The purpose of this study was to assess the effect on intraocular pressure (IOP) and the safety and tolerability of oromucosal administration of a low dose of delta-9-tetrahydrocannabinol (Δ-9-THC) and cannabidiol (CBD).
A randomized, double-masked, placebo-controlled, 4 way crossover study was conducted at a single center, using cannabis-based medicinal extract of Δ-9-THC and CBD. Six patients with ocular hypertension or early primary open angle glaucoma received a single sublingual dose at 8 AM of 5 mg Δ-9-THC, 20 mg CBD, 40 mg CBD, or placebo. Main outcome measure was IOP. Secondary outcomes included visual acuity, vital signs, and psychotropic effects.
Two hours after sublingual administration of 5 mg Δ-9-THC, the IOP was significantly lower than after placebo (23.5 mm Hg vs. 27.3 mm Hg, P=0.026). The IOP returned to baseline level after the 4-hour IOP measurement. CBD administration did not reduce the IOP at any time. However, the higher dose of CBD (40 mg) produced a transient elevation of IOP at 4 hours after administration, from 23.2 to 25.9 mm Hg (P=0.028). Vital signs and visual acuity were not significantly changed. One patient experienced a transient and mild paniclike reaction after Δ-9-THC administration.
A single 5 mg sublingual dose of Δ-9-THC reduced the IOP temporarily and was well tolerated by most patients. Sublingual administration of 20 mg CBD did not reduce IOP, whereas 40 mg CBD produced a transient increase IOP rise.
*Department of Ophthalmology, Aberdeen Royal Infirmary
§School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, UK
†Cannabinoid Research Institute, Magdalen Centre, Oxford Science Park, Oxford OX4 4GA
‡GW Pharmaceuticals plc, Ely, Cambs CB7 4ZA
Supported by GW Pharmaceuticals, manufacturers of the sublingual cannabinoid used in this study, and the Grampian Glaucoma Fund.
Reprints: Augusto Azuara-Blanco, MD, PhD, The Eye Clinic, Aberdeen Royal Infirmary, Aberdeen AB25 2ZN, UK (e-mail: firstname.lastname@example.org).
Received for publication February 27, 2006; accepted May 30, 2006