Haritaki

Terminalia chebula (TCR) significantly inhibits CYP2C19, as demonstrated in an in vivo rat pharmacokinetic study. CYP2C19 is the primary enzyme responsible for metabolising proton pump inhibitors (omeprazole, esomeprazole, lansoprazole, pantoprazole). TCR inhibition reduces omeprazole plasma clearance, raising AUC and Cmax, potentially leading to supratherapeutic drug levels.

Monitor for signs of increased PPI effect (e.g., prolonged acid suppression, B12 deficiency with long-term use). Advise prescribers of haritaki use if adjusting PPI dosing. Separation of administration by at least 2 hours is prudent.

Clopidogrel is a prodrug requiring CYP2C19-mediated bioactivation to its active thiol metabolite. Terminalia chebula significantly inhibits CYP2C19 activity (decreased plasma clearance of omeprazole, a CYP2C19 probe, confirmed in rat pharmacokinetics). This inhibition could reduce clopidogrel bioactivation, potentially diminishing its antiplatelet effect and increasing cardiovascular risk.

Patients on clopidogrel for cardiovascular protection (post-stent, ACS) should avoid concurrent use of haritaki/Terminalia chebula preparations. If co-administration occurs, enhanced antiplatelet monitoring is essential. Discuss with treating cardiologist.

Terminalia chebula inhibits CYP2E1 in vivo (rat studies), reducing chlorzoxazone clearance, a CYP2E1 probe. CYP2E1 plays a key role in generating the hepatotoxic NAPQI metabolite of acetaminophen. Inhibition of CYP2E1 may decrease NAPQI formation, but haritaki tannins may also independently stress hepatic enzymes. The net hepatic interaction is uncertain.

Patients taking acetaminophen regularly (including OTC products) alongside haritaki should be monitored for liver function. Avoid concurrent use with high-dose or chronic acetaminophen, especially in patients with liver disease or those who consume alcohol.

Terminalia chebula has documented antidiabetic properties attributed to chebulinic acid, chebulagic acid, and gallic acid, which enhance insulin signalling, inhibit alpha-glucosidase, and improve glucose uptake. Concurrent use with antidiabetic drugs may produce additive hypoglycaemic effects.

Monitor blood glucose levels carefully when patients use haritaki alongside antidiabetic medications. Dose adjustment of the conventional antidiabetic may be necessary. Educate patients about hypoglycaemia warning signs.

Haritaki contains high levels of tannins (ellagitannins, chebulagic acid, gallic acid) which can form insoluble complexes with drug molecules, proteins, and minerals in the GI tract, substantially reducing their bioavailability and absorption. This effect is non-specific and may affect a broad range of orally administered medications.

Advise patients to take all prescription medications at least 2 hours before or 3 hours after haritaki preparations to minimise tannin-mediated binding and absorption reduction. This is particularly important for antibiotics, cardiac medications, thyroid hormones, and immunosuppressants.