The effect of Tetrahydrocannabinol on optic nerve head blood flow in healthy subjects

Abstract

AbstractPurposeThere is ample evidence that optic nerve head blood flow (ONHBF) is impaired in patients with glaucoma. Tetrahydrocannabinol (THC) is used in the treatment for glaucoma in some countries for several years due to its intraocular pressure (IOP) lowering effect. Beside its IOP lowering potential, THC features neuroprotective effects and may improve ocular hemodynamics. The aim of the present study was to investigate whether oral administration of THC alters ONHBF in healthy subjects.MethodsThe present study was carried out in a double‐masked, randomized, placebo‐controlled, two‐way crossover design in 24 healthy subjects. For each study participant, two study days were scheduled, on which they either received capsules containing 5 mg Dronabinol (a synthetic THC) or placebo capsules identical in appearance. ONHBF was assessed using laser Doppler flowmetry at baseline and 1 hr after drug administration. Ocular perfusion pressure (OPP) was calculated as 2/3*mean arterial pressure (MAP) ‐ IOP.ResultsTwenty‐four healthy subjects (12 female and 12 male) aged between 20 and 35 years participated in the present study. The study medication was well tolerated and no cannabinoid‐related psychoactive effect was observed. Neither administration of THC nor placebo had an effect on IOP, MAP or OPP. In contrast, THC significantly increased ONHBF by 9.5 ± 8.1% whereas placebo did not show a change in ONHBF (0.3 ± 7.4 % vs. baseline, p < 0.001 between groups).ConclusionsThe present data indicate that orally administered, low dose THC increases ONHBF in healthy subjects without affecting IOP, OPP or inducing psychoactive side effects. Further studies are needed to investigate whether this effect can also be observed in patients with glaucoma.