Development and clinical evaluation of a dried urine spot method for detection of morphine among opioid users

In recent years, drug testing in body fluids has gained popularity for validating self-reported drug use. The storage and transportation of urine specimens is a major concern for remote areas where the facilities for performing drug abuse testing are lacking.

The aim of the present study was to develop an efficient method for testing opiate in dried urine spots (DUS) and to evaluate its clinical applicability.

The methodology involved optimization of conditions for extraction, recovery, short-, and long-term stability (room temperature, 4°C,-20°C) for detection of opiate from dried urine spots. Further, the extraction efficiency from dried urine spots was compared with the conventional drug testing methodology. The screening was done by using enzyme-linked immunosorbent assay technique, and confirmation was achieved by gas chromatography equipped with nitrogen phosphorus detector.

Deionized water was found to be a suitable extracting solvent compare to bi-carbonate buffer (pH 9.2) and saline. Primary screening was achieved by 2 punches taken from a 20-μl (diameter 1.3 cm) spotted urine samples, whereas confirmation was achieved by 2 complete circles each of 20 μl sample volume. The recovery was found to be 99.41% in water. No sign of significant degradation was seen among all storage conditions.

In the current study, DUS has achieved the same level of precision and reproducibility as that of standard methods used for drug testing in urine. Hence, the DUS sampling appears to have potential to detect opiate among drug users in a clinical setting.