NEBULIZED BETA(2)-ADRENOCEPTOR AGONISTS DO NOT AFFECT PLASMA SELENIUMOR GLUTATHIONE-PEROXIDASE ACTIVITY IN PATIENTS WITH ASTHMA

We investigated whether the beta(2)-agonists fenoterol and salbutamol decreased plasma selenium and glutathione peroxidase activity in patie nts with asthma as this may partially explain the findings of reduced selenium status in asthmatic patients. Nine patients with asthma were studied on 3 occasions and inhaled either fenoterol (5 mg), salbutamol (5 mg) or ipratropium bromide (0.5 mg) administered by nebulization u sing a randomized, double blind, crossover design. Plasma selenium, gl utathione peroxidase activity and potassium were measured prier to dru g administration and at 15, 30 and 60 minutes after drug. None of the drugs had any effect on plasma selenium or glutathione peroxidase acti vity. Ipratropium bromide did not affect plasma potassium. Both beta(2 )-agonists significantly decreased plasma potassium. The mean (SD) max imum decrease was -0.79 (0-18) mmol/l for fenoterol and -0.26 (0-03) m mol/l for salbutamol (both p less than or equal to 0.01) confirming sy stemic absorption of the drugs. beta(2)-agonists are unlikely to be re sponsible for the reduced selenium status found in some patients with asthma.