Coca leaf - Critical review report

Executive summary

This report synthesizes current scientific evidence on the chemistry, pharmacology, toxicology, traditional/therapeutic applications, and epidemiology of use of coca leaf in response to a Member State request for a critical review by the 48th Expert Committee on Drug Dependence.

Coca leaf is currently listed under Schedule I of the 1961 Single Convention (substances whose liability to abuse constitutes an especially serious risk to public health and which have very limited, if any, therapeutic usefulness).

Coca leaf refers to the unprocessed leaf of the coca bush, excluding those from which cocaine and related alkaloids have been removed. Four primary cultivated varieties are reviewed: E. coca var. coca, E. coca var. ipadu, E. novogranatense var. novogranatense, and E. novogranatense var. truxillense. Cocaine content varies across species and regions, ranging from 0.11% to 1.02% (dry weight).

The alkaloid cocaine can be extracted from the coca leaf using several solvents without altering its molecular structure. The simplicity and profitability of extraction contribute to its role in illicit cocaine production. One hectare of coca yields approximately 0.9 kg of cocaine hydrochloride annually.

Coca leaf contains a complex mixture of alkaloids, flavonoids, terpenes, and phenols. Its pharmacological effects include:

• Stimulant activity via inhibition of dopamine and norepinephrine reuptake.
• Antihypertensive and vasodilatory effects observed in several Erythroxylum species.
• Antioxidant, anti-inflammatory, and antimicrobial properties, with preclinical evidence supporting potential therapeutic applications.
• Hepatoprotective, antidiabetic, and anorectic effects, with limited human data.

Coca leaf exhibits low acute toxicity in animal models. No fatal overdoses have been reported from traditional use. Adverse effects are primarily localized (e.g., oral mucosa irritation) and dose-dependent. Coca leaf use is not associated with significant dependence or abuse potential in limited ethnographic studies, though high-dose extracts may mimic cocaine-like effects in animal models.

Traditional use in Andean regions includes coca leaf chewing and infusion (coca tea) for energy, altitude sickness, and digestive health. Studies suggest coca leaf may modulate glucose metabolism, improve exercise tolerance, and support nutritional intake, though clinical evidence remains limited.