An in-service investigation of the additive effect of topical adrenergic agonists and beta-blockers.

Abstract

We assessed the long-term additive effect of topical adrenaline or adrenaline precursor and beta-blockers because of doubts as to the presence and persistence of such an effect. In 43 patents (20 males and 23 females; mean (+/- SD) age 68.4+/-11.5 years, range 24-84 years) on combined therapy for a mean 4.6+/-4.4 years (range 3 months to 17 years) for chronic open-angle glaucoma, the adrenaline or adrenaline precursor drop was stopped for 4 weeks in both eyes of 27 patients and in one eye of 6 patients. There was a mean rise in intra-ocular pressure (IOP) for the whole group from 17.5+/-4.0 to 18.7+/-4.9 mmHg (range 10-28 and 9-31 mmHg, respectively) on stopping adrenergic agonist drops. Three different responses were identified: (i) a rise in IOP > 2 mmHg (mean 5.8+/-3.2 mmHg; range 3-14 mmHg) in 20 eyes of 15 patients; (ii) no rise or fall > 2 mmHg in 43 eyes of 23 patients, with a mean rise of 0.2+/-1.1 mmHg; and (iii) a fall in IOP of > 2 mmHg (mean 5.6+/-3.2 mmHg; range 3-11 mmHg) in seven eyes of five patients. The effect of adrenergic agonist and beta-blocker drops is variable, but an additive effect may be strong and persistent n some eyes, suggesting considerable variation in the distribution and density of adrenoceptors in different eyes. Therefore, there may be some variation in the effect of new alpha2-adrenoceptor agonists, but such effects should be additive to those of beta-blockers.