Effect of piperine, a major component of black pepper, on the pharmacokinetics of domperidone in rats.

The present study was aimed to investigate the effect of piperine, a major active ingredient of black pepper, on the pharmacokinetics of domperidone in rats. Animals were given oral (p.o.) or intraperitoneal (i.p.) domperidone (20 mg/kg) alone or together with piperine (20 mg/kg, p.o.). Plasma samples were collected at 0.25, 0.5, 1.0, 2.0, 3.0, 4.0, 6.0, 8.0, 10.0 and 12 hours after drug administration. The concentration of domperidone in the plasma was measured using a HPLC method. The concomitant administration of piperine with oral or intraperitoneal domperidone resulted in a significant (P<0.05) increase in the maximum plasma concentration (Cmax), the mean area under the plasma concentration-time curve (AUC), and the elimination half-life (t1/2) of domperidone as compared to those obtained for domperidone alone. These results suggest that an important pharmacokinetic interaction may occur if piperine is administered concurrently with domperidone.

The analgesic and anticonvulsant effects of piperine in mice.

Piperine, is the major active principal of black pepper. In traditional medicine, black pepper has been used as an analgesic, anti-inflammatory agent and in the treatment of epilepsy. This study was conducted to evaluate the in vivo analgesic and anticonvulsant effects of piperine in mice. The analgesic and anticonvulsant effects of piperine were studied in mice using acetic acid-induced writhing, tail flick assay, pentylenetetrazole (PTZ)- and picrotoxin (PIC)-induced seizures models. The intraperitoneal (i.p.) administration of piperine (30, 50 and 70 mg/kg) significantly inhibited (P<0.01) the acetic acid-induced writhing in mice, similar to the effect of indomethacin (20 mg/kg i.p.). In the tail flick assay, piperine (30 and 50 mg/kg, i.p.) and morphine (5 mg/kg, i.p.) caused a significant increase (P<0.01) in the reaction time of mice. Pre-treatment of animals with naloxone (5 mg/kg i.p.), reversed the analgesic effects of both piperine and morphine in the tail flick assay. Piperine (30, 50 and 70 mg/kg, i.p.) and standard drugs, valproic acid (200 mg/kg, i.p.), carbamazepine (30 mg/kg, i.p.) and diazepam (1 mg/kg, i.p.) significantly (P<0.01) delayed the onset of PTZ-and PIC-induced seizures in mice. These findings indicate that piperine exhibits analgesic and anticonvulsant effects possibly mediated via opioid and GABA-ergic pathways respectively. Moreover, piperine being the main constituent of black pepper, may be contributing factor in the medicinal uses of black pepper in pain and epilepsy.