A submicron emulsion of HU-211, a synthetic cannabinoid, reduces intraocular pressure in rabbits

Purpose: To study the ocular hypotensive effect of a nonpsychotropic cannabinoid, HU-211 (11-hydroxy-Δ8-tetra-hydrocannabinol, dimethylheptyl), an N-methyl-D-aspartate (NMDA) agonist, in normotensive rabbits. Methods: The cannabinoid HU-211, being lipophilic, was incorporated into a stable oil-in-water submicron sterile emulsion, consisting of 0.12% (w/w) HU-211. A single- dose, randomized and double-masked study was designed, using a Digilab 30R pneumotonometer to measure intraocular pressure (IOP) in normotensive rabbits. Results: Application of a single dose of HU-211 ophthalmic preparation resulted in an IOP reduction of 5.3 mmHg (24% of baseline), first evident at 1.5 h post application and persisting for over 6 h. A small but significant lowering of pressure (12.5% of baseline) occurred in the contralateral eyes of HU-211 treated rabbits, lasting for 4 h post treatment. Conclusion: Our work demonstrated that HU-211, incorporated into submicron emulsion, caused a 6-h-long reduction in IOP in the treated eye, with a lesser reduction in the contralateral untreated eye.