Clinical study explores the effects of cannabis on chronic pain

‘If cannabis truly offers relief from chronic pain, that would be good news’, says Dr Marieke Niesters, Associate Research Director Pain at CHDR and pain specialist at Leiden University Medical Center (LUMC). ‘In light of the current opioid crisis, there is a search for analgesic compounds acting on other neurotransmitter systems than the opioidergic system’.

In the Netherlands, there is a medicinal cannabis program ensuring the provision of safe and legal cannabis, but the use of medicinal cannabis for chronic pain is not reimbursed. Therefore, patients who benefit from the drug encounter high costs for its use. CHDR and LUMC are currently conducting a clinical study among 200 patients of LUMC’s outpatient pain clinic, in the hope of obtaining more clarity on the effectiveness of cannabis on pain relief. The study is financed by a grant from the Dutch medicinal cannabis program.

The study uses a cannabis-based preparation containing the active ingredient THC (delta-19 tetrahydrocannabinol) and the terpenes that give cannabis its characteristic smell and taste. The placebo contains only the terpenes and no THC. Neither preparation includes other cannabinoids such as CBD (cannabidiol).

Participants will be randomised to receive either the THC-containing preparation or the placebo for five weeks, followed by a washout period, after which they switch to the other treatment for another five weeks. ‘Patients are free to increase or decrease the initial dose they receive to achieve the desired effect and minimise any side effects,’ explains Niesters.

At set times during the study, participants complete regular assessments, including pain and quality-of-life questionnaires. Additionally, they undergo extensive testing using the Quantitative Sensory Testing (QST) method, which maps the function of both the central nervous system and the peripheral nervous system. Niesters and her colleagues at the LUMC are specialised in the application of this refined diagnostic technique.

‘By carefully characterising patients’ pain systems and their response to both THC and placebo, we hope to gain a clearer understanding of the effects of THC on chronic pain,’ says Niesters. ‘We also aim to identify biomarkers that could predict if someone may benefit from THC. This study not only highlights the potential role of medicinal cannabis, but also the value of QST in advancing pain drug development. Thanks to the combined expertise of CHDR and LUMC, we can continue to contribute to the development of new treatments for chronic pain in the future.’