Examining the debate on the use of medical marijuana.

The opium poppy and the coca leaf offer useful perspectives on the current controversies over medical marijuana. In both cases, purified synthetic analogues of biologically active components of ancient folk remedies have become medical mainstays without undermining efforts to reduce nonmedical drug use. A decade ago, a campaign strove to legalize heroin for the compassionate treatment of pain in terminally ill patients. Like the current campaign to legalize medical marijuana, many well-meaning people supported this effort. The campaign for medical heroin was stopped by science when double-blind studies showed that heroin offered no benefits over the standard opioid analgesics in the treatment of severe cancer pain. Scientific medicine requires purified chemicals in carefully controlled doses without contaminating toxic substances. That a doctor would one day write a prescription for leaves to be burned is unimaginable. The Controlled Substances Act and international treaties limit the use of abused drugs or medicines. In contrast to smoked marijuana, specific chemicals in marijuana or, more likely, synthetic analogues, may prove to be of benefit to some patients with specific illnesses. Most opponents of medical use of smoked marijuana are not hostile to the medical use of purified synthetic analogues or even synthetic tetrahydrocannabinol (THC), which has been available in the United States for prescription by any licensed doctor since 1985. In contrast, most supporters of smoked marijuana are hostile to the use of purified chemicals from marijuana, insisting that only smoked marijuana leaves be used as "medicine," revealing clearly that their motivation is not scientific medicine but the back door legalization of marijuana.