Preliminary I n V ivo Safety Evaluation of a Tacrolimus Eye Drop Formulation Using Hydroxypropyl Beta Cyclodextrin After Ocular Administration in NZW Rabbits

Tacrolimus is an immunosuppressive drug with higher potency compared to cyclosporine A (as a useful immunosuppressant). We prepared an ophthalmic solution formulation of Tacrolimus using hydroxypropyl beta cyclodextrin (HP-ßCD). In the present study, safety of this formulation was investigated in rabbits. Formulation containing HP-ßCD, Tacrolimus, Polyvinyl alcohol (PVA) and Benzalkonium Chloride in PBS 7.4 was prepared. Tacrolimus concentration in ophthalmic preparation was 0.05% w/v. Ten male New Zealand white rabbits were housed in clean separated cages. One drop of Tacrolimus prepared formulation and a placebo formulation were applied every 12 hrs in the right and left eyes respectively, for 28 days. This new aqueous formulation of Tacrolimus could improve Tacrolimus solubility about 42 times. Clinical examinations on the 1st, 3rd, 7th, 14th and 28th days of study showed transient redness and conjunctivitis in some cases of both control and intervention groups that was not persistent. At the end of the study, there were no statistical differences between the two groups in corneal epithelial defect, redness or pathological evaluations. The results of this study suggest that eye drop formulation of CD-Tacrolimus is safe in preliminary evaluations and can be useful for further studies.