Serum concentration of aminophylline after rectal, oral and intravenous administration

Steady state serum concentrations of aminophylline were determined in 8 patients on each of 3 maintenance treatment schedules; suppositories, tablets and an alcholic elixir, totaling 16.5 mg/kg/day. Suppositories yielded subtherapeutic and highly variable concentrations (3.2±3.1 mcg/ml), tablets low therapeutic concentrations (7.1±1.9 mcg/ml) and the elixir, high therapeutic concentrations (16.8±3.8 mcg/ml). An intravenous aminophylline bolus of 4.5 mg/kg resulted in therapeutic concentrations when given during tablet therapy and in toxic concentrations when given during elixir therapy (12.3-13.5 and 21.6-23.1 mcg/ml, respectively). Aminophylline suppositories are efficacious. To maintain therapeutic serum aminophylline concentrations, the approximate daily dosages of tablets is 20-25 mg/kg/day, and as the alcohoic elixir 15 mg/kg/day. The dosage of intravenous aminophylline should be based on prior maintenance aminophylline therapy. When given following elixir treatment, the intravenous dose should not exceed 3 mg/kg.