Experience of a laboratory service for drug screening in urine.

The use of a drug screening service has been investigated over a nine month period during which 1500 urine samples from 765 patients were analysed. Preliminary drug screening of urine samples was performed by EMIT immunoassays adapted for use on the Cobas Bio analyser; further identification and confirmation were carried out by Toxi-Lab thin-layer chromatography and capillary gas chromatography. A large number of positive results were obtained for benzodiazepines, cannabinoids, methadone and opiates (mainly dihydrocodeine). Only a limited number of urines gave positive results for amphetamine and related stimulants; cocaine metabolite was rarely detected in samples. The service proved to be of considerable value in the management of drug misusers, and for the identification of new substances taken by the local population.