[Asthma and beta-blocker eye drops (timolol, metipranolol, carteolol). Inhibition of chronotropic effects of isoprenaline].

Effects of three beta antagonist eye drops are studied in three parallel groups of asthmatic patients. Each ocular topic lowers FEV1 with a maximal effect of -13.4 +/- 2.1% for timolol (n = 15), -17.9 +/- 3.3% for metipranolol (n = 10), and -8.6 +/- 3.0% for carteolol (n = 10). Vital capacity, systolic and diastolic pressure scarcely change, but all three eye drops give a dose dependent sinus bradycardia. Intravenous infusion of isoproterenol (exclusive beta agonist) shows an important inhibition of cardiac receptors by timolol. Doses necessary to increase heart rate of 50% are of 0.242 +/- 0.019 microgram/kg before eye drops are instilled and of 0.647 +/- 0.054 microgram/kg after timolol treatment. This study stresses out the necessity of following recommended doses and respecting carefully classical contra indications of beta blocking agents and specially asthma.