OCULAR TOLERANCE AND IN-VITRO RELEASE OF CHLORAMPHENICOL IN PROSPECTIVE EYE OINTMENT BASES
Objective: Chloramphenicol is poorly released from official eye ointment (EO) base. This study investigated alternative promising bases, enhanced drug release with surfactant and evaluated ocular tolerance of prototypes.
Methods: Chloramphenicol eye ointment (1 %w/w) was prepared by levigation in five bases: EO, simple ointment (SO), hydrous wool fat (HW), hydrous sheabutter (HS), and neat sheabutter (NS). In-vitro drug release of these and EO and SO formulations containing graded concentrations (0.1â€“10.0 %w/v) of surfactant (polysorbate 80 or propylene glycol) were studied over 3 h by dialysis technique, and the release kinetics assessed. Water-absorption capacity (WAC) and melting temperature of the bases was determined for probable influence on drug release. Ocular tolerance of the formulations, bases and surfactants was evaluated by in vivo irritancy test on albino rabbits.
Results: Total drug released from test formulations differed with base used: NS 12, HS 11, SO 7, HW 5, and EO 4 %. The Higuchi release kinetics was determined. HS and NS demonstrated highest release extent and rate; EO and HW exhibited poor release. WAC and softening temperature of bases showed some correlation with drug release propensity. Propylene glycol in EO and polysorbate 80 in SO formulations showed 3-fold and 2-fold enhanced drug release, respectively. All items for ocular toxicity test gave scores indicating practically no irritation, except neat HW that was mildly irritant.
Conclusion: HS and NS proved best alternatives to EO. Propylene glycol (10 %) in the EO formulation was 3-fold drug-release enhanced. All prototype formulations were non-irritant to eye tissue.
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