Dose response to inhaled terbutaline powder and peak inspiratory flow through Turbuhaler® in children with mild to moderate asthma

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Abstract
The purpose of this study was to investigate the relative effectiveness of 0.25 mg, 0.5 mg, and 1.0 mg of terbutaline, administered via Turbuhaler®, in children with mild to moderate asthma, and to register peak inspiratory flow rates through Turbuhaler® (PIFTBH). Thirty‐seven children in Portugal (one center) and 45 children in Sweden (one center) aged 3–10 years participated in two separate, double‐blind, placebo‐controlled, crossover, and randomized studies of the same design. Because of differences in other therapies for asthma and climate, combination of the two studies into one metanalysis did not appear appropriate. The children inhaled 0.25 mg, 0.5 mg, and 1.0 mg terbutaline sulfate and placebo t.i.d. for consecutive 2‐week periods without washout periods. Peak expiratory flow rates (PEF) were measured at home before and 15 minutes after each inhalation in the morning, afternoon, and evening. PIFTBH was measured twice at each of four clinic visits. At the Portuguese center the increases in mean morning PEF from before to after inhalation were 32 L/min after 0.25 mg, 35 L/min after 0.5 mg, and 40 L/min after 1.0 mg. The corresponding figures in Sweden were 26 L/min, 31 L/min, and 29 L/min after 0.25 mg, 0.5 mg, and 1.0 mg, respectively. For children 3–6 years, mean values for PIFTBH were 60 L/min in Portugal (n = 15), and 58 L/min in Sweden (n = 23). In the 7–10 year group the mean PIFTBH was 72 L/min (n = 22) in Portugal, and 68 L/min (n = 22) in Sweden. We conclude that inhalation of terbutaline sulfate via Turbuhaler® at a small dose of 0.25 mg resulted in good bronchodilation and was comparable to inhalations of 0.5 mg and 1.0 mg in children aged 3–10 years with mild to moderate asthma. PIFTBH were comparable to values previously recorded in healthy 6‐year‐old and older children and in adult asthmatic patients. Pediatr Pulmonol. 1996; 22:106–110.