Adequacy of recommended aminophylline loading doses in children.

The adequacy of a loading dose of aminophylline 6 mg/kg i.v. in hospitalized pediatric patients with reactive airway disease was studied. Children six months to 14 years of age were studied to determine their serum theophylline concentrations after they were given an aminophylline loading dose of 5-7 mg/kg i.v. and to see whether they had to receive additional bolus doses. Bolus doses were infused over 20-30 minutes and were followed by a continuous infusion. Additional bolus doses were administered if the patient's serum theophylline concentration and clinical condition indicated they were necessary. Data from two separate phases of the study were combined for analysis. Phase 1 was designed for estimating population pharmacokinetic values. Some 72% of the 64 patients studied had subtherapeutic serum theophylline concentrations (< 10 mg/L) within 5.5 hours of the loading dose, and 78% required at least one additional bolus dose. Males had significantly lower serum theophylline concentrations than females; of the patients with subtherapeutic concentrations, 67% were males. Patients five years of age or younger were more likely than older children to have subtherapeutic theophylline concentrations. A 6-mg/kg loading dose of i.v. aminophylline did not produce adequate serum theophylline concentrations or eliminate the need for a second bolus dose in most pediatric patients with acute exacerbations of asthma.