In Situ Gels Research Articles

Insitu gelling system : A Review

The purpose of writing this review on insitu gel was to complete the recent literature with special focus on insitu gelling system to increase the residence time of drug at the target site. Insitu gells are of particular interest for drugs that have very less half life and are readily dissolved. Recent developments of insitu gelling system is its use as vehicles for the delivery of drugs for both local treatment and systemic effects. The main interest in recent development of insitu gelling system has been shown in advantages of insitu polymeric delivery system such as ease of administration , reduced frequency of administration , improved patient compliance and comfort. This review summerises the studies to evaluate the performance and application of these systems. This review article is prepaired to discuss formulation factors used during development of insitu drug delivery system, relevant biodegrable polymers for sol-gel transition , characterization, evaluation parameter and commercial formulations of insitu polymeric system. Â

In vitro and in vivo studies on ocular vitamin A palmitate cationic liposomal in situ gels

N-trimethyl chitosan (TMC) with different degree of quaternization (DQ) as the coating materials, vitamin A palmitate (VAP)-loaded cationic liposomes dispersed in thermo-sensitive in situ gels (ISG) with poloxamer 407 (P407) as the base were prepared in this study. VAP-loaded liposomes (VAPL) were prepared using a film dispersion method followed by TMC-coating with DQ of 20%, 40% and 60% (TMC20, TMC40 and TMC60), respectively, then dispersed in P407 solution to obtain TMC-coated VAPL ISG. The in vitro properties of the system including morphology, size, zeta potential, entrapment efficiency, drug release and ocular retention were investigated. The ocular retention in vivo, eye irritation and pharmacokinetics in aqueous humor of the system were also studied in rabbits. VAPL revealed a spherical surface with mean size below 100 nm and negative zeta potential. After TMC-coating, the morphology and entrapment efficiency showed no significant changes, while the mean size was increased, zeta potential was changed into positive, and drug release was further sustained, and above all was influenced by DQ of TMC. TMC-coated VAPL exhibited little effect on the gelation temperature of P407 solution, and at the P407 concentration of 25% (w/v), TMC-coated VAPL ISG had the gelation temperature closest to the eye surface (34 °C) after diluted by the artificial tears. Compared with uncoated VAPL ISG and the marketed Oculotect gels, TMC-coated VAPL ISG displayed more retarded drug release and gel corrosion with a good linear relationship between them, and the higher DQ was, the slower drug release and gel corrosion. The ocular retention time in vitro and in vivo of TMC-coated VAPL ISG were both notable prolonged with a positive correlation with DQ of TMC. Compared with the marketed gels, TMC60-coated VAPL ISG showed delayed Tmax, improved Cmax and AUC(0–24) in rabbit aqueous humor, suggesting the sustained drug release and better corneal penetration and absorption. The local irritation of TMC-coated VAPL ISG was proved to be negligible. TMC-coated VAPL ISG with the properties of sustained drug release, prolonged ocular retention, improved corneal penetration and promising bio-safety is valuable to be studied further.

In-Situ Gelling System based on Thiolated Gellan Gum as New Carrier for Nasal Administration of Dimenhydrinate

The purpose of the present study was to develop intranasal delivery system of dimenhydrinate using thiolated gellan gum and formulations were modulated so as to have gelation at physiological ion content after intranasal administration. Gelation was determined by physical appearance. The mucoadhesive force in terms of detachment stress, determined using sheep nasal mucosa, increased with increasing concentration of thiolated polymer. The results of in vitro drug permeation studies across sheep nasal mucosa indicate that effective permeation could be significantly increased by using in situ gelling formulation with thiolated polymer concentration. Finally, histopathological examination did not detect any changes during in vitro permeation studies. In conclusion the gel formulation of dimenhydrinate with in situ gelling and mucoadhesive properties with increased permeation rate is promising for prolonging nasal residence time and thereby nasal absorption.