Aqueous humor and serum penetration of tacrolimus after topical and oral administration in rats: an absorption study

PURPOSE To investigate the penetration of tacrolimus to the aqueous and serum after topical and oral administration. METHODS Thirty Wistar rats were divided into three groups. In the first group (n = 12), a single dose of 0.3 % isotonic tacrolimus solution was applied topically to the rat eyes. The second group (n = 12), received 0.1 mg/kg/day tacrolimus for three days. In control group (n = 6), the rats were administered a single drop of 0.3% salin solution topically. Following collection of samples, the amounts of tacrolimus in aqueous and serum samples were compared with each other. RESULTS In group I, the mean concentration of tacrolimus was 35.16 ng/ml in aqueous and 2.22 ng/ml in serum. In group II, the mean concentration of tacrolimus was 13.08 ng/ml in aqueous and 13.45 ng/ml in serum. There was no significant difference in the serum concentration levels of tacrolimus between group I and control group. However there was a significant difference of the drug concentrations in aqueous between the groups (p < 0.001). The mean aqueous and serum concentrations of tacrolimus in group II, differed significantly from the mean concentrations in group I (p < 0.001) and the control group (p < 0.001). CONCLUSION Tacrolimus may be a promising treatment modality in intraocular inflammation by topical application besides systemic administration.