Patient compliance with oral theophylline therapy

Day-to-day variations in plasma theophylline concentrations at steady-state have been assessed in 29 hospital inpatients who required theophylline for obstructive airways disease. Plasma concentrations were measured at 09.00h and 14.00h for four consecutive days in the equilibrium state in 13 patients taking 350 mg/day and 16 patients taking 700 mg/day. Analysis of variance gave 95% confidence limits for day-to-day variation of +/- 2.9 micrograms/ml at 350 mg/day and +/- 4.8 micrograms/ml at 700 mg/day. In a separate study, compliance with sustained-release theophylline therapy has been assessed in a group of 63 patients receiving the drug in general practice but not attending hospital. Compliance was estimated by comparing plasma theophylline concentrations before and after a 7-day period of measured theophylline consumption and by tablet counting. Of the 63 patients, 16 had discontinued their theophylline prior to being contacted and two did so during the first week: these were considered non-compliant. Three patients had plasma concentrations which increased by more than the day-to-day variation for their dose level during monitored intake and one other took less than 80% of his tablets. These patients were also considered non-compliant. A further four patients in whom plasma theophylline levels were zero on at least one occasion during the study were also adjudged non-compliant. Thus non-compliance with prescribed theophylline dosage occurred in 26 (41.3%) of the patients studied. In the majority of these, treatment had been discontinued and the non-compliance was gross.(ABSTRACT TRUNCATED AT 250 WORDS)