In vitro transdermal iontophoretic delivery of penbutolol sulfate.

Iontophoretic transport of penbutolol sulfate across porcine ear skin was studied. Passive transdermal flux of the drug in phosphate-buffered saline was 7.65 microg/cm(2) hr. There was statistically significant flux enhancement when direct current iontophoresis was applied. Iontophoresis (0.11 mA/cm(2), 0.17 mA/cm(2), and 0.22 mA/cm(2)) for 6 hr, resulted in net transport of 87.36 microg/cm(2), 137.51 microg/cm(2), and 201.12 microg/cm(2) of penbutolol sulfate, respectively. After 24 hr, cumulative amount of penbutolol transported were 201.63, 300.76, and 359.98 microg/cm(2), respectively. There was a 2.20- (0.11 mA/cm(2)), 3.26- (0.17 m/Acm(2)), and 4.28-fold (0.22 mA/cm(2)) enhancement in transcutaneous steady-state flux values compared to passive delivery. Steady-state fluxes of penbutolol sulfate also increased proportionally to current density. Steady-state fluxes calculated from the linear portion of the cumulative amount versus time curves for penbutolol sulfate were 16.68, 24.97, and 32.76 microg/cm(2)/hr at current densities of 0.11, 0.17, and 0.22 mA/cm(2). This study provides initial evidence for the potential use of iontophoresis for enhanced transdermal delivery of penbutolol sulfate.