anti-migraine agents such as sumatriptan, ergot alkaloids, and analogues thereof; anti-coagulant agents such as heparin, hirudin, and analogues thereof; anti-emetic agents such as scopolamine, ondansetron, domperidone, metoclopramide, and analogues thereof; cardiovascular agents, anti-hypertensive agents and vasodilators such as diltiazem, clonidine, nifedipine, verapamil, isosorbide-5-mononitrate, organic nitrates, agents used in treatment of heart disorders, and analogues thereof; sedatives such as benzodiazepines, phenothiozines, and analogues thereof; narcotic antagonists such as naltrexone, naloxone, and analogues thereof; chelating agents such as deferoxamine, and analogues thereof; anti-diuretic agents such as desmopressin, vasopressin, and analogues thereof; anti-anginal agents such as nitroglycerine, and analogues thereof; anti-neoplastics such as 5-fluorouracil, bleomycin, and analogues thereof; prostaglandins and analogues thereof; and chemotherapy agents such as vincristine, and analogues thereof.
Other drugs include antiulcer agents, such as but not limited to cimetidine, and ranitidine; antibiotics; anticonvulsants; antiinflammatories; antifungals; antipsychotics; corticosteriods; immunosuppressants; electrolytes; nutritional agents and vitamins; general anesthetics; antianxiety agents, such as but not limited to compazine; and diagnostic agents.
The device according to the invention automatically generates pulses of a drug from any pressurised supply. It converts any pressurised supply into a pulsatile flow without the need for any power source and can therefore be designed as an extremely simple unpowered mechanical device. It will be appreciated that the device according to the invention can be coupled to a standard continuous drug pump and can therefore provide a simple, cheap and effective pulsatile drug source which has none of the complexity of existing variable rate powered drug pumps.
The frequency of pulsation and the volume of the pulses can be selected by the design of the device. Particular consideration can be given to the sizes of the chamber, inlet and outlet, the strength of the biasing means, the pressure and volume provided by the drug supply, the nature of the valve, and the nature of the coupling between the valve and the expansion and contraction of the chamber.
Suitably, the valve is a bistable valve which is actuated between opened and closed states.
A bistable val

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