Theophylline pharmacokinetics: variations between two similar study populations using oral oxtriphylline syrup.

The pharmacokinetics of two unmatched populations of asthmatic children, one from an asthmatic convalescent center in Denver and the other from an urban outpatient clinic, are compared after single and repeated dosing of a new asthma formulation, oxtriphylline syrup. Significant differences (p less than 0.05) in populations' theophylline total body clearance, apparent volume of distribution and absorption rates suggest future studies of multiple center design representing patterns of asthma more typical to the population at large would be more appropriate for selection of theophylline dosage guidelines.