Formulation and Characterization of Ethosomes for Transdermal Delivery of Clarithromycin

Topical drug delivery systems such as ethosomal gels have gained prominence due to their dual-release control mechanism. The present study aimed to formulate and evaluate an ethosomal gel containing clarithromycin to enhance its transdermal permeation. Clarithromycin-loaded ethosomes were prepared using varying concentrations of phospholipids and ethanol, and characterized for vesicle size, shape, zeta potential, entrapment efficiency, and in vitro drug release using a cellophane membrane. The optimized ethosomes were incorporated into a gel base using Carbopol 974. The resulting ethosomal gels were assessed for pH, spreadability, viscosity, drug content, and drug release behavior. Among the formulations, F6 exhibited optimum physical characteristics with an entrapment efficiency of 81.2%, vesicle size of 4069 nm, zeta potential of 1.36 mV, and a polydispersity index of 0.316. In vitro drug release studies showed a cumulative release of 89.98 µg/cm² over 8 hours, while ex vivo studies using pig skin demonstrated a release of 80.11 µg/cm². The formulation also showed maximum stability under storage at 25 ± 2 °C and 60% relative humidity. These findings support the potential of ethosomal gels as effective carriers for the topical delivery of clarithromycin.