General practice theophylline audit in the Exeter Health District.

The serum theophylline concentration was determined in 150 asthmatic patients who received treatment from General Practitioners in the Exeter Health District. The serum theophylline concentration was below the therapeutic range in 75% of the patients evaluated. There was no correlation between serum concentration and daily dose, even when the latter was calculated with respect to bodyweight or body surface area. It was concluded that a theophylline Therapeutic Drug Monitoring (TDM) service should be available for general practice patients.