The Pharmacy Read List: March 16th Edition

It’s one of the busiest times of the year for pharmacy students, but we’ve managed to put together yet another Read List for you, readers! This week, team member Ainge does a great job of breaking down a randomized, double-blind, placebo-controlled trial testing venlafaxine XR in subjects with both spinal cord injury and major depressive disorder and explains the benefits of analyzing population and disease state subgroups. Have a read below.

The Read List is (usually) a biweekly update on pharmaceutical literature. Every two weeks we handpick one of the most relevant and interesting pharmacy-related publications and summarize it for your convenience. At the end of every month, a quiz on that month’s content will be released. Simply take the quiz, and you’ll be automatically entered into a draw for a gift card prize!

Instructions to access:  Access through UBC Library: http://www.sciencedirect.com.ezproxy.library.ubc.ca/science/article/pii/S0003999314013069 or click on the link below to access the article when on the campus network.

Efficacy of Venlafaxine XR for the Treatment of Pain in Patients With Spinal Cord Injury and Major Depression: A Randomized, Controlled Trial

Patients with spinal cord injuries (SCI) frequently report pain (with 65-85% prevalence), which can be categorized as nociceptive and neuropathic pain types. SCI-related neuropathic pain can be quite severe and difficult to treat; anticonvulsants and antidepressants are considered the main pharmacotherapy agents for neuropathic pain but evidence is still lacking. As antidepressants seem to have some potential to relieve SCI-related neuropathic pain, Richards et al. designed a depression treatment trial with the secondary goal of testing the effect of venlafaxine XR on neuropathic pain. This double-blind, randomized, placebo-controlled trial enrolled 133 SCI patients with at least mild major depressive disorder (MDD) from 2007-2012 at 6 American SCI centers where patients were assigned randomly 1:1 to 12 weeks of active treatment (venlafaxine XR) or inactive placebo. Pain intensity and interference was assessed at baseline, 6, and 12 weeks. The effect of venlafaxine XR on neuropathic pain proved similar to that of placebo; it did not have a consistent beneficial effect on neuropathic pain in individuals with SCI and MDD.  However, venlafaxine XR resulted in statistically significant and clinically meaningful reductions in nociceptive pain site intensity and pain interference even after controlling for anxiety, depression, and multiple pain sites within the same individual. Specifically, at 12 weeks, 50% of those receiving venlafaxine XR had at least a 50% decrease in pain intensity compared with only 24% for placebo. For those who achieved a minimally effective dose of venlafaxine XR (150mg/day), some additional evidence of effectiveness was noted for those with mixed (both neuropathic and nociceptive) pain sites. Because all subjects here had MDD, it is uncertain whether the outcomes can be generalized to SCI patients without MDD. Research is needed to replicate these findings and determine whether the antinociceptive effect of venlafaxine XR generalizes to persons with SCI pain without MDD. The magnitude of the response seen here for nociceptive pain suggests that it might have considerable benefit for routine clinical use, especially in persons with SCI and MDD. Given the relatively benign adverse effect profile of venlafaxine, it would present a marked benefit over opioids with their negative side effects, and could represent an additional agent to add with NSAIDs and other approaches. This study also illustrates the importance of examining subtypes of SCI pain in intervention research. Studies that fail to do so are at risk for producing negative findings for interventions that may work selectively for one subtype of SCI pain and not another.

– Ainge Chang
B.Sc. (Pharm) Candidate 2016

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