Pain intensity of chronic non-cancer patients was reduced by cannabinoids consumption , but effect sizes were small .
Efficacy for neuropathic and non-neuropathic pain was similar
There is growing interest in using cannabinoids for chronic pain .
We performed a systematic review and meta- analysis of r and omized controlled trials to evaluate the analgesic efficacy and adverse effects of cannabinoids for chronic non-cancer pain .
An efficient randomised, placebo-controlled clinical trial with the irreversible fatty acid amide hydrolase-1 inhibitor PF-04457845, which modulates endocannabinoids but fails to induce effective analgesia in patients with pain due to osteoarthritis of the knee
Summary A r and omised , placebo‐controlled clinical trial with PF‐04457845 , a novel irreversible fatty acid amide hydrolase‐1 inhibitor , increases endocannabinoids , but does not induce analgesia in patients with osteoarthritis . Abstract The effect of PF‐04457845 , a potent and selective fatty acid amide hydrolase‐1 ( FAAH1 ) inhibitor , on  pain due to osteoarthritis of the knee was investigated in a r and omised placebo and active‐controlled clinical trial . The trial involved 2 periods ( separated by a 2‐week washout ) consisting of a 1‐week wash‐in phase followed by 2 weeks double‐blind treatment . Patients received single‐blind placebo throughout the wash‐in and washout periods . Patients were r and omised to receive either 4 mg q.d . PF‐04457845 followed by placebo ( or vice versa ) , or 500 mg b.i.d . naproxen followed by placebo ( or vice versa ) . The primary end point was the Western Ontario and McMaster Universities Osteoarthritis Index ( WOMAC ) pain score . The trial had predefined decision rules based on likelihood that PF‐04457845 was better or worse than the st and ard of care ( considered to be a 1.8 reduction in WOMAC pain score compared to placebo ) . A total of 74 patients were r and omised to 1 of 4 treatment sequences . The mean differences ( 80 % confidence intervals ) from placebo in WOMAC pain score were 0.04 ( −0.63 to 0.71 ) for PF‐04457845 and −1.13 ( −1.79 to −0.47 ) for naproxen , indicating that whilst naproxen seemed efficacious , PF‐04457845 was not differentiated from placebo . The study was stopped at the interim analysis for futility . PF‐04457845  decreased FAAH activity by > 96 % and substantially increased 4 endogenous substrates ( fatty acid amides ) . PF‐04457845 was well tolerated in osteoarthritis patients , and there was no evidence of cannabinoid‐type adverse events . The lack of analgesic effect of FAAH1 inhibition in humans is in contrast to data from animal models . This apparent disconnect between species needs further study
Pain intensity of chronic non-cancer patients was reduced by cannabinoids consumption , but effect sizes were small .
Efficacy for neuropathic and non-neuropathic pain was similar
There is growing interest in using cannabinoids for chronic pain .
We performed a systematic review and meta- analysis of r and omized controlled trials to evaluate the analgesic efficacy and adverse effects of cannabinoids for chronic non-cancer pain .