Surgery – Controlled release therapeutic device or system – Osmotic or diffusion pumped device or system
Patent
1995-05-11
1997-12-16
Buiz, Michael Powell
Surgery
Controlled release therapeutic device or system
Osmotic or diffusion pumped device or system
424473, A61K 922
Patent
active
056979223
DESCRIPTION:
BRIEF SUMMARY
This invention relates to devices useful for the delivery of a beneficial agent to an environment of use.
There are a variety of delivery devices that incorporate osmagents in the device core. The osmagents cause an osmotic pressure gradient across the device wall and imbibe fluid into the device. Such delivery devices release their active agents either by osmotic pumping or by diffusion or by a combination of the two mechanisms. Since the active agent is released from the device as an aqueous solution, the release rate is dependent on the solubility of the active agent in water. This release rate dependence on the solubility of the active agent can inhibit the attainment of a preferred release rate profile. In order to obtain a useful release profile for poorly water soluble beneficial agents, a solubility enhancing agent may be added to the device core. Alternatively, to obtain a useful release profile for highly water soluble active agents, an excipient which decreases the active agent solubility may be added to the device core.
U.S. Pat. No. 4,755,180 ('180) describes such solubility modifying excipients and discloses coating of the excipients with a polymer coating in order to control the release of the excipient. The '180 patent discloses "osmagents" (beneficial agent solubility modifying agents) having various forms such as particles, powders and the like. Generally, the release rate controlling film has a thickness of 1 to 20 mils, and in a preferred embodiment, has a thickness of 2 to 10 mils. In addition, McClelland, Gregory A., Sutton, Steven C., Engle, Karen, and Zentner, Gaylen, M. "The Solubility-Modulated Osmotic Pump: In Vitro/in Vivo Release of Diltiazem Hydrochloride", Pharmaceutical Research, Vol. 8, No.1. (1991) disclosed the design and evaluation of a solubility-modulated controlled-porosity osmotic pump for delivery of the highly water-soluble drug diltiazem hydrochloride. Specifically, the study incorporated coated sodium chloride crystals (i.e., microosmotic pumps) into the core tablet formulation of a diltiazem hydrochloride controlled porosity osmotic pump. This pump-in-a-pump design prevented the rapid depletion, and large attendant concentration variation, of the solubility modulating agent (sodium chloride) within the diltiazem hydrochloride core tablet environment. Thus, the release of the solubility modulator was controllable and, was designed to provide modulation of the drug solubility for a prolonged period.
In another aspect of delivery devices, the use of an asymmetric membrane to coat the device core has been disclosed (E.P.O. Publication No. 0357369). That publication discloses an asymmetric membrane having two regions or membrane layers. The substructure is relatively thick and very porous in nature. This substructure supports the other portion of the membrane, a dense, thin skin.
Although there has been a significant advance in the field of controlled delivery devices, there is a continuing search for other delivery devices, particularly those which deliver poorly water soluble or highly water soluble beneficial agents.
SUMMARY OF THE INVENTION
This invention is directed to an asymmetric membrane delivery device having coated, macroparticulate, beneficial agent- solubility modifiers for use in dispensing a beneficial agent to an aqueous environment of use. The device comprises a beneficial agent, an osmagent, a macroparticulate solubility modifier and an asymmetric membrane that surrounds the device components. The solubility modifier is coated. The solubility modifier or beneficial agent may be the osmagent or there may be a separate osmagent.
Another aspect of this invention is a method for the delivery of a beneficial agent to an environment of use which comprises placing the above device into the environment of use.
These devices enable the control of the beneficial agent release profile. In particular, the large sized coated excipients provide significant advantages over smaller sized coated excipients such as facilitating the use of a greater variety of coat
REFERENCES:
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patent: 4608048 (1986-08-01), Cortese et al.
patent: 4755180 (1988-07-01), Ayer et al.
patent: 5120548 (1992-06-01), McClelland et al.
patent: 5225202 (1993-07-01), Hodges et al.
patent: 5260068 (1993-11-01), Chen
G. A. McClelland et al, "The Solubility-Modulated Osmotic Pump: In vitro/In vivo Release of Diltiazem Hydrochloride", Pharma. Research, vol. 8, No. 1, pp. 88-92 (1991).
Benson Gregg C.
Buiz Michael Powell
Nguyen At
Olson A. Dean
Pfizer Inc.
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