Drug Delivery Systems: Design Criteria

  • Donald R. Cowsar
Part of the Polymer Science and Technology book series (POLS, volume 8)


In the context of the current state of the art, a controlled release drug delivery system is a combination of drug and excipient, commonly a polymeric material, arranged to allow delivery of the drug to the target at controlled rates over a specified time. The polymeric material may be either biodegradable or nonbiodegradable, and the drug may be released by diffusion of the drug through the encapsulating polymer matrix, by erosion of the polymer matrix, by a combination of diffusion and erosion, or by an alternative physical phenomenon such as capillary flow through wicks of fluid-filled devices and displacement by physiological fluids. The physical forms of the controlled release doses can vary considerably and currently include macrocapsules or pellets that are implanted via incision or trocar, microcapsules or micro-particles that are injected via a syringe; envelopes, films, or laminates that are placed in the cul-de-sac of the eye or in the oral cavity, or are implanted subcutaneously; various ring- and T-shaped intravaginal and intrauterine devices; and bandages for topical and transdermal delivery.


Dosage Form Polylactic Acid Control Delivery Contraceptive Steroid Female Reproductive Organ 


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  1. 1.
    Tanquary, A. C. and Lacey, R. E., Eds., in Controlled Release of Biologically Active Agents, Adv. Exp. Med. Biol. 47, 1974.Google Scholar

Copyright information

© Plenum Press, New York 1975

Authors and Affiliations

  • Donald R. Cowsar
    • 1
  1. 1.Southern Research InstituteBirminghamUSA

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