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 i n the East for its antibacterial activity. The high mineral content of TM p resents a potential problem for the absorption of quinolone antibiotics. Th is study was undertaken to discern the significance of a drug-drug interact ion between TM and ciprofloxacin. Two groups of Sprague Dawley rats (220-25 0 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 cru de drug/kg) while the control group received oral ciprofloxacin (20 mg/kg) only. Ciprofloxacin in plasma and urine, collected over 6 and 24 h, respect ively, was determined by HPLC. Noncompartment analysis was employed for pha rmacokinetic parameter estimation. Results indicated that, as compared to c ontrol, maximum plasma concentration (C-max) of ciprofloxacin was significa ntly lowered by 73% in rats receiving concurrent TM dosing. Oral TM also ca used a 3-fold increase in both apparent drug:distribution volume (V-d,V-lam bda Z/F: 92.0 vs 30.8 L/kg) and terminal elimination half-life (t(1/2),(lam bda z); 5.71 vs 1.96 h). Partly due to the changes in drug distribution and elimination, relative bioavailability of ciprofloxacin, as assessed by AUC (0-infinity), remained similar for both dosing groups. These findings sugge st the possibility of a multifactorial drug-drug interaction between TM and ciprofloxacin. Thus, the implications of concomitant dosing of the two age nts should not be overlooked.