Objective To evaluate the effect of the oral synthetic
_-9-tetrahydrocannabinol dronabinol on central neuropathic
pain in patients with multiple sclerosis.
Design Randomised double blind placebo controlled crossover
trial.
Setting Outpatient clinic, University Hospital of Aarhus,
Denmark.
Participants 24 patients aged between 23 and 55 years with
multiple sclerosis and central pain.
Intervention Orally administered dronabinol at a maximum
dose of 10 mg daily or corresponding placebo for three weeks
(15-21 days), separated by a three week washout period.
Main outcome measure Median spontaneous pain intensity
(numerical rating scale) in the last week of treatment.
Results Median spontaneous pain intensity was significantly
lower during dronabinol treatment than during placebo
treatment (4.0 (25th to 75th centiles 2.3 to 6.0) v 5.0 (4.0 to 6.4),
P = 0.02), and median pain relief score (numerical rating scale)
was higher (3.0 (0 to 6.7) v 0 (0 to 2.3), P = 0.035). The number
needed to treat for 50% pain relief was 3.5 (95% confidence
interval 1.9 to 24.8). On the SF-36 quality of life scale, the two
items bodily pain and mental health indicated benefits from
active treatment compared with placebo. The number of
patients with adverse events was higher during active treatment,
especially in the first week of treatment. The functional ability of
the multiple sclerosis patients did not change.
Conclusions Dronabinol has a modest but clinically relevant
analgesic effect on central pain in patients with multiple
sclerosis. Adverse events, including dizziness, were more
frequent with dronabinol than with placebo during the first
week of treatment.
