Specific hypotensive and antihypertensive ocular effects of d-isoproterenol in rabbits

d-Isoproterenol (ISO) applied topically to the rabbit eye specifically lowered intraocular pressure. Thus, it effectively reduced normal intraocular pressure and inhibited intraocular pressure elevation induced by water load without causing other obvious local or systemic pharmacologic effects. By comparison, dl-ISO was pharmacologically nonspecific in that amounts required to reduce intraocular pressure also produced significant and marked tachycardia. Furthermore, maximal intraocular pressure reduction was less with dl-than with d-ISO. Accordingly, and in consideration of reported clinical experience with dl-ISO in glaucomatous man, the d-isomer should be the preferred form of ISO for treating glaucoma. d-ISO should offer advantages over any other topical medication used currently in the treatment of this condition. Toxicity studies employing large, topical doses of drug in rabbit eyes showed that d-ISO was free from ocular irritation as well as systemic toxicologic effects and should be safe for controlled studies in man.