Development of a novel vesicular system using a binary mixture of sorbitan monostearate and polyethylene glycol fatty acid esters for rectal delivery of rutin

Abstract

Anorectal diseases, such as hemorrhoids, are bothersome benign conditions that warrant special attention. The design of an optimized vesicular system for localized rectal delivery can be a suitable conservative treatment. The feasibility of preparing proniosomes using different types of Gelucires®, in combination with Span(®) 60 as binary mixtures of nonionic surfactants, was checked, then the prepared proniosomes using Span 60 or Span 60/Gelucire were compared to conventional niosomes through investigations comprising the following: encapsulation efficiency (EE%); particle-size analysis; transmission electron microscopy; zeta potential (Z), and in vitro release study and ex vivo permeation study using excised rat rectum. All preparations showed satisfactory stability (Z >30 mV), particle size <300 nm with niosomes showing the lowest EE%, and the largest particle size, together with the least amount of drug released or accumulated in the rectal walls. Span 60/Gelucire proniosomes exhibited lower particle size as well as better release and permeation results, compared to Span 60 proniosomes. Span 60/Gelucire 44/14 (2:1) proniosomes attained the highest percentage of drug released (98.39%) and drug deposition in the rectal walls (86.26%) after 8 hours, which therefore seems to be the most suitable formula able to achieve targeted therapeutic efficacy, aiming to improve the patient's quality of life.