In vivo percutaneous penetration/absorption

Abstract

The objectives of the workshop were to review the relevant literature and to address in detail: (1) In vivo percutaneous penetration/absorption methodology; (2) The characteristics of dosage forms designed for application to the skin; (3) Critical factors controlling in vivo drug transport into and across the skin: (4) The use of models in the assessment and evaluation of in vivo percutaneous penetration/absorption; and (5) Bioavailability/bioequivalencc considerations for topical drug products. Scientific knowledge and technology are rapidly evolving in the topical and transdermal drug products area. This report focuses on the methodologies available for the measurement of percutaneous penetration in vivo; each scientific approach is discussed briefly followed by advantages and disadvantages of the methodology.

Pig Ear Skin ex Vivo as a Model for in Vivo Dermatopharmacokinetic Studies in Man

“…On the one hand, for corticosteroids, the vasoconstriction assay (9) has been deemed an acceptable approach to compare innovator and generic products (11,12). On the other, for almost all other drugs used topically, the problem remains unresolved because an easily visualized pharmacodynamic response is not elicited (16).…”

In Vivo Methods for the Assessment of Topical Drug Bioavailability

“…After much discussion ( 31 , 68 – 71 ), a draft guidance was published by the US Food and Drug Administration (FDA) in 1998 ( 21 ) in which the general procedures for conducting a bioavailability/bioequivalence study were described. Briefly, the guidance proposed the following steps: After application of a drug product for a given application time, excess formulation was to be removed by an appropriate (but not specified) procedure.…”

A History of Biopharmaceutics in the Food and Drug Administration 1968–1993

“…This batch-batch uniformity testing for assuring bioequivalence was also an issue for cream and ointment dosage forms. Workshops were held to address that issue (38) as well as percutaneous bioavailability and bioequivalence (39). Because of questions about the analytical methodology employed in conducting these studies, it too was explored in a separate workshop (40).…”