In Vitro Evaluation of Niosomal Gel Containing Pilocarpine Hydrochloride for Ocular Delivery

The present study was focused on formulating and evaluating niosomal gel formulations for ocular controlled delivery of a cholinergic drug; pilocarpine HCl. Pilocarpine HCl loaded niosomes were prepared using various non-ionic surfactants (span 20, span 60, and span 80), in the presence of cholesterol in different molar ratios by ether injection method. The prepared vesicles were evaluated for entrapment efficiency, vesicle size, zeta potential, in vitro release and morphology by transmission electron microscopy (TEM). The selected formulations were incorporated into carbopol 934 (1% w/w) and locust bean gum (3% w/w) based gels. The niosomal gel formulations were characterized for isotonicity and in vitro drug permeation. In addition, stability studies of the selected niosome and gel formulation were done. The results confirmed that the niosomes formed were white and spherical in shape and have a definite internal aqueous space with uniform particle size. A formulation F4 composed of span 60 and cholesterol (1:1) gave the highest entrapment (93.26 +/- 1.75%) and release results after 8 h (Q8h = 60.35 +/- 1.87%) as compared to other formulations. The in vitro drug release studies showed that there was a slow and prolonged release of drug from niosomal gel formulations as compared to niosomes itself. The gel formulation G2 showed slower drug release (Q8h = 50.13 +/- 0.81%) due to high gelling capacity. The stability studies revealed that the selected formulation (G2) has higher stability as compared to niosomes itself. It was concluded from the study, that the niosomes containing gels may be considered as promising ocular carriers for the ocular controlled delivery of pilocarpine HCl.