title: Temporal variations in trough serum theophylline concentrations at steady state.
abstract: Temporal variations in serum theophylline concentrations were observed in 14 healthy volunteers receiving multiple doses of theophylline. After repeated oral doses (6.9--18.2 mg/kg/day) of theophylline as either a nonalcoholic aminophylline solution or a controlled-release capsule, trough theophylline levels at steady state were significantly higher (p less than 0.05) in the morning than in the afternoon or evening. With the solution, the mean (+/-SE) trough serum level at 7 am was 11.1 +/- 0.9 micrograms/ml, and at 1 pm it was 9.6 +/- 0.8 micrograms/ml. With the capsule, the mean (+/-SE) trough serum level at 8 am was 13.8 +/- 0.9 micrograms/ml, and at 8 pm it was 10.7 +/- 0.9 micrograms/ml. Temporal variations in serum theophylline concentrations have not been reported previously and may be important in therapeutic monitoring.
mesh_terms: D000328:Adult; D000628:Aminophylline / Q000378:metabolism; D003692:Delayed-Action Preparations; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D013806:Theophylline / Q000008:administration & dosage / Q000097:blood*; D013997:Time Factors
chemical_list: D003692:Delayed-Action Preparations; D000628:Aminophylline; D013806:Theophylline