BBSNews 2007-07-03 -- (MPP) WASHINGTON, D.C. -- Two just-published scientific studies provide further evidence that medical marijuana laws do not increase marijuana use, and that even weak marijuana works as well as (and in some ways better than) high-dose Marinol, the THC pill sometimes touted as a substitute for marijuana.

In a study published online by the International Journal of Drug Policy, researchers from the Texas A&M Health/Science Center analyzed two sets of data designed to monitor emerging drug-use trends, the Arrestee Drug Abuse Monitoring System (ADAM) and the Drug Abuse Warning Network (DAWN), from locations where medical marijuana laws have been put into effect. ADAM is based on urine tests of adult and juvenile arrestees, while DAWN tracks mentions of drug use in records of hospital emergency departments. Both sets of data, from before and after implementation of the medical marijuana laws, were looked at in a "time-series analysis" based on the premise that "if the law in question has an impact (either positive or negative) then the series of observations that follow its implementation will have a different slope or trend than those that occurred before."

In both sets of data -- from California, Colorado, Oregon, and Washington -- the researchers found no change in the trend after medical marijuana laws went into effect. "Consistent with other studies of the liberalization of cannabis laws," they wrote, "[the results] indicate that medical cannabis laws do not increase use of the drug."

A second study, in the Journal of Acquired Immune Deficiency Syndromes and also published online ahead of its appearance in print, compared the THC pill marketed as Marinol to smoked marijuana supplied by the National Institute on Drug Abuse. While both medications proved effective at stimulating appetite, reducing the need for other medications to combat gastrointestinal problems, and helping patients sleep, it took eight times the recommended dose of Marinol to roughly equal the efficacy of weak marijuana, with 3.9 percent THC, supplied by NIDA. According to the White House Office of National Drug Control Policy, the average THC content of marijuana seized by law enforcement during the first quarter of 2007 was 8.5 percent.

The study's "double-dummy" design successfully prevented patients from identifying which active treatment they were receiving at any given time, overcoming a common problem with marijuana and THC studies. Although researchers characterized the efficacy of Marinol and whole marijuana in the study as "similar," only whole marijuana produced statistically significant improvements in patients' levels of hunger, desire to eat, and quality of sleep. Marijuana also produced a higher daily caloric intake than even the highest Marinol dose, although in this small and relatively brief study, that difference did not reach statistical significance.

Neither treatment produced significant negative side effects. Strikingly, when patients were given a series of tests measuring learning, memory and other cognitive functions, neither marijuana nor oral THC produced any significant changes in performance.

Gorman DM and Huber J Charles Jr. Do Medical Cannabis Laws Encourage Cannabis Use? International Journal of Drug Policy, 2007 Vol. 18 no. 3, pp. 160-7.

Haney M, Gunderson EW, Rabkin J, Hart CL, Vosburg SK, Comer SD, and Foltin RW. Dronabinol and Marijuana in HIV-Positive Marijuana Smokers: Caloric Intake, Mood, and Sleep. J Acquir Immune Defic Syndr. 2007 Jun 21; [Epub ahead of print]