Percutaneous penetration enhancement in vivo measured by attenuated total reflectance infrared spectroscopy.
A novel application of attenuated total reflectance IR spectroscopy (ATR-IR) was used to monitor the outer several microns of the stratum corneum (SC) and, thereby, demonstrate enhanced percutaneous absorption in vivo in man. 4-Cyanophenol (CP) as a model permeant yielded a unique IR signal, distinct from those of the stratum corneum and the vehicle components. CP was administered for 1, 2, or 3 hr as a 10% (w/v) solution either in propylene glycol or in propylene glycol containing 5% (v/v) oleic acid. The absorbance at 2230 cm-1, which corresponded to C identical to N bond stretching, diminished significantly faster when CP was codelivered with oleic acid. An IR absorbance due primarily to propylene glycol at 1040 cm-1 (C-O stretching) also disappeared more quickly following application of the enhancer-containing solution. In addition, only the formulations with oleic acid induced a higher wavenumber shift in the frequency of the asymmetric C-H bond stretching absorbance. This change indicates increased lipid-chain disorder, the mechanism by which oleic acid is believed to cause enhanced drug transport across the stratum corneum. Therefore, ATR-IR permits one to examine noninvasively the kinetics, extent, and mechanism of percutaneous penetration enhancement in vivo in human subjects.
Mak
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VH
Department of Pharmacy, University of California, San Francisco 94143.
Potts
R O
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Guy
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RH
D000328:Adult; D006801:Humans; D008954:Models, Biological; D019301:Oleic Acid; D009829:Oleic Acids / Q000494:pharmacology; D010636:Phenols / Q000493:pharmacokinetics; D012869:Skin Absorption; D013055:Spectrophotometry, Infrared
D009829:Oleic Acids; D010636:Phenols; C007178:4-cyanophenol; D019301:Oleic Acid