Oral haloperidol lowers human intraocular pressure.

This is a double masked, randomized, crossover design trial of orally administered haloperidol in human volunteers. There was a statistically significant drop of the intraocular pressure in non-glaucomatous volunteers at 3 and 4 hours following haloperidol administration. Glaucomatous patients on topical medications did not show a statistically significant drug effect. Non-glaucomatous volunteers showed a statistically significant decrease in pupillary diameter 3 hours following haloperidol administration while glaucomatous subjects showed no significant change in pupillary diameter. There were no significant changes in the near point of accomodation. Dopamine antagonists like haloperidol may act by blocking post-synaptic dopamine receptors in the ciliary body, resulting in vasoconstriction and subsequently decreased aqueous humor production. Pharmacologic data from human use suggests that ocular side effects of topically administered haloperidol may be less than those of pilocarpine, while systemic side effects may be less than those of timolol. Haloperidol may become a cost-effective, once daily ocular hypotensive agent. Problems with preparation of a viable topical vehicle, as well as potential long-term side effects will require a great deal of further investigation.