IMMUNOASSAY EVIDENCE FOR FENTANYL IN HAIR OF SURGERY PATIENTS

Head hair samples obtained from surgery patients who received fentanyl during anesthesia were analyzed by immunoassay for the presence of fe ntanyl. Thirteen hair samples were collected from patients following i ntravenous administration of 1-6 mg of fentanyl. Additional hair sampl es were collected following the administration of 0.18 and 0.38 mg of sufentanil to 2 patients. The elapsed time after drug administration f or all patients ranged from 7 to 273 days. Twenty control hair samples also were collected from staff members who reported no surgery or ane sthesia during the previous year. All samples were initially washed wi th methanol, followed by extraction with methanol and reconstitution i n citrate buffer. Analysis of wash and extract fractions was performed by radioimmunoassay (Coat-A-Count Fentanyl assay). Segmental analysis was performed on the surgery patients' hair samples. Eight of the fen tanyl patients' hair samples contained fentanyl concentrations (equiva lents) of 0.13-0.48 ng/10 mg of hair in the 'root' end. Fentanyl conce ntrations in the 'tip' segment were lower than those found in the 'roo t' segment with the exception of 1 subject whose hair sample had been collected only 7 days after surgery. The remaining 5 patients had fent anyl concentrations similar to those determined for the control subjec ts hair samples (0-0.08 ng/10 mg, n = 19): No correlation between hair fentanyl concentration and administered dose was found for the 13 fen tanyl subjects. Both sufentanil subjects' hair samples tested negative . One control subject who had experienced environmental exposure to fe ntanyl had a fentanyl concentration of 0.29 ng/10 mg in the extract an d 0.63 ng/10 mg in the wash fraction. Overall, it was concluded that h air analysis for fentanyl provided convincing evidence of past exposur e to the drug.