CIESAL researchers and Department of Anesthesiology publish protocol on cannabis-based medicines


The protocol is for a Cochrane systematic review on cannabis-based medicines for the prevention of postoperative nausea and vomiting.

CIESAL researchers, Jana Stojanova, Javier Pérez, Juan Franco and Eva Madrid, and researcher Bruno Caracci, from the Department of Anesthesiology, have published a protocol for a systematic review to evaluate the efficacy of cannabis-based medications in preventing postoperative nausea and vomiting in adults. The systematic review applies the Cochrane methodology, recognised as having high quality standards. The researchers hope to definitively answer the question of whether drugs of this type provide a benefit in this common scenario.

Postoperative nausea and vomiting following general anesthesia are considered significant outcomes due to their high frequency, clinical impact, and effect on patient satisfaction. They occur in up to 30% of patients during the postoperative period and their incidence rises to 80% in high-risk patients. The pathophysiology of postoperative nausea and vomiting is complex and involves peripheral and central receptors. The “functional vomiting centre,” commonly known as the “vomiting centre,” is activated by projections from the chemoreceptor trigger zone, cortical structures, gastrointestinal vagal afferents, and the vestibular system. Specific stimuli that hijack these pathways in the perioperative period include surgical trauma and inflammation, inhalational anesthetics, opioids, and altered gastrointestinal motility.

Although numerous prophylactic antiemetic strategies exist, this condition remains an important clinical challenge. For this reason, the Cochrane Library has decided to accept the registration of this proposal, led by Jana Stojanova, given that its results will contribute to the better health of patients with this condition.

Although cannabis-based medicines are rarely used in clinical practice, recent research on public perceptions suggests that participants would accept them in mainstream medicine. In the context of acute postoperative pain, participants reported that they would be willing to try cannabis-based medicines, with 81% stating that they believed they would be effective. A UK population study reported that 76% of participants would take cannabis-based medicines if prescribed (Public Perceptions to Cannabis). Additionally, recent legislative changes to facilitate access to cannabis‐based medicines for specific indications globally have stimulated research efforts.

This systematic review protocol aims to evaluate the efficacy as well as the safety of cannabis-based medicines, compared to placebo or alternative treatments, for preventing nausea and vomiting during the postoperative period for adult patients undergoing elective surgery.

Therefore, we hope that ongoing studies addressing the use of cannabis-based medicines to prevent postoperative nausea and vomiting will produce evidence and results that will enable us to continue with our main task of generating evidence synthesis for decision-makers in Chile and throughout the world.

The protocol has been published in the Cochrane Library: