tetrandrine

Tetrandrine is a naturally occurring bisbenzylisoquinoline alkaloid isolated from the roots of Stephania tetrandra, a plant in the Menispermaceae family used in traditional Chinese medicine as Fang Ji. It is one of several isoquinoline alkaloids produced by Stephania species.

Pharmacology and effects: Tetrandrine acts as a non-dihydropyridine calcium channel blocker, inhibiting L-type voltage-gated calcium channels and producing vascular relaxation in model systems. It has been reported to modulate immune responses and exhibit anti-inflammatory and antifibrotic activities in preclinical studies. The compound also inhibits P-glycoprotein, a drug efflux transporter, which can influence the intracellular concentration of co-administered chemotherapeutic agents and has been explored for reversal of multidrug resistance in cancer models. In vitro and in vivo studies have shown cytotoxic effects against various cancer cell lines, though clinical evidence remains limited.

Clinical status and research: Tetrandrine has been investigated primarily in preclinical and early-phase settings for cancer therapy, pulmonary and liver fibrosis, and inflammatory conditions. It is not approved as a standard treatment in most regulatory systems, and its use is largely restricted to research contexts and traditional medicine preparations. Potential safety concerns include hepatotoxicity, nephrotoxicity, and cardiotoxic risks, highlighting the need for careful dosing and monitoring.

Pharmacokinetics and safety considerations: The compound shows limited oral bioavailability and undergoes hepatic metabolism, with possible interactions involving cytochrome P450 enzymes and drug transporters. Caution is advised in patients with liver disease or those taking other medications that affect calcium channels or transporter activity. Adverse effects reported in studies include hypotension, bradycardia, and organ toxicity in susceptible individuals.