[Treatment with sustained theophylline release. Monitoring by salivary assay in children].

We have tested the possibility of replacing plasma assays by salivary assays of theophylline for the monitoring of sustained-release theophylline therapy in asthmatic children. In a first group of 40 children aged 7.2 +/- 3.3 years (mean +/- SD) treated with sustained-release theophylline in mean daily doses of 18.8 +/- 5 mg/kg, 77 plasma and saliva samples were taken simultaneously 6 hours after the morning dose (6 H). Saliva was collected after mouth-wash and stimulation with 10 mg of citric acid. Assays were performed using the EMIT method. Theophylline plasma concentrations (P) and salivary concentrations (S), both expressed as mumol/l, were found to correlate: P = 1.58 S + 8.7 (P less than 0.0001). In a second group of 33 children, 39 simultaneous samples were taken at 6 H. From the equation previously obtained the plasma concentration corresponding to each salivary concentration was calculated, and the calculated value was compared with the measured value. The difference between the two values was 7.1 +/- 9 mumol/l. On this basis, and because the method is non-invasive and painless, were are now using salivary assays (under strict conditions of collection and measurement) to verify the patients' compliance and to maintain or adjust dosage in asthmatic children.