Formulation and In vitro Evaluation of Loratadine Gels for Ophthalmic Use

Background: Loratadine is an oral H 1 antihistaminic drug which exhibits poor water solubility and very low dissolution rate. Objectives: An attempt was made in the current research study to prepare loratadine as ophthalmic gels for the treatment of ocular allergic conjunctivitis. Method: Loratadine ophthalmic gels were prepared using different polymers in various proportions and combinations. The solubility study, partition coefficient, drug content, viscosity and pH of the prepared formulations as well as the release characteristics of the drug in phosphate buffer solution having pH 7.4 were measured and its release kinetics was analyzed. Results: The solubility of loratadine increased linearly as a function of b-cyclodextrin (b-CyD) concentration. Gels containing loratadine-b-CyD complex had lower viscosity relative to gels containing free drug only. The pH values of the prepared gel formulations were within the acceptable range. Loratadine released from gel formulations containing its complex in a percentage higher than that released from gel formulations containing free drug only. This indicates a higher solubilizing effect of b-CyD. Conclusion: The obtained results encouraged a further In vivo study to investigate the efficacy of loratadine in these gel formulations for the treatment of ocular allergic conjunctivitis.