Comparison study of sustained-release theophylline products: Slo-bid capsules versus Theo-Dur tablets in 20 children and young adults with asthma.

Because there are few published studies on capsulized sustained-release theophylline (SRT) products in children, we compared Slo-bid capsules to Theo-Dur tablets in a group of school age children and young adults with asthma in an 8-week randomized crossover study design with patients maintaining daily symptom diary cards and peak expiratory flow rates. Theophylline levels were obtained at 8 hours after the morning dose on day 7, 14, and 28 of each study period. Data were analyzed by one-way analysis of variance, regression equation, and Student's t test. Both products were demonstrated to have grossly similar absorption characteristics and efficacy at 12-hour intervals in the age group studied. Average daily dose requirement was 717 mg/day. Considerable week-to-week intrapatient variation in 8-hour theophylline levels was noted in both products, implying that precise dose adjustments cannot be made from a given level. Our literature review reveals the need for more data to support the current widespread practice of dosing children less than 8 years of age at 12-hour intervals. A retrospective review of ingestion before and after breakfast revealed no variation between the seven patients ingesting SRT before breakfast compared to 13 patients routinely ingesting SRT after a typical childhood breakfast.