Transdermal absorption of bupranolol in rabbit skin in vitro and in vivo

This study was designed to clarify the percutaneous penetration of bupranol ol (BP), a beta -adrenoceptor antagonist, through rabbit skin and to compar e the in vitro penetration with the in vivo absorption. BP penetrated acros s the skin slowly in the absence of enhancers in vitro. Isopropyl myristate and N-methyl-2-pyrrolidone enhanced the in vitro penetration, with a 3.6 t imes higher flux compared with that without enhancers. However, in the in v ivo percutaneous absorption, the maximal penetration was obtained with the formulation added d-limonene, with a 3.0 times higher area under the concen tration-time curve (AUC) than that for the formulation without enhancers. T he plasma levels of BP determined, however, were extremely lower than the t heoretical plasma steady-state concentrations predicted. The plasma levels of BF after application of these formulations were maintained in the range of 7-22 ng/ml for 30 h, of a which concentrations were above the therapeuti cally effective concentration (1.5-4 ng/ml). Therefore, the transdermal sys tems will offer an efficient drug delivery system for the treatment of angi na pectoris and tachycardia.