Proniosomal gel-mediated transdermal delivery of bromocriptine: in vitro and ex vivo evaluation

Vesicular systems endow large opportunities for the transdermal delivery of therapeutics. The present study was designed to investigate the potential of a novel class of vesicular system proniosome' as a carrier for transdermal delivery of bromocriptine (BCT). Proniosome formulations were prepared by the coacervation-phase separation method and the influence of factors like surfactant type and its amount, lipid concentration, cholesterol amount and drug content were studied. Span 60 was the most appropriate surfactant, and yielded vesicle size and percentage encapsulation efficiency of 1.3 mu m and 98.9%, respectively. The developed system was characterised w.r.t. morphology, transition temperature, drug release, skin permeation and skin irritancy. Proniosomes exhibited a sustained release pattern of BCT in vitro. Skin permeation study revealed high penetration of proniosomes with sustained release of BCT through rat skin. The optimised proniosomal formulation showed enhanced transdermal flux of 16.15 g/cm(2)/h as compared to 3.67 g/cm(2)/h for drug dispersion. The developed formulations were observed as non-irritant to the rat skin and were found as quite stable at 4 and 25 degrees C for 90days w.r.t. vesicle size and drug content. The dried proniosomal formulation could act as a promising alternative to niosomes and preferably for transdermal delivery of BCT.