Acepromazine. Effects on intraocular pressure.

We investigated the effects of the topical application of acepromazine maleate on the intraocular pressure (IOP) in 27 adult rhesus monkeys. The monkeys were divided into two groups: group 1 (16 monkeys) had both eyes normal, and group 2 (11 monkeys) had experimental chronic glaucoma in one eye and a normal fellow eye. One drop of 1% acepromazine maleate solution was instilled in one eye of monkeys in group 1 and in the glaucomatous eye of monkeys in group 2; the other eye served as the control. The IOP was measured before drug administration and 1, 4, 8, 24, and 32 hours after, with detailed slit-lamp examination of the anterior segment. Acepromazine produced no change in IOP in eyes in group 1, but it produced a fall in pressure in all eyes with high IOP in group 2, evident 1 hour after instillation, maximal between 4 and 8 hours, and still remaining after 32 hours. The pupil showed no change in size, but a transient ptosis was observed in the treated eye in all monkeys.