Comparison of clinical effects and pharmacokinetics of once-daily Uniphyl and twice-daily Theo-Dur in asthmatic patients.
A pharmacokinetic study using theophylline syrup in adult asthmatic patients demonstrated a mean apparent volume of distribution of 0.38 liters/kg, mean elimination rate constant of 0.10 hours-1, and variable rates of clearance of theophylline (total body clearance of 0.38 to 0.96 ml/kg per minute). Subsequently, the asthmatic patients were compared using a cross-over design after maintenance Uniphyl (once daily at 8 a.m. or at 8 p.m.) and Theo-Dur (twice daily at 8 a.m. and 8 p.m.). Total daily maintenance theophylline dosage, calculated from the pharmacokinetic data, was identical in all three cross-over phases. At the end of each phase, plasma theophylline levels were measured every two hours and spirometric determinations were made every four hours (excluding 4 a.m.) for 24 hours. The following results were observed: highest peak and mean plasma theophylline concentration and area under the concentration-time curves with evening Uniphyl (p less than 0.05); prolonged time-to-peak theophylline concentration after nocturnal compared with daytime dosing; diurnal variation in pulmonary function and plasma theophylline concentrations; no significant differences between the three maintenance treatments in asthmatic symptoms or spirometric results.
D000328:Adult; D005260:Female; D005541:Forced Expiratory Volume; D006801:Humans; D007408:Intestinal Absorption; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D010366:Peak Expiratory Flow Rate; D013806:Theophylline / Q000008:administration & dosage* / Q000378:metabolism; D014797:Vital Capacity
D013806:Theophylline