The Effect of Corynanthine on Intraocular Pressure in Clinical Trials

A single drop, dose-response, double-masked study of the effect of corynanthine, a selective α1 adrenergic antagonist, on intraocular pressure (IOP) was carried out in 10 symmetrically ocular hypertensive patients. Corynanthine 1 % had no significant pressure lowering effect. Topical application of a 2% solution significantly (P < 0.05) reduced IOP for at least eight hours; at five hours; mean IOP (±SEM) was 20.6 ± 2.0 mmHg and 26.0 ± 4.9 mmHg, comparing treated and control eyes, respectively. The 5% solution caused a significant (P ± 0.05) bilateral reduction in IOP, comparing treated and control eyes to baseline IOP respectively. Two percent corynanthine applied topically two or three times daily for one, two, or three weeks to seven patients with symmetrical ocular hypertension did not reduce IOP. Alpha adrenergic antagonists may have a role in the treatment of glaucoma.