Respiratory response and pharmacokinetics of intravenous salbutamol in infants with bronchopulmonary dysplasia

The effects of iv salbutamol on respiratory mechanics were studied in six infants with bronchopulmonary dysplasia. Salbutamol was infused at a dose of 30 μg/kg over 30 min in five infants; a sixth infant received 66.7 μg/kg over 4 min. Salbutamol caused improvement in total respiratory system compliance and in airflow resistance. There was no correlation between salbutamol serum concentration and pulmonary function. Elimination half-time appears to be dictated in these infants more by the distribution volume (V(d)) than by clearance (C₁). The area under concentration-time curve of salbutamol correlated inversely to the change in heart rate (HR). There was a significant positive correlation between V(d) and percent HR change. These data provide evidence that preterm infants have measurable activity of bronchiolar β₂ receptor responsive to salbutamol.