Enhanced bioavailability of triprolidine from the transdermal TPX matrix system in rabbits

The pharmacokinetics and bioavailability of triprolidine, antihistamines, were studied to determine the feasibility of enhanced transdemal delivery of triprolidine from the poly(4-methyl-1-pentene) (TPX) matrix system containing polyoxyethylene-2-oleyl ether in rabbits. The triprolidine-TPX matrix (50 mg/kg) was applied to abdominal skin of rabbits. Blood samples were collected via femoral artery for 36 h and the plasma concentrations of triprolidine were determined by HPLC. Pharmacokinetic parameters was calculated using the LAGRAN computer program. The area under the curve (AUC) was significantly higher in the enhancer group (4058 +/- 1420 ng/ml h) than that (1902 +/- 857 ng/ml h) in control group (P<0.05), showing about 235% increased bioavailability. The average Cmax was increased significantly in the enhancer group (216 +/- 44.3 ng/ml) compared with control group (130 +/- 25.8 ng/ml) (P<0.05). The mean Tmax was increased in the enhancer group (8.0 +/- 2.55 h) compared with the control (6.0 +/- 2.28 h) but was not significant. The relative bioavailability was 23.1% in the control group and 49.3% in the enhancer group compared to the oral route. As the triprolidine-TPX matrix containing polyoxyethylene-2-oleyl ether as an enhancer and tiethyl citrate as a plasticizer was administered to rabbits via the transdermal routes, the relative bioavailability increased by about 2.13-fold compared to the control group, showing a relatively constant, sustained blood concentration with minimal fluctuation. The results of this study shows that triprolidine-TPX matrix could be developed as a transdermal delivery system providing consistent plasma concentration.