Short-term cannabis use does not adversely affect HIV viral load or CD4 and CD8 cell counts, according to a small US study published in the August 2003 edition of the Annals of Internal Medicine.
Cannabis is widely used by HIV-positive individuals, both as a recreational drug and an appetite stimulant to combat wasting. It is estimated that in the 1990s 11,000 HIV-positive individuals in San Francisco were members of a cannabis-buying club. The drug is nevertheless illegal in nearly all countries, and there are concerns that cannabis use could lead to an increase in HIV viral load and impaired immune function. Cannabis is metabolised by the body using the P-450 pathway, which is also utilised by protease inhibitors, and earlier studies have suggested that cannabis use has the potential to negatively impact on the immune system.
Investigators at the University of San Francisco recruited 62 HIV-positive individuals, taking a HAART regimen including the protease inhibitors indinavir or nelfinavir, and a stable HIV viral load to a 21 day double blind, three-arm, placebo controlled trial designed to assess the safety and toxicity of cannabis use.
Individuals were randomly assigned to receive pre-rolled cigarettes containing 3.95% delta-9-tetrahydrocannabinol, dronabinol tablets which contain cannabinoids, or a placebo. At baseline 58% of patients had an HIV viral load below 50 copies/mL and CD4 and CD8 cell counts were comparable across the three arms of the trial.
If an individual was taking 1250mg of nelfinavir twice daily, they were required to change to thrice daily dosing of 750mg. A condition of participating in the study was that participants remained in the University of San Francisco’s General Clinical Research Center for the duration of the trial. Individuals were not allowed to leave the facility or receive visitors unless a member of clinical staff accompanied them. Patients were provided their study medication under supervision an hour before meals, and any unsmoked cannabis was collected by investigators and returned to the pharmacy.
None of the patients who had an undetectable HIV viral load at baseline rebounded during the course of the study, and amongst individuals with a detectable viral load there were slight, but not significant falls in viral load in both the cannabis and dronabinol arms. CD4 and CD8 cell counts did not increase significantly in the placebo arm of the trial, but a 20% increase in both CD4 and CD8 cell count was observed in the dronabinol arm, and a 20% in CD8 cell count and 10% rise in CD4 cell count in the cannabis arm.
Neither levels of nelfinavir nor indinavir were adversely affected by either cannabis or dronabinol use.
Investigators also noted that patients in both of the medication arms of the trial experienced significant weight gain during the 21 days of the study, cannabis patients gaining an average of 3kg and dronabinol recipients 3.2 kg (p=0.021 and p=0.004 respectively). However, in both instances the weight gain was in fat rather than in lean muscle mass.
The investigators conclude that their study, “provides evidence that short-term use of cannabinoids, either oral or smoked, does not substantially elevate viral load in individuals with HIV infection who are receiving stable antiretroviral regimens containing nelfinavir or indivinavir.” Although the investigators are confident that the design of their study ensured that any harmful effects of cannabis would have been revealed, they caution that “the results of this study, which evaluated government-supplied marijuana of known potency and content, cannot be extrapolated to the potential effects of marijuana available on the streets.”
Further information on this website
Cannabis - factsheet
Abrams DI et al. Short-term effects of cannabinoids in patients with HIV-1 infection. Annals of Internal Medicine 139: 258 – 266, 2003.