Drug Watch International

MARIJUANA RESEARCH REVIEW               

Dangerous side effects of cocaine are amplified when used in conjunction with marijuana

Drug-using volunteers were used in a study to determine the effect that marijuana smoking had on their subsequent use of cocaine. Lukas and colleagues (Pharmacol­ogy, Biochemistry and Behavior, Vol. 48:715-721,1994). The study found that the increase in heart rate due to cocaine was markedly enhanced if preceded by smoking marijuana, and that the time to the cocaine high was reduced from two minutes to one minute. Most importantly there was double the amount of drug absorption evident when marijuana use preceded cocaine use.

Commentary: Many drug users use two or more drugs at the same time. In analyses of poly-drug use, marijuana is the most heavily used illicit drug. Because it enhances the cocaine experience, it is commonly used in combination with this drug.

People snorting cocaine after smoking marijuana are at greater risk of overdose and more severe cardiovascular effects from the cocaine. Variability in the nasal effects of both drugs makes dosing unpredictable and dangerous. ##

Study on use of THC to treat HIV-wasting syndrome shows no weight gain.

A review of the current treatment for the HIV-wasting syndrome reported on studies with dronabinol, which has an approved use for anorexia in AIDS patients. Schroeder,

Hart, and Lynch (Annals of Pharmaco­therapy, Vol. 28:595-597, 1993). Dronabinol, a synthetic form of THC, the active ingredient in marijuana, was approved by the FDA based on a double-blind placebo-controlled clinical trial involving 139 AIDS patients in 18 centers.

Patients with a five-pound weight loss, no active infection, and no marijuana use for 30 days were included in the study. Dronabinol was given in a dose of 2.5 mg orally twice a day to the treatment group with a placebo control group. Patients reported an increase in appetite after six weeks of therapy. However, there was less than a half-pound weight gain in treated patients which was not statistically different from the one-pound weight loss in the placebo group at the end of the six week period.  

The authors conclude that the efficacy of dronabinol in reversing the wasting process associated with AIDS is yet to be determined, and that the subjective increase in appetite did not necessarily correspond to increased body weight.

Commentary: AIDS wasting is a devastat­ing complication of infection with the AIDS virus. The drug megestrol has been recently approved by the FDA and is far more effective than dronabinol in the studies to date.

Likewise,  no scientific studies have confirmed a benefit of the use of crude marijuana on HIV-wasting syndrome. Additionally, for the AIDS patient, smoking a substance with fungal and bacterial contamination, as well as the inherent damage by the smoke to lungs already predisposed to infection, would be counter­productive. ##

Review of anti-nausea drugs show restricted use for synthetic cannabinoids

Grunder and Hesketh (New England Journal of Medicine, Vol.329:1790-1795, 1993) recently reviewed current therapies for chemotherapy-induced vomiting control. The authors discuss the vomiting response and the neural pathways involved in mediating that response. Regarding the use of cannabinoids, the authors state that dronabinol and nabilone, the two cannabinoids that have been evaluated most thoroughly, are active only in patients receiving mild, not severely, emetogenic chemotherapy.  

The authors state that these drugs have serious side effects, however, including dysphoria, vertigo, hallucinations, sedation, and disorientation, and are seldom selected as first-line anti-emetic therapy. They point out that while these drugs have limited usage, some synthetic cannabinoids with no psychotropic activity have anti-emetic properties, suggesting that there are separate sites of action for the anti-vomiting and the psychotropic activity.  

Commentary: With the availability of newer anti-emetic drugs which are more potent, more effective and have less side effects in reversing nausea and vomiting associated with chemotherapy, the use of drugs with major side effects should be avoided.

One common assumption about taking anti-emetics orally is that the patients are already vomiting and cannot keep the medication down. However, all anti-emetic therapy is given prior to administration of chemotherapy drugs, before the onset of nausea and vomiting. Further, if the need for additional anti-emetic medication were indicated it could be administered in suppository form. ##

Study looks at immunologic impact of tobacco and marijuana smoke on the lungs

Wallace and associates, in Chest, Vol. 105:847-852, studied the effect of heavy, habitual marijuana use and compared it with tobacco smoking on the composition of cells in the peripheral blood and small airways of the lung.

Cell samples from 14 non-smokers were compared to samples from 14 tobacco smokers, 19 heavy habitual marijuana smokers, and 9 patients who smoked both substances. The tobacco smokers had lower percentages of cells in their small airways that had the marker for the CD4 or helper T-cells. Marijuana use had the opposite effect of lowering the CD8 positive cells, so-called suppressor cells, at the expense of CD4 cells. The authors concluded that tobacco and marijuana have effects on immune cells and blood lymphocyte populations that differ from each other, both in type and magnitude.

Commentary: These data are further examples of information from the group of Tashkin et al which show the effects of tobacco and marijuana smoke on the intrinsic cells in the lung and the immunologic defenses of the lungs. A combination of tobacco and marijuana would be devastating in terms of exposure of patients to carcino­gens, and also in damaging the immune response to foreign particles, bacteria, and viruses. Immunologic alterations that were observed in the study were of potential importance because they correlated with the adverse health effects of smoking either substance, alone or in combination. ##

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Material used in this publication has been has been reviewed and commented on by William M. Bennett, M.D., Professor, Chief of Nephrology, Clinical Pharmacology and Hypertension at Oregon Health Sciences University, Portland, Oregon.

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