Piperine has also been found to inhibit human CYP3A4 and P-glycoprotein, enzymes important for the metabolism and transport of xenobiotics and metabolites.[2] In animal studies, piperine also inhibited other enzymes important in drug metabolism.[3][4] By inhibiting drug metabolism, piperine may increase the bioavailability of various compounds. Notably, piperine may enhance bioavailability of curcumin by 2000% in humans.[5]
In February 2008 researchers discovered that piperine can stimulate pigmentation in the skin.
The study, by King's CollegeLondon, appears in the British Journal of Dermatology.
Due to its effects on drug metabolism, piperine should be taken cautiously (if at all) by individuals taking other medications.
Allicin, the active piquant flavor chemical in uncooked garlic and onions (see those articles for discussion of other chemicals in them relating to pungency, and eye irritation)
^ Bhardwaj RK, Glaeser H, Becquemont L, Klotz U, Gupta SK, Fromm MF (2002) Piperine, a major constituent of black pepper, inhibits human P-glycoprotein and CYP3A4. J. Pharmacol. Exp. Ther.302(2):645-50. PMID 12130727
^ Atal CK, Dubey RK, Singh J (1985) Biochemical basis of enhanced drug bioavailability by piperine: evidence that piperine is a potent inhibitor of drug metabolism J. Pharmacol. Exp. Ther.232(1):258-62 PMID 3917507
^ Reen RK, Jamwal DS, Taneja SC, Koul JL, Dubey RK, Wiebel FJ, Singh J (1993) Impairment of UDP-glucose dehydrogenase and glucuronidation activities in liver and small intestine of rat and guinea pig in vitro by piperine. Biochem. Pharmacol.46(2):229-38 PMID 8347144
^ Shoba G, Joy D, Joseph T, Majeed M, Rajendran R, Srinivas PS (1998) Influence of piperine on the pharmacokinetics of curcumin in animals and human volunteers. Planta Med.64(4):353-6 PMID 9619120