The Effect of Orally Administered Low-Dose Dronabinol on Retinal Blood Flow and Oxygen Metabolism in Healthy Subjects

• Published in: Journal of ocular pharmacology and therapeutics Vol. 37; no. 6; p. 360
• Main Authors: Hommer, Nikolaus, Schmidl, Doreen, Kallab, Martin, Bauer, Martin, Werkmeister, René M, Schmetterer, Leopold, Abensperg-Traun, Marihan, Garhöfer, Gerhard
• Format: Journal Article
• Language: English
• Published: United States 01.07.2021
• Subjects: Administration, Oral; Adult; Blood Flow Velocity; Cannabinoid Receptor Agonists - administration & dosage; Cross-Over Studies; Dose-Response Relationship, Drug; Double-Blind Method; Dronabinol - administration & dosage; Female; Healthy Volunteers; Humans; Male; Oxygen - metabolism; Regional Blood Flow; Retinal Vessels - drug effects; Retinal Vessels - physiology; cannabinoids; randomized controlled clinical trial; Doppler optical coherence tomography; retinal blood flow; retinal oxygen extraction; dronabinol
• ISSN: 1557-7732
• DOI: 10.1089/jop.2020.0131

The present study was performed to investigate the effect of oral dronabinol, a synthetic tetrahydrocannabinol derivate, on retinal hemodynamics in healthy subjects in a randomized, double-masked, placebo-controlled, 2-way crossover design. Twenty-four subjects received 5 mg dronabinol on 1 study day and placebo on the other study day. Total retinal blood flow (TRBF) was measured using a custom-built Doppler Optical Coherence Tomography system. Oxygen saturation of major retinal vessels was measured with a commercially available Dynamic Vessel Analyzer. Based on these parameters, retinal oxygen extraction was calculated. Measurements were performed before and after drug administration on both study days. Placebo had no effect on TRBF, retinal arterial or venous oxygen content, and retinal oxygen extraction (  > 0.1 each). In contrast, dronabinol induced a significant increase in TRBF from 38.9 ± 6.1 to 40.7 ± 6.7 μL/min (  < 0.001), which was accompanied by a significant increase in retinal venous oxygen content (from 0.129 ± 0.008 to 0.132 ± 0.009 mL O /mL,  = 0.02). As no change in retinal arterial oxygen content occurred (  = 0.12), retinal oxygen extraction remained stable (2.2 ± 0.4 μL vs. 2.2 ± 0.4 μL O /min,  = 0.29). These results indicate that orally administered dronabinol increases TRBF in healthy subjects without altering retinal oxygen extraction. The drug may therefore be a candidate for improving perfusion in patients with ocular vascular disease.