Pharmacokinetic parameters of ondansetron in rats after oral solution and transdermal invasomes gel: A comparison study

This study aimed to attain a comparison in pharmacokinetic parameters of ondansetron after transdermal (as invasomes gel) and oral (as solution) routes. Ondansetron is a 5 ‐ hydroxytryptamine receptor antagonist used for chemotherapy and radiotherapy ‐ induced nausea and emesis. The study was performed using Wistar albino rats weighing 200 ±20 g divided into two groups (6 of each). A dose of 0.28 mg of ondansetron, equivalent to 140 µl, was administered as an oral solution for the first group. Ondansetron-loaded invasomes gel was prepared, optimized, and applied on rat skin at a dose of 0.1652 mg of ondansetron, equivalent to 41 mg weight of invasomes gel for the second group. In addition, ondansetron was determined in rat plasma using HPLC apparatus and applying a modified HPLC method after validation. A comparison of primary pharmacokinetic parameters for both routes was performed. Results showed that C max , T max , AUC 0-24, and AUC 0-∞ were 58±3.4 ng/ml, 2±0.2 h., 246.25±47.6 ng.h./ml, and 259.4±57.7, respectively, for oral solution and 36±2.9 ng/ml, 5±0.5 h., 390.5±5.2 ng.h./ml and 442.8±66.1 ng.h./ml., respectively for transdermal invasomes gel. Results showed that the time and concentration needed to achieve the maximum effect (C max and T max ) were significantly different between oral and transdermal routes ( p <0.05). The relative bioavailability for the transdermal route was 2.9 times that of the oral route after a single dose administered for 24 h. In conclusion, the prepared invasomes gel enhanced the bioavailability of ondansetron, and transdermal delivery could be considered a vital delivery system for ondansetron.