Clinical use of polyethylene glycols as marker substances and determination in urine by liquid chromatography.

Adulteration of samples is a serious problem in the analysis of drugs of abuse. One of the most frequent methods is substitution of urines by "clean" urines to gain false-negative results in laboratory tests for drugs of abuse. One way to approach this problem may be to label the patient's urine with marker substances which are given orally prior to the delivery of urine. This concept is based on methods for determining malabsorption in pediatric medicine. We report a protocol for evaluating low-molecular-mass polyethylene glycols as enteral labelling marker substances. For monitoring renal excretion of the ingested polyethylene glycols we have developed and optimised an isocratic reversed-phase high-performance liquid chromatographic method with automatic sample cleanup by column switching in the back-flush technique and with RI detection. The chromatographic procedure is simple, reliable and rapid, allowing a high sample throughput for routine screening.

Urine labeling with orally applied marker substances in drug substitution therapy.

The compliance of 581 drug addicts attending six methadone substitution outpatient clinics was determined over a period of 18 months. Urine from these patients was labeled following oral administration of low molecular weight polyethylene glycols as marker substances. These substances were measured in approx. 5800 urine samples. A protocol for applying marker substances and ways to prevent substitution of urine samples were evaluated. Normal values for marker substances in urine were determined. The results suggest that this labeling procedure is a new diagnostic tool to prevent manipulation of urine samples by drug addicts receiving substitution therapy.