The study was conducted by researchers at Columbia University in New York and was published in the journal Neuropsychopharmacology.
The pill, known as Dronabinol, contains the active ingredient of marijuana - tetrahydrocannabinol (THC) - and has already been approved to treat chemotherapy and AIDS patients with nausea and vomiting.
The scientists said:
"Recent studies have demonstrated the therapeutic potential of cannabinoids to treat pain, yet none have compared the analgesic effectiveness of smoked marijuana to orally administered tetrahydrocannabinol (THC; dronabinol)."
The study involved 30 participants (15 male and 15 female) who were marijuana smokers. The researchers, led by Ziva Cooper and Margaret Haney, set out to compare subjects' daily pain response.
The volunteers were asked either to smoke marjuana, take oral Dronabinol, or a placebo. They then took part in an experiment called a "cold pressor test" where they immersed their hand into a bath of very cold water (4 degrees celsius) for up to two minutes.
How long it took them to report pain (pain sensitivity) and remove their hand from the water (pain tolerance) were documented.
Results showed that compared to placebo, marijuana and Dronabinol:
- lowered subjective ratings of pain
- reduced pain sensitivity
- increased pain tolerance
However, the experts in the current study found that the drug Dronabinol provided a longer-lasting effect in pain sensitivity and was less susceptible to abuse-associated outcomes, compared to marijuana.
"The magnitude of peak change in pain sensitivity and tolerance did not differ between marijuana and dronabinol, although dronabinol produced analgesia that was of a longer duration."
A previous study showed that an oral tablet of THC tended to make the experience of pain more bearable, instead of actually decreasing the intensity of the pain.
The authors pointed out that the report only observed people who had previously smoked marijuana on a daily basis. Therefore, Dronabinol's effects on non-smokers are still not known.
Although more research is necessary, the findings show potential for medical uses of the THC pill.