Background and Purpose. Pharmacokinetic assessment of drug tissue permeatio
n following iontophoresis is limited. The depth of ketoprofen tissue permea
tion following cathodic iontophoresis (4 mA, 40 minutes) and the stereosele
ctivity of drug delivery were examined in this study. Subjects. Ketoprofen
(750 mg) was iontophoresed onto one porcine medial thigh, with passive drug
permeation conducted on the other thigh. Methods. Skin, subcutaneous fasci
a, and muscle biopsies from the drug delivery sites were harvested and stor
ed separately, and the "R" and "S" ketoprofen enantiomers were determined.
Results. Iontophoretic and passive applications yielded equivalent total ke
toprofen concentrations in the skill and fascia. in contrast, multivariate
analysis demonstrated that the ketoprofen concentration in the first centim
eter of muscle following iontophoresis was greater than the drug concentrat
ion in the deeper underlying muscle layers and greater than that delivered
to any muscle layer following passive delivery. No transcutaneous stereosel
ective delivery of ketoprofen was detected. Conclusion and Discussion. Comp
ared with passive delivery, iontophoresis enhances nonstereoselective ketop
rofen permeation into the fascia-muscle interface. With delivery to deeper
tissue sites, however, there is no apparent enhancement over passive applic
ation.