Medicinal cannabis may be used to treat a number of different medical conditions from epilepsy and depression to anxiety and insomnia. One of the most common uses of medicinal cannabis, however, has been to manage pain. With that in mind, researchers from Colorado, USA decided to test the efficacy of Dronabinol for acute pain in patients with traumatic injury.

Dronabinol is a man-made version of Delta-9-Tetrahydrocannabinol (THC) that is available by prescription outside the United Kingdom. It is commonly used in conditions where THC is also commonly used, particularly to improve appetite in patients with cancer, but also pain.

This pilot study assessed the effects of dronabinol on opioid medication use in patients following physical trauma. The study looked back over time at trauma patients who were prescribed dronabinol to help pain control at a trauma centre in the United States. This group of patients were matched by age and cause of injury to similar patients (controls) who did not receive dronabinol. Researchers analysed the effects of dronabinol by assessing the amount of opioid medication taken in hospital by each group of patients.

Whilst past studies have examined the benefits of Dronabinol in treating pain, most of these studies assessed the treatment of chronic pain, cancer pain, HIV-associated neuropathy, and pain associated with multiple sclerosis. Whilst there are studies looking at the effects of cannabinoids such as THC in acute pain, the authors noted this was the first study to examine the effects of adjunctive dronabinol for acute pain associated with physical trauma.

Acute pain refers to relatively short-lived pain (lasting less than 3 months), often resulting from soft tissue damage. Whilst chronic and acute pain share some similarities there are some marked differences between them, particularly in the effectiveness of certain medications. Traumatic injury can manifest itself quite differently from other types of acute pain, such as post-operative pain, due to the unexpected nature of its onset and degree of injury.

How was pain measured?

Researchers assessed 66 patients admitted with acute pain as a result of traumatic injury to St Anthony Hospital and Medical Campus in Lakewood, Colorado. Half of these patients (33) were given Dronabinol in addition to a standard painkiller regimen, and half were not given Dronabinol (33).

The researchers calculated pain levels in patients by monitoring the change in opioid medication use. Also examined was the use of non-opioid pain killers (paracetamol, non-steroidal anti-inflammatory drugs, muscle relaxants, and gabapentin).

What were the Results?

The results showed a significant reduction in opioid medication requirements among patients given Dronabinol alongside their regular pain medication regimen. In comparison, in the control group (who were not given Dronabinol) opioid medication use was unchanged from the initial 0-48 hours of their admission.

Although the addition of Dronabinol did not lead to a reduction in pain scores, both groups experienced similar reductions in pain. The same pain reduction was achieved in the Dronabinol group, despite significantly reducing their opioid medication requirement.

This study, whilst promising, is limited by its design as Dronabinol was more likely to be prescribed to those with more pain and therefore using more opioid medications after their injury. The results of this cohort study have led the researchers to initiate a randomised controlled trial (the gold standard of clinical research) to assess in more detail the efficacy of Dronabinol for reducing opioid prescribing following traumatic injury to give more definitive answers.