Smoking marijuana provides analgesic effect on HIV neuropathy

A nine-day pilot study of 16 patients carried out by researchers at the University of California, San Francisco, found that smoking marjuana had an analgesic effect on HIV neuropathy.

Sixteen patients (14 men, median age 43) with previous experience of smoking marijuana, but who had not done so for 30 days prior to the study, and with an average of six years duration of neuropathy, were enrolled in the open-label, in-patient study. Neuropathy was related to HIV alone (3), nucleoside therapy (8) or both (5). After a two-day lead-in period, patients smoked one 3.56% THC containing joint three times a day for seven days. A heat capsaicin model induced experimental pain. Patients experiencing a greater than 30% reduction in their 24-hour neuropathy pain scored on a 0-100 visual analogue scale were assessed as responders.

The mean baseline average daily pain value was 47/100 but this dropped to 40/100 following the two-day lead-in. The smoking of marijuana caused a drop in mean pain score to 20/100, with 10/16 patients experiencing a greater than 30% reduction in average daily pain.

The researchers report: “Excellent correlation was seen in response to the heat capsaicin model where 14/16 patients experienced a greater than 30% reduction in the area of secondary hyperalgesia after smoking.”

In an attempt to confirm these preliminary results, the researchers have initiated a 50-subject, seven-day randomised placebo-controlled trial.

Jay C, Shade S, Vizoso H et al. The effect of smoked marijuana on chronic neuropathic and experimentally induced pain in HIV neuropathy: Results of an open-label pilot study. 11th CROI 2004, Abstract 496.