AN ANALYSIS OF THE DURATION OF FENTANYL AND ITS METABOLITES IN URINE AND SALIVA

This study was undertaken to determine if metabolites of fentanyl migh t be useful in the detection and monitoring of substance abuse. The pr esence of fentanyl and two of its metabolites in the urine and saliva of seven female patients receiving small doses (110 +/- 56 mug) of fen tanyl was studied up to 96 h from the time of administration. Fentanyl and its two metabolites (norfentanyl and despropionylfentanyl) were e xtracted from samples and analyzed by gas chromatography/mass spectrom etry. Unchanged fentanyl was detectable in urine in all patients immed iately postoperatively and in 3 of 7 patients at 24 h. By 72 h, fentan yl was undetectable. Norfentanyl was present in larger quantities than fentanyl immediately postoperatively nd was detected in all patients at 48 h and in 4 of 7 patients at 96 h. Despropionylfentanyl was not d etected in any of the urine specimens tested. Neither fentanyl nor its metabolites could be detected consistently at any time in saliva. Sal iva testing does not appear to be a viable alternative to urine testin g based on this study. Urinary norfentanyl might be considered as the substance of choice when testing for fentanyl abuse.