APA new study suggests that legalizing smoked marijuana for medical use isn't necessary — the active ingredient in marijuana, available in pill form, actually relieves pain longer than the smoked stuff.
The drug in question, introduced in 1985, is used to treat nausea and vomiting caused by chemotherapy, and loss of appetite cause by AIDS or anorexia nervosa. The generic name is dronabinol, and is sold as Marinol in the U.S.
It contains a lab-made version of Tetrahydrocannabinol (THC) the active ingredient in smoked marijuana. You need a prescription to get it.
The pill form takes longer to set in (about 45 minutes versus 15 for smoked marijuana), and its effects peak between two and four hours after taking a dose. The brain-related effects can last up to six hours, while the appetite stimulation effects can continue for a full day.
The latest study, published Monday, April 22 in the journal Neuropsychoparmacology, indicates that the pain-relieving effects of Marinol actually last longer than the pain-relief effects of smoked marijuana.
This is good news because smoking marijuana has more health risks than orally-administered marijuana in pill form: The smoke from the burning plant produces carcinogens, while higher levels of intoxication from smoking make driving dangerous.
In the new study, researchers compared the pain responses of 30 daily marijuana smokers when given a pill (either Marinol or a sugar pill) and given marijuana in smoked form (with varying levels of THC.
The patients didn't know how much of a THC dose they got or if it was the pill or the marijuana smoke through which they got it.
They were tested for their pain reaction by submerging their left hand in ice water until they couldn't handle it any more — the longer they held the hand in the water, the higher their pain tolerance was. The researchers also tested their intoxication levels and other effects of THC.
They found (from the paper's press summary) that:
The results show that compared to placebo, marijuana and dronabinol decreased pain sensitivity, increased pain tolerance, and decreased subjective ratings of pain. Compared to marijuana, dronabinol produced longer-lasting decreases in pain sensitivity and lower ratings of abuse-related subjective effects.
Previous studies have shown that the impact of Marinol isn't the same on all types of pain. It doesn't work well for post-operative pain or inflammatory pain. Also, the subjects in the test were chronic marijuana smokers, so non-smokers might react differently to the pill-versus-smoke test, the researchers warned.