• Johannes Müller, Walter Plöchl, Birgit Reiter, Thomas Stimpfl, Alexandra Graf, Joanna Baron-Stefaniak, Lukas Infanger, and Thomas Hamp.
• From the Division of General Anaesthesia and Intensive Care Medicine, University Department of Anaesthesia, Intensive Care Medicine and Pain Medicine (JM, WP, JB-S, LI, TH), Clinical Department of Laboratory Medicine, Analytical Toxicology (BR, TS) and Institute of Medical Statistics, Medical University of Vienna, Vienna, Austria (AG).
• Eur J Anaesthesiol. 2021 Jan 1; 38 (1): 58-63.

BackgroundCannabis has increasingly been used for medical and recreational purposes. The main pharmacological compound in cannabis is tetrahydrocannabinol (THC), which has sedative, anxiolytic and analgesic effects. In some animal models, THC has also been shown to reduce the minimum alveolar concentration (MAC) of halothane and cyclopropane, but its effect on sevoflurane, currently the most commonly used inhalational anaesthetic agent, has not been investigated.ObjectiveTo investigate the effect of THC on the MAC of sevoflurane in rats.MethodsObserver-blinded, randomised controlled trial.SettingCentre for Biomedical Research of the Medical University of Vienna, 2019.IndividualsThirty-eight adult Wistar rats.InterventionsThe rats were allocated randomly into one of two groups. Group A received THC 10 mg kg and group B received the corresponding volume of placebo via gastric gavage (administration through a tube placed in the distal oesophagus). The rats were then individually anaesthetised in an airtight sevoflurane-flooded chamber, and the MAC in both groups was determined using Dixon's up-and-down method. Blood samples were drawn to measure serum concentrations of THC.Main Outcome MeasuresThe primary outcome was the MAC of sevoflurane in Groups A and B.ResultsThe bootstrap estimate of the MAC of sevoflurane was 2.1 (95% confidence interval 1.8 to 2.4) vol% in the THC group and 2.8 (95% confidence interval 2.7 to 2.9) vol% in the placebo group, corresponding to a significant MAC reduction of 26% in response to THC.ConclusionGastric administration of THC 10 mg kg significantly reduced the MAC of sevoflurane by 26%.Trial RegistrationNot applicable.

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