Serum theophylline levels of 10-20 jg/ml are considered to be necessary for maximum therapeutic effect (Turner-Warwick, 1957;Nicholson and Chick, 1973;Mitenko and Ogilvie, 1973) and when the upper limit of this range is exceeded, toxic symptoms occur with increasing frequency (Zwillich et al., 1975).Because the half-life of theophylline in serum can vary by up to sevenfold in different individuals (Ellis et al., 1976), measurement of serum theophylline is necessary to individualise treatment regimens. A method for rapid measurement on small blood samples would clearly be an advantage both in the outpatient management of asthmatic children and in the treatment of status asthmaticus when aminophylline is used. We report our experience over 9 months using a high-pressure liquid chromatograph to monitor serum theophylline concentration of asthmatic children attending this hospital.

No abstract