Prescribing for chronic pain: opioids and medical cannabis (Part Two)

Addiction

One of the key urgencies in moving away from an opioid-based long-term treatment plan is their addictive nature, and the potential for this addiction to negatively harm patients in the course of treatment. This poses the key question: is medical cannabis any better as an alternative?

While some evidence has been found across withdrawal experienced by cannabis users, the symptoms are noticeably mild in comparison to those of opioid addiction. Withdrawal symptoms in cannabis users have been noted to include irritability, anxiety, sleep disturbance, appetite changes, depressed mood, nausea, headaches and abdominal pain. However, these symptoms are not experienced by all cannabis users, and much of this research has been derived from studies across patients who already had substance abuse disorders, and who are unlikely to commit to a regular and supervised long-term treatment regime.[2]

Long-term side effects

While research is still underway as to potential long-term side effects of cannabis use, habitual smokers of cannabis have been found to be more likely to suffer from chronic bronchitis[3] as well as lung cancer[4]. The important note here, however, is that the majority of these studies have been conducted on long-term cannabis used via those whose main method of taking the drug is via smoking, and who are also ongoing tobacco smokers. This means that the research has found it difficult to delineate cannabis use and cardiopulmonary issues. 

Another area of consideration regarding long-term side effects of cannabis use is the impact on the brain. An abundance of research has found links between long-term and substantial (such as daily) cannabis use with the development of psychiatric disorders – in particular, schizophrenia. However, it’s also noted that this linkage is most commonly seen in those with a pre-existing genetic trait.[5] As well, current recommendations for THC dosage prescription sit at 5-20mg/day[6], which is a mere fraction of the amount a habitual cannabis smoker would consume – therefore, this linkage requires further examination within the specificity of medical usage and its parameters. Because there are potential adverse effects on the development of the brain, the prescription of CBD and THC in patients who are under 16 is recommended to be carefully considered and monitored.[7]

Drug interactions

Due to the ongoing nature of studies across the medical and pain-treating capacities of cannabis, the full suite of drug interactions with its active ingredients remains currently unknown. There’s an increasing need and incentive for clinical trials and associated drug studies, thanks to the strength of early findings and results, and the improvements reflected by many clinical study participants and private users of cannabis oil for pain treatment. Currently, opioids have documented interactions which are relatively well understood, allowing qualified pharmacists to provide advice within specific treatment plans.

It’s common knowledge that the combination of any sedating drugs, such as cannabis and opioids, can increase the risk of driving accidents.

Evidence exists that demonstrates that THC can interact with warfarin, and patients who use THC may be more prone to bruising, nose-bleeds, and sensitive drugs, meaning they should be carefully monitored.[8],[9]

Fatigue and driving

Across all pain management strategies is the importance of controlling for fatigue, so that patients on pain treatment plans can remain active within their limitations on a daily basis. There’s a core focus on driver safety, both for the patient themselves and for the wider community they’re driving within.

As with opioids, it’s crucial that great care is taken when using THC and driving. It goes without saying that patients should not drive if they’re feeling any side effects of drowsiness. Currently, laws around cannabis and driving are much stricter than the laws that surround prescription opioids. The current official health advice is to wait five days before driving after consuming THC, which causes ongoing difficulties for patients and doctors. It’s expected that this issue will likely face further political scrutiny in the future as the increase of legal,safe and socially acceptable cannabis usage continues.

Conclusion

Medical cannabis offers promise to many who are seeking a natural alternative or complementary treatment to opioid prescription. While there are currently many gaps in the literature surrounding medical cannabis usage, side effects and long-term impacts, the growing interest from patients, alongside the medical interest which is fuelling a wealth of research, will continue to provide further insights around best prescription usages, patient outcomes and ongoing best practices. Paul Glare, a pain specialist who has over 20 years of experience states that ‘there has been limited evidence from published clinical trials to date for the safety and efficacy of medicinal cannabis products, and large, well-designed clinical trials are urgently needed.’

The continued shifts in legal regulations will also lead to an ongoing expedition of cannabis’ use in many key areas, such as chronic pain treatment.

References
  1. https://www.tga.gov.au/media-release/over-counter-access-low-dose-cannabidiol
  2. https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2764234
  3. https://www.forbes.com/sites/alicegwalton/2014/10/07/what-20-years-of-research-has-taught-us-about-the-chronic-effects-of-marijuana/?sh=353f834517be
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4827335/
  5. https://www.drugabuse.gov/publications/research-reports/marijuana/there-link-between-marijuana-use-psychiatric-disorders
  6. https://www.nps.org.au/australian-prescriber/articles/prescribing-medicinal-cannabis
  7. https://www.nps.org.au/australian-prescriber/articles/prescribing-medicinal-cannabis
  8. https://pubmed.ncbi.nlm.nih.gov/30326170/
  9. https://www.webmd.com/drugs/2/drug-4069/coumadin-oral/details/list-interaction-details/dmid-2874/dmtitle-warfarin-cannabidiol-tetrahydrocannabinol/intrtype-drug
  10. https://www.abc.net.au/news/2019-09-29/medicinal-cannabis-thc-and-driving-laws-in-australia/11517648
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