Effects of Cannabinoids on Intraocular Pressure When Added in Combination With Timolol, Dorzolamide or Brimonidine in a Rat Glaucoma Model

Abstract

 

Methods:

 

Surgical ligation of three of the four episcleral veins in one eye of Sprague Dawley rats caused a sustained (>44 wk) IOP increase. IOP was measured by Tonolab^TM at baseline and after 30, 60 and 120 min, as was heart rate and blood pressure. For combination therapy, after baseline IOP measurement, timolol 0.5%, brimonidine 0.1% or dorzolamide 2.0% was applied topically followed 10 min later by O-1812 1.0%, or O-2545 1.0%. An assessment for ocular irritation was performed by slit lamp examination at baseline and after 120 min.

 

Results:

 

Compared to baseline, within 30 min all drugs and combinations significantly decreased IOP (p<0.05). Among the single drug regimen, O-1812 and dorzolamide had the greatest effect at 30 min. All, except brimonidine, maintained a significant IOP reduction for up to 120 min. No additive effects were seen with combination therapy. Both timolol and dorzolamide actually decreased the effect of O-1812. Timolol also decreased the effect of O-2545. No drug alone or in combination caused ocular irritation or systemic effects.  

 

Keywords: intraocular pressure • aqueous • trabecular meshwork