Effects of concomitant administration of latanoprost and pilocarpine on the intraocular pressure of experimentally glaucomatous rabbits

The purpose of this study was to evaluate the effects of a combination of latanoprost and pilocarpine on the intraocular pressure in experimentally glaucomatous rabbits. Ocular hypertension was induced in 11 conscious rabbits by the oral administration of tap water (70 mL/kg) via an orogastric tube. The study was conducted in three therapeutic groups to test the effects of latanoprost (group L), pilocarpine (group P) and a combination of the two drugs (group LP). After evaluating the first drug, a washout period of 1 week was allowed before the second drug was evaluated. The left eye of rabbits in group L received one drop of normal saline and one drop of 0.005% latanoprost, in group P one drop of normal saline and one drop of 2% pilocarpine and in group LP, one drop of 0.005% latanoprost and one drop of 2% pilocarpine. The right eyes of all rabbits received two drops of normal saline (as control eyes). The intraocular pressure (IOP) and pupil diameter (PD) were measured before and at 0, 15, 30, 45, 60, 75, 90, 105 and 120 min post-water loading. The results showed that eyes, which received pilocarpine had a significantly lower increase in IOP at 15, 30, 45 and 60 min after drug administration compared to placebo eyes, whereas groups L and LP did not prevent an IOP increase. The PD decreased in groups P and LP throughout the study, whereas it did not change in group L. It was concluded that the topical administration of latanoprost alone or in combination with pilocarpine appeared to have no effect on IOP in acute ocular hypertensive rabbits.