The present study was focused on investigating niosomal gels loaded with cholinergic drug; pilocarpine HCl, for prolonged precorneal residence time and improved bioavailability for glaucoma treatment. Pilocarpine HCl niosomes were prepared using various nonionic surfactants (span 20, span 60 and span 80), in the presence of cholesterol in different molar ratios by ether injection method. The selected formulations were incorporated into carbopol 934 and locust bean gum-based gels. TEM analysis confirmed that niosomes formed were spherical in shape and has a definite internal aqueous space with uniform particle size. Formulation F4 composed of span 60 and cholesterol (1:1) gave the highest entrapment (93.26 ± 1.75%) and slower release results after 8 hours (Q8h = 60.35 ± 1.87%) among other formulations. The in-vitro drug permeation studies showed that there was a prolonged release of drug from niosomal gels as compared to niosomes itself. Considering the in-vitro drug release, niosomal gel formulation G2 was the best among the studied formulations. The release data were fitted to an empirical equation, which indicated that the release follows non-Fickian diffusion mechanism. The stability study revealed that incorporation of niosomes in gel increased their stability than the niosome itself. No signs of redness, inflammation, swelling or increased tear production were observed over the study period for tested formulation by Draize’s test. The intraocular pressure (IOP) lowering activity of G2 formulation showed relative bioavailability 2.64 times more than bioavailability of marketed Pilopine HS® gel. These results suggest that the niosomal gels containing pilocarpine HCl are promising ocular carriers for glaucoma treatment.

Objective: Pilocarpine hydrochloride is a direct acting cholinergic parasympathomimetic agent which directly stimulates cholinergic receptor (M3). It is a drug used in the treatment of chronic open-angle glaucoma for over 100 years. Designing a new ophthalmic dosage form for pilocarpine hydrochloride compels performing preformulation studies for drug. Therefore, the current aim of the study was to investigate some of the important physicochemical properties of pilocarpine hydrochloride which can help to select subsequent approaches during the development of niosomal gel for ocular use. Methods: Preformulation studies of drug were carried out for identification (physical appearance, melting point, and UV spectrophotometric analysis), solubility profile, lipophilicity (partition coefficient), compatibility studies by Fourier-transform infrared (FTIR) spectroscopy, and thermal behavior by differential scanning calorimetry (DSC). Results: The melting point of pilocarpine hydrochloride was found to be 204 ± 3○C. The log P value was found to be 1.12 ± 0.02, from which it can be interpreted that drug is highly hydrophilic in nature. The scanned λmax was found to be 215 nm. No significant changes were found when FTIR spectra of physical mixture compared with FTIR spectra of pure drug and excipients. This indicates absence of any possible interaction between the drug and excipients which confirms the identity and purity of drug. DSC thermogram of pure drug showed a sharp exothermic peak at 191.923○C (area=68.890 mJ, delta H = 22.963 J/g), indicating the crystal melting point of the drug. Conclusion: These results suggest that the pilocarpine hydrochloride serves as suitable candidate for ocular drug delivery system.

Interpenetrating polymer network (IPN) based drug delivery system is basically designed to deliver drugs at a predetermined rate for a desired period of time with minimum fluctuation. Due to its physical and biological characteristics such as enhanced solubility of hydrophobic drugs, excellent swelling capacity, imparting drug stability in the formulations, biodegradability, biocompatibility, weak antigenecity and targeting of drug in a specific tissue make it suitable for drug delivery as well as biomedical applications. IPN based drug delivery is primarily used for controlled release of drugs. These systems are also used for tissue engineering such as cartilage scaffolds, bone substitutes etc. The purpose of this review article is to cover recent advances on IPN based on its utilization as drug delivery matrix system for pharmaceutical applications as well as in tissue engineering for biomedical applications. Consequently, IPN is regarded as one of the most valuable novel biomaterials.