Analgesic Efficacy of Smoked Cannabis

May 18, 2011

In a ran­dom­ized, double-blinded, placebo con­trolled, crossover trial in fif­teen healthy vol­un­teers, we eval­u­ated the effects of low, medium, and high dose smoked cannabis (respec­tively 2%, 4%, and 8% 9-delta-tetrahydrocannibinol by weight) on pain and cuta­neous hyper­al­ge­sia induced by intra­der­mal cap­saicin. Cap­saicin was injected into oppo­site fore­arms 5 and 45 min­utes after drug expo­sure and pain, hyper­al­ge­sia, tetrahy­dro­can­nib­i­nol plasma lev­els, and side effects were assessed.

Five min­utes after cannabis expo­sure, there was no effect on capsaicin-induced pain at any dose. By 45 min­utes after cannabis expo­sure, how­ever, there was a sig­nif­i­cant decrease in capsaicin-induced pain with the medium dose and a sig­nif­i­cant increase in capsaicin-induced pain with the high dose. There was no effect seen with the low dose nor was there an effect on the area of hyper­al­ge­sia at any dose. Sig­nif­i­cant neg­a­tive cor­re­la­tions between pain per­cep­tion and plasma delta-9-tetrahydrocannibinol lev­els were found after adjust­ing for the over­all dose effects. There was no sig­nif­i­cant dif­fer­ence in per­for­mance on the neu­ropsy­cho­log­i­cal tests.

This study sug­gests that there is a win­dow of mod­est anal­ge­sia for smoked cannabis with lower doses decreas­ing pain and higher doses increas­ing pain.

The full results of this study were pub­lished in the jour­nal Anes­the­si­ol­ogy.

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