Controlled drug release from a novel liposomal delivery system. I. Investigation of transdermal potential

Victoria M. Knepp, Robert S. Hinz, Francis C. Szoka, Richard H. Guy

Research output: Contribution to journalArticlepeer-review


The in vitro release behavior of a novel liposome-based drug delivery device has been characterized. The system consists of a molded agarose matrix in which the model drug (progesterone) was dispersed either free or associated with one of four lipid formulations: egg-phosphatidylcholine (EPC) liposomes, EPC/cholesterol (2:1) liposomes, Intralipid® emulsion, and dipalmitoylphosphatidylcholine (DPPC) liposomes. Drug release rates from the devices into aqueous buffer were measured at 37° C. The free progesterone release rate decreased rapidly over 24 h with over 90% delivered. The liposomal patches, on the other hand, imposed apparent zero-order kinetics: for example, both the EPC and DPPC systems delivered their progesterone payloads at about 1%/h over 24 h. Further, the EPC and DPPC patches significantly slowed transdermal drug delivery across excised hairless mouse skin. The EPC device retarded throughput to one-half the control value, the DPPC system reduced the transport kinetics by an order of magnitude. The results support two hypotheses: (a) the liposomal-based reservoir system can modulate drug input via the skin, (b) the zero-order release of progesterone from liposomes is determined by slow interfacial transport out of the bilayer into the surrounding aqueous medium.

Original languageEnglish
Pages (from-to)211-221
Number of pages11
JournalJournal of Controlled Release
Issue number3
Publication statusPublished - 31 Dec 1987

Bibliographical note

Funding Information:
Principal funding was provided by Liposome Technology Inc., Menlo Park, CA. Additional support was received from the Donors of the Petroleum Resarch Fund, administered by the American Chemical Society (PRF#17438-AC7). We thank Professors Gordon Flynn, Norman Weiner, and Ronald Siegel for helpful insight and discussion, and Andrea Maze1 for preparing the manuscript. Preliminary accounts of this research were presented at the 39th National Meeting of the Academy of Pharmaceutical Sciences, A.Ph.A., Minneapolis, MN, 1985 and at the 191st National Meeting of the American Chemical Society, New York, NY, 1986.

ASJC Scopus subject areas

  • Pharmaceutical Science


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