Formulation and evaluation of some selected timolol maleate ophthalmic preparations

ABSTRACT

The purpose of this study was to prepare and evaluate certain Timolol maleate [TM] polymeric formulations including viscous solutions, hydrogels and in-situ gels aiming to improve its ocular bioavailability and decrease its side effects. In this study, Chitosan [CS], hydroxyehtylcellulose [HEC], hydroxypropylmethylcellulose [HPMC] and sodium carboxymethylcellulose [NaCMC] were used to prepare TM viscous solutions and hydrogels. In-situ gels of Gelrite and Pluronic F-127 [Pl F-127] were prepared at different concentrations. Mucoadhesives namely CS or HEC were incorporated to Pl F-127 to produce mucoadhesive/insitu gel. The prepared formulations were evaluated for their in-vitro drug release, viscosity, gelation temperature and mucoadhesive force. The selected TM formulations were tested for their effect on intraocular pressure [IOP] and systemic side effects based on blood pressure [BP], heart rate [HR] and respiration rate [RR]. The results revealed that, TM in situ-gels F25 [containing Pl F-127 20% and CS 1.5% w/w] and F31[containing Gelrite 0.6% w/w] showed reasonable in-vitro results, and a marked IOP lowering activity without systemic side effects compared to TM marketed eye drops