Effect of stearylamine on the physicochemical properties of liposomal formulations containing timolol maleate for ophthalmic application

Liposomes are widely investigated drug delivery systems because of their biocompatibility, ability to encapsulate hydrophilic and lipophilic compounds, and capacity to prolong drug release. In ophthalmic delivery, liposomes may improve drug retention on the ocular surface and reduce the rapid precorneal elimination associated with conventional eye drops. Such systems have attracted increasing interest as potential carriers for ocular drug delivery. Stearylamine is a positively charged lipid capable of modifying membrane properties and influencing interactions with negatively charged ocular structures. The aim of the present study was to develop and characterize liposomal formulations containing graded concentrations of stearylamine and to evaluate its effect on the physicochemical properties of liposomes containing timolol maleate. The formulations were characterized in terms of particle size, zeta potential, encapsulation efficiency, release profiles, and stability.