Development and characterization of niosomes loaded mucoadhesive biodegradable ocular inserts for extended release of pilocarpine HCl

Abstract

Background Pilocarpine HCl is a non-selective muscarinic receptor agonist that is prescribed for the treatment of glaucoma. The use of pilocarpine conventional eye drops is associated with several side effects, such as loss of visual acuity, and the need for several applications due to rapid drainage away via the nasolacrimal duct, especially for elderly people. Such adverse effects can lead to low patient compliance and poor clinical outcomes. Therefore, the aim of this project was to develop, optimise and characterise a biodegradable pilocarpine HCl ocular insert using niosomes as a drug delivery vehicle. To achieve that, various polymers such as hydroxypropyl methylcellulose (HPMC), polyvinyl alcohol (PVA), and a blend of both were investigated to prepare the ocular inserts using solvent casting technique. The niosomes of pilocarpine HCl were prepared using span-60 and cholesterol by thin film hydration method. The produced noisome-loaded ocular inserts were characterised using various analytical techniques, including Fourier Transform Infrared (FTIR), X-ray Diffractions (XRD), thermal analysis, particle size analysis, weight and content uniformity, surface pH and drug release profile, among others. Results The results indicated that drug-free ocular inserts of the two polymers (HPMC + PVA) were better than single polymer-based ocular inserts (HPMC or PVA alone). The formed niosomes demonstrated good entrapment efficiency of 49.7% ± 7.0, with an average particle size of 325.7 ± 3.5 nm. The FTIR analysis showed no interaction between the compositions of niosomes. Four optimal formulations with various co-polymer ratios and pilocarpine content were further evaluated. Pilocarpine-containing niosomes-loaded ocular inserts provided uniformity in pilocarpine content (89–96%), with 34.8% moisture content and an average pH of 7. The release profile of niosomes-loaded inserts demonstrated an initial burst release within 2 h ranging from 26.54% (T4) to 41.22% (T2), and continuous sustained release for the next 24 h (68.32 ± 5.11% (T4) to 82.11 ± 6.01% (T2)). Conclusions This work successfully optimised biodegradable ocular inserts containing slow-release pilocarpine HCl encapsulated in niosomes for the treatment of glaucoma without dose dumping, resulting in a user-friendly drug delivery system. Graphical abstract