People who use the heart drug digitalis don’t need to fill their window boxes with the foxglove flowers from which it derives. They take a pill.
People with headaches are rarely seen gnawing the bark of willow trees, the original source of aspirin.
So why do people who derive medical benefits from marijuana have to smoke or eat the actual plant, whose potency can vary greatly? If marijuana contains therapeutic ingredients, why aren’t they available as prescription medicine?
There is, in fact, a “marijuana pill” called Marinol (dronabinol), tested for safety and efficacy and available by prescription since 1985. The pill contains a synthetic version of tetrahydrocannabinol, or THC, the main active ingredient in marijuana, and it has been approved to treat nausea and vomiting associated with chemotherapy.
But it apparently doesn’t work well enough for marijuana fans, because in pill form, the drug enters the bloodstream too slowly.
“Pills and inhalation by smoke are not equivalent methods of administration,” said Alvin K. Swonger, a retired professor of pharmacology and toxicity at the University of Rhode Island. “Pills take longer to get absorbed.” Additionally, dose per dose, street marijuana is cheaper than Marinol, he added.
Advocates of medical marijuana also point out that THC is not the only active ingredient in marijuana. Other chemicals in the plant — particularly cannibidiol, or CBD — may interact with THC to enhance its effectiveness. Also, advocates say, by smoking marijuana and feeling its almost immediate effects, patients can control their dosage.
But that method exposes people to carcinogenic effects of smoke, noted Swonger (who believes the risks of legalizing marijuana as medicine outweigh the benefits). “The lungs weren’t meant to be filter paper, to filter particulate matter out of smoke,” he said.
A British company, GW Pharmaceuticals, has developed a drug that contains both THC and CBD and is administered by spraying it into the mouth. The drug, called Sativex, has been approved in the United Kingdom for treatment of muscle stiffness caused by multiple sclerosis and in Canada for relief of certain types of pain. It has not been approved for use in the United States, but, according to the manufacturer’s website, it is being studied as a painkiller for patients with advanced cancer and persistent pain that has not responded to other treatments.
But there are many obstacles to developing drugs derived from marijuana. A 1999 Institute of Medicine report on the scientific evidence on marijuana listed the hurdles: difficulty obtaining enough legal, standardized marijuana for study; the “exacting requirements for FDA approval” of a new drug; the health risks of smoking; satisfying the requirements of the Controlled Substances Act; the cost of developing and testing the drug; and the fact that a plant cannot be patented.
The biggest obstacle, however, may be the movement toward medical marijuana in states like Rhode Island. Joel W. Hay, a professor of pharmaceutical economics and policy at the University of Southern California School of Pharmacy, believes “medical marijuana is just a smokescreen to get recreational marijuana used in a legal fashion.” Ironically, he said, that diminishes the chances for an approved, standardized drug derived from marijuana.
“The push by the drug legalizers to get medical marijuana into the tent,” he said, “makes it even less likely that any legitimate pharmaceutical research firm is going to go ahead and develop a legitimate, FDA-approved product.” Given the high cost of drug development, he said, “How can you compete against street marijuana?”
via : projo.com
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