Emetina

Emetina, also spelled emetine, is a naturally occurring isoquinoline alkaloid derived from the root of the ipecacuanha plant (Cephaelis ipecacuanha). It is the principal active constituent of ipecac syrup, a traditional emetic, with cephaeline present in smaller amounts. Emetine has also been used for its anti-protozoal properties.

Historically, emetine was employed both to induce vomiting in poisonings and as a treatment for amoebic infections, particularly Entamoeba histolytica. In modern medicine, its use as an antiamoebic agent is limited due to safety concerns, and metronidazole or tinidazole followed by luminal agents are preferred for amoebiasis. Emetine remains of interest mainly in historical or specialized contexts.

Mechanistically, emetine inhibits protein synthesis by binding to the eukaryotic ribosome and blocking translocation, a action that disrupts parasite growth and host cell function at higher doses. Its antiamoebic effects are a consequence of this inhibition, though the compound also exhibits cytotoxic effects in humans, contributing to its narrow therapeutic window.

Safety and regulatory considerations are central to emetine’s profile. It is associated with significant toxicities, including cardiotoxicity (myocarditis, arrhythmias), neuromuscular weakness, and hepatotoxicity, and its therapeutic use requires careful dosing and monitoring. Because of these risks, emetine is rarely used today and is generally restricted to controlled clinical settings where alternatives are limited.

Current practice views emetine as largely of historical or limited, specialized use. Safer antiparasitic regimens have largely supplanted it, and products containing ipecac for home poisoning management are no longer routinely recommended due to safety concerns.