[Treatment with betaxolol and placebo eyedrops in patients with glaucoma and reactive airway diseases].

The study communicated here was designed to evaluate the absence of pulmonary beta-blockade as detected by a histamine provocation in betaxolol-treated patients suffering from open-angle glaucoma and coexisting obstructive airway disease. The study was a randomized, double-masked crossover trial, comparing betaxolol 0.5% ophthalmic solution and placebo. Ten patients (4 male, 6 female) were eligible by demonstrating baseline off-therapy IOP values exceeding 22 mmHg and a FEV1 value that was reduced by 15% to 20% following histamine provocation. After an appropriate washout period, baseline IOP and pulmonary function (FEV1, FVC) were tested. One drop of test medication (betaxolol or placebo) was instilled in both eyes; tonometry and a pulmonary function test were performed 90 minutes later. The patients then underwent a histamine provocation test. The concentration of histamine necessary to reduce FEV1 and FVC by 15% to 20% was recorded. The IOP was significantly reduced in patients treated with betaxolol, but not in those given placebo. FEV1 and FVC values 90 minutes after treatment with betaxolol or placebo were not significantly different from baseline values. After histamine provocation the FEV1 was, as expected, significantly decreased from baseline (15% to 20%) in both treatment groups. There was no statistical difference in the histamine concentration necessary to reduce the FEV1 by 15% to 20% between placebo (5.60 mg/ml) and betaxolol (5.25 mg/ml) treatments. This demonstrates that betaxolol has no pulmonary beta-blocking effect. Our study suggests that ophthalmic treatment with betaxolol in patients with glaucoma and obstructive airway disease enhances pulmonary safety due to the beta-1 cardioselective action of the drug.