Effects of taraxacum mongolicum on the bioavailability and disposition of ciprofloxacin in rats.

Taraxacum mongolicum (TM), also known as dandelion, is a herb widely used in the East for its antibacterial activity. The high mineral content of TM presents a potential problem for the absorption of quinolone antibiotics. This study was undertaken to discern the significance of a drug-drug interaction between TM and ciprofloxacin. Two groups of Sprague Dawley rats (220-250 g) were employed; one received a single oral dose of ciprofloxacin (20 mg/kg) with concomitant oral administration of an aqueous TM extract (2 g crude drug/kg) while the control group received oral ciprofloxacin (20 mg/kg) only. Ciprofloxacin in plasma and urine, collected over 6 and 24 h, respectively, was determined by HPLC. Noncompartment analysis was employed for pharmacokinetic parameter estimation. Results indicated that, as compared to control, maximum plasma concentration (Cmax) of ciprofloxacin was significantly lowered by 73% in rats receiving concurrent TM dosing. Oral TM also caused a 3-fold increase in both apparent drug distribution volume (Vd,lambdaz/F: 92. 0 vs 30.8 L/kg) and terminal elimination half-life (t1/2,lambdaz; 5. 71 vs 1.96 h). Partly due to the changes in drug distribution and elimination, relative bioavailability of ciprofloxacin, as assessed by AUC0-->infinity, remained similar for both dosing groups. These findings suggest the possibility of a multifactorial drug-drug interaction between TM and ciprofloxacin. Thus, the implications of concomitant dosing of the two agents should not be overlooked.