TOPICAL VERSUS INTRAVENOUS ADMINISTRATION OF TRANEXAMIC ACID - A COMPARISON OF INTRAOCULAR AND SERUM CONCENTRATIONS IN THE RABBIT

Background: Tranexamic acid has been shown to greatly reduce the incid ence of secondary hemorrhage when administered orally or intravenously . Topical administration of the drug should result in much lower serum concentrations, with fewer adverse effects, We performed a study to d etermine whether topical application of tranexamic acid would yield hi gher intraocular concentrations and lower serum concentrations of drug than intravenous administration. Methods: Ten New Zealand white rabbi ts received 25 mg/kg of tranexamic acid intravenously every 8 hours fo r 3 days. Another group of IO rabbits received one drop (0.05 mt) of c ommercially available tranexamic acid solution (100 mg/mL) every 8 hou rs for 3 days to one eye. Tranexamic acid levels in the aqueous humour , vitreous humour and serum I hour after administration of the last do se of drug were determined. Results: Analysis of variance showed that aqueous concentrations of tranexamic acid were significantly higher wi th topical delivery than with intravenous administration (15 vs. 9 mu g/mL) (p < 0.05). Serum concentrations were significantly lower follow ing topical administration (9 vs. 19 mu g/ml) (p < 0.01). The drug was not detected in the vitreous humour in either group. Interpretation: Topical delivery of tranexamic acid may prove to be valuable in yieldi ng therapeutic intraocular concentrations of drug in patients with hyp hema while minimizing systemic toxicity.