Treatment of ocular hypertension and glaucoma with dopamine antagonists.

A group of dopamine antagonists have been studied for their ability to suppress the intraocular pressure (IOP) recovery rate of rabbits infused with hypertonic saline. All dopamine antagonists examined were either equipotent or more potent than beta-adrenergic blocker, timolol, to lower the IOP in the following order: haloperidol greater than moperone = trifluperidol greater than clofluperol = pipamperone = lenperone = timolol. Contrary to timolol, haloperidol, moperone and trifluperidol relaxed histamine pretreated guinea pig tracheal muscle at doses as low as 0.03-1.0 microgram/ml, whereas cardiac contractility and heart rate were little suppressed at doses up to 3 micrograms/ml. Since dopamine antagonists do not block the beta-adrenergic receptors and the ophthalmic dose required to lower IOP is only a small fraction of the antipsychotic doses, it is concluded that dopamine antagonists could be used for glaucoma treatment with little noticeable side effects, if any.