Cooper also noted that swallowing a pill might be a safer way to take the drug than smoking it. There's some concern, though scant evidence, that smoking marijuana might increase the risk for lung cancer.
Dr. Gary Reisfield, an assistant professor of addiction medicine and chief of pain management services at the University of Florida College of Medicine, in Gainesville, praised the study for being "well-conceived and meticulously designed."
He said the research should help doctors and patients better understand how to use the drug.
"Smoked cannabis works faster, but oral THC works longer. For the management of chronic pain and other symptoms, the duration of action is often more important than the rapidity of onset. It is more convenient, and often more desirable, to administer a medication two or three times daily rather [than] every two or three hours," said Reisfield, who was not involved in the research.
When it comes to price, it costs somewhat more to swallow average doses of the drug than to smoke it, according to ProCon.org. At an average dose of two joints a day, it costs about $514 a month to smoke marijuana. The usual dose of dronabinol, which is the generic form of the drug Marinol, costs about $678 a month.
But dronabinol is often covered by insurance, so an insured patient would pay far less, between $15 and $30 each month for their prescription.
The study was published April 22 in the journal Neuropsychopharmacology.
For more on marijuana, visit the U.S. National Institute on Drug Abuse.
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