MDMA (ecstasy) strongly inhibits the liver enzyme CYP2D6, which is responsible for metabolizing many drugs. In a controlled trial with 15 healthy men, a single 1.5 mg/kg oral dose of MDMA increased blood levels of the probe drug dextromethorphan about tenfold and reduced its breakdown product dextrorphan. The urinary metabolic ratio rose nearly 100-fold, and two-thirds of participants temporarily showed a metabolic profile typical of poor metabolizers. CYP2D6 activity recovered after 10 days, with a half-life of 46.6 hours. Users should be warned that MDMA can dangerously alter the metabolism of other medications.
Since 2004, herbal smoking blends sold under the brand Spice drugs have been available online and in smart shops, advertised as aromatic incense not for human use. Users report effects similar to cannabis, and forensic analyses have identified potent synthetic cannabinoid agonists such as JWH-018, CP 47497, JWH-073, and HU-210 in these products. Very little data exist on their pharmacological properties in animals, and no information on their toxicity is available. Their pharmacology, toxicology, and safety in humans remain largely unknown, with only user reports from Internet forums. Neither the plant ingredients nor the identified cannabinoids are listed in the UN 1961 or 1971 controlled substance conventions. Some countries have recently taken legal action to prohibit or control these products.