Metabolism and Disposition of Tribendimidine and Its Metabolites in Healthy Chinese Volunteers

Background: Tribendimidine is a new anthelmintic agent synthesized by Chinese scientists. It is a broad spectrum agent with high activity against parasites. However, its disposition and metabolism remain unknown. Objective: To investigate the metabolism, disposition, and metabolites of tribendimidine in healthy human volunteers. Methods: Twelve healthy Chinese volunteers were chosen after clinical assessment of health status and laboratory tests. They received single oral doses of tribendimidine 400mg enteric-coated tablets. Blood and urine samples were collected at scheduled timepoints. Samples were qualitatively and quantitatively analyzed by liquid chromatography-mass spectrometric (LC-MS) and high performance liquid chromatography (HPLC) methods, respectively. Results: Tribendimidine was rapidly and completely broken down to p-(1-dimethylamino ethylimino) aniline (dADT) and terephthalaldehyde (TPAL). Furthermore, dADT was partially transformed to acetylated dADT, and TPAL completely transformed to terephalic acid (TPAC). The main pharmacokinetic parameters (± SD) of dADT were as follows: elimination half life (t(1/2)) 4.74 ± 1.80 h; elimination rate constant (K(e)) 0.16 ± 0.06 h(−1); apparent volume of distribution (Vd/F) 12.23 ± 8.69L • kg(−1); apparent total clearance of the drug from plasma (CL/F) 1.63 ± 0.58L • h(−1) • kg(−1); area under the plasma concentration-time curve (AUC) from time 0 to time 24 hours (AUC(24)) 4.29 ± 1.88 μg • mL(−1) • h; AUC from time zero to infinity (AUC(∞)) 4.45 ± 1.81 μg • mL(−1) • h; maximum plasma drug concentration (C(max)) 0.64 ± 0.27 μg • mL(−1); and time to C(max) (t(max)) 4.20 ± 0.71 h. A total of 35.28% dADT and 28.50% TPAC were excreted through the urine within 24 hours after tribendimidine administration. Conclusion: These results reveal the disposition, metabolism, and main metabolites of tribendimidine in healthy Chinese volunteers.