processes, cachexia and starvation. Cachexia (pronounced kah-KEK-see-uh) results from tissue injury and causes a disproportionate loss of lean tissue mass, such as muscle or liver; the same process also occurs during the final stages of cancer. Starvation, by contrast, results from food or nutrient deprivation; it causes a loss of body fat before lean tissues become depleted. While starvation can be cured simply by eating, curing cachexia generally requires controlling the disease that triggered it and artificially stimulating the body 's metabolism.

Research indicates that people begin losing muscle and other lean tissues even before developing full-blown AIDS, possibly as a result of the body's response to viral infection. Later, opportunistic infections or ulcers of the mouth, throat, or esophagus make eating difficult. Other infectious organisms cause diarrhea, which reduces nutrient absorption, as does the overgrowth of microbes that naturally inhabit the digestive tract. Depression, fatigue, and poverty may further exacerbate malnutrition in AIDS patients.

Standard therapy for AIDS wasting focuses on stimulating the patient 's appetite, usually with the drug megestrol acetate (Megace). Although approved for this purpose, Marinol is prescribed far less often. Clinical studies indicate that Megace stimulates weight gain more effectively than Marinol and that patients get no additional benefit by using the drugs in combination.2 People who take Megace typically increase their food consumption by about 30 percent, but gain mostly fat, rather than lean tissue or muscle mass. Like Megace, Marinol reverses starvation but has no effect on cachexia. Presumably, the same is true of marijuana.

To date, THC is the only cannabinoid that has been evaluated in the clinic for its ability to stimulate appetite and thereby counteract AIDS wasting. In short-term (six weeks) and long-term (one year) studies, patients who received THC in the form of Marinol tended to experience increased appetite while maintaining a stable weight. 3 In addition, five patients in a preliminary study gained an average of 1 percent body fat after taking the drug for five weeks.4

Some patients in these and other studies have experienced unpleasant side effects from the drug, ranging from dry mouth to psychological distress. These problems are exacerbated by the dif-

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement