Cannabinoids for Pain

The British Pain Society adds a rational voice to the debate and hype re cannabis and cannabinoids for pain. It confirms what studies and meta-analyses have generally found, that the evidence base for effectiveness is weak. Concerns are expressed for potential side effects especially in terms of misuse, and effects on cognition and mental health (experts have consistently warned on the dangers in teenagers and use during pregnancy).

The Society feels that there is no evidence to support routine use in pain management but acknowledges their use when other modalities fail, and provides strict advice on monitoring and supporting such patients, with a plan to withdraw them when shown ineffective.



Propofol vs. Inhalational Anesthesia

A systematic review and meta-analysis finds that Propofol anesthesia provides better patient satisfaction, pain scores and an especially better nausea and vomiting outcome as compared with inhalational anesthesia, with a marginal increase in time for respiratory recovery and extubation.

While some recent studies have yielded opposing results on the effect of total intravenous anesthesia on cancer recurrence and mortality, there seems ample reason to choose Propofol based anesthesia. Further prospective validating studies are suggested.



Discontinuing Long-term Opioids in Chronic Pain

Judicious weaning and even discontinuing long term opioids in chronic pain is an option to discuss with patients. Whereas pain may not be fully controllable, quality of life is just as important and that includes the potential harms of opioids – addiction, overdose and death, falls, fractures, constipation, reduced libido, infertility, osteoporosis, sleep-disordered breathing, depression and motor vehicle accidents (link)

This retrospective review suggests that pain is no worse after discontinuing long term opioids especially in mild or moderate pain and may in fact slightly improve. Mechanisms involved may include tolerance and/or hyperalgesia.  The authors caution that nonetheless such patients may remain at risk for mental illness or suicide and careful psychosocial follow up is mandatory, as well as multimodal pain management strategies including non-pharmacological methods.


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Cannabis based medicines for chronic pain

A cautionary tale on cannabis use and users paralleling opioid users for questionable benefit. It is unlikely that cannabinoids are highly effective for chronic non-cancer pain.

“The absence of any clinically relevant beneficial effects of CBM in most systematic reviews, the presence of clinically relevant side effects, and the concerns about long-term risks, make it the duty of physicians prescribing CBM for chronic pain conditions to document and monitor patients carefully by following recent clinical practice guidelines.”



Amitriptyline for Back Pain

This randomized controlled study of 146 patients sought to elucidate the effectiveness of a long used chronic low back pain treatment. It has been variously and confusingly reported as Amitriptyline “may be useful” or that it is not of much use. The findings are not overwhelmingly supportive: “amitriptyline did not demonstrate an improvement in pain, disability, or work at 6 months compared with an active comparator. However, there was a reduction in disability at 3 months, an improvement in pain intensity that was nonsignificant at 6 months, and minimal adverse events reported for the treatment group”.

25mg was the dose and further studies could assess dose escalation. The comparator Benztropine may have confounding effects.



Chronic Pain Suicide Link

While this analysis is retrospective, it provides a concerning correlation between suicide and chronic pain, many dying from firearms or opioid overdose. Somewhere in the region of 10% had prior chronic pain. The study concludes: “Chronic pain may be an important contributor to suicide. Access to quality, comprehensive pain care and adherence to clinical guidelines may help improve pain management and patient safety.”



Transversus Abdominis Plane Block in Children

“In children, quality of postoperative pain control provided by transversus abdominis plane (TAP) block using levobupivacaine 0.4 mg·kg−1 administered as either 0.2% or 0.4% did not differ and was associated with a very low risk of local anesthetic systemic toxicity”. The study involved inguinal day surgery and about 70% did not require any postoperative opioids. However the study only compared the two concentrations, there being no comparison with a control group not given the TAP block.