Partitioning Behavior of Gemifloxacin in Anionic, Cationic and Nonanionic Surfactants. Calculation of Dermal Permeability Coefficient

Transdermal delivery acts as an alternative to oral delivery of drugs and possibly provids also an alternative to hypodermic injection. Transdermal delivery when compared to oral route has a variety of advantages namely: avoiding the degradation of drugs in the stomach environment, providing steady plasma levels, avoiding first-pass metabolism, increaseing patient compliance, easy to use, non-invasive and inexpensive, increasing the therapeutic index with a simultaneous decrease in drug side effects. Despite these advantages, one of the greatest challenges to transdermal delivery is that only a limited number of drugs are amenable to administration by this route. Gemifloxacin, a broad spectrum fourth generation quinolone antibacterial agent has pharmacokinetic characteristics (particularly its low maximum plasma concentration, obtained following repeat oral dose of 320 mg) that makes it a potential target for transdermal delivery. The objective of the study was to explore the possibility of surfactants (anionic, cationic and nonionic) acting as dermal enhancers of gemifloxacin assuming that the drug is to be formulated into topical or transdermal pharmaceutical dosage form. To accomplish the objective, gemifloxacin was partitioned between chloroform and surfactants containing varying concentrations of sodium lauryl sulfate, cetyltrimethylammonium bromide, polysorbate-20 and polysorbate-80. The data obtained were used to estimate the dermal permeability coefficient. The partitioning was carried out by shake flask method at room temperature. It was observed that all the surfactants decreased the partition behavior of gemifloxacin when compared to that of water alone. Sodium lauryl sulfate produced the most decreasing partition effect at the highest concentration studied (2% w/v). The permeability coefficient (Kp) was estimated from the partition coefficient data and the molecular weight of the drug. As permeability coefficient is an important descriptor for evaluating dermal absorption of drugs employed in clinical treatment of various dermal accessible ailments, the results of the study suggest that the investigated surfactants might not be potential transdermal enhancers of gemifloxacin.