Intoxications involving the fentanyl analogs acetylfentanyl, 4-methoxybutyrfentanyl and furanylfentanyl: results from the Swedish STRIDA project.

BACKGROUND: Potent and potentially harmful new psychoactive substances (NPS) are continuously introduced on the recreational drugs market. This report from the Swedish STRIDA project describes analytically confirmed cases of intoxication involving the fentanyl analogs acetylfentanyl, 4-methoxybutyrfentanyl, and furanylfentanyl.
METHODS: Patients with suspected NPS exposure presenting in emergency departments and intensive care units in Sweden and requiring hospital care are invited to the STRIDA project. Toxicological analysis of serum and urine samples was performed by multi-component liquid chromatographic-mass spectrometric methods. Data on clinical features were retrieved from telephone consultations with the Swedish Poisons Information Centre and from medical records.
RESULTS: Between April and November 2015, 14 analytically confirmed intoxications involving acetylfentanyl (nine cases), 4-methoxybutyrfentanyl (3), furanylfentanyl (1), and 4-methoxybutyrfentanyl together with furanylfentanyl (1) were identified. The patients were aged 20-40 (mean 28.5) years and 86% were men. Twelve patients (86%) were admitted to intensive care, where two required intubation and mechanical ventilation. Typical clinical features were decreased consciousness, respiratory depression, and miosis. In eight cases, the antidote naloxone was administered to counter the effects. The serum acetylfentanyl concentration (N = 7) was 0.6-51.6 (mean 18.3 and median 14.8) ng/mL, and in urine (N = 8) 0.1-686 (mean 155 and median 66.6) ng/mmol creatinine. The serum 4-methoxybutyrfentanyl concentration (N = 2) was 1.3 and 3.1 ng/mL, and 5.1-51.3 ng/mmol creatinine in urine (N = 3). For furanylfentanyl, the serum concentrations were 4.4 and 148 ng/mL and in urine 9.2 and 85 ng/mmol creatinine, respectively. In 13 cases (93%), other NPS and/or classical drugs were also detected. Drug products brought to hospital by patients contained acetylfentanyl (nasal spray and pink tablet), 4-methoxybutyrfentanyl (green tablet), furanylfentanyl/traces of 4-methoxybutyrfentanyl (nasal spray), and 4-fluorobutyrfentanyl (purple tablet).
CONCLUSION: Potentially life-threatening opioid toxicity was seen in acute intoxications involving acetylfentanyl, 4-methoxybutyrfentanyl, and furanylfentanyl. Intensive care treatment for one month was necessary in one acetylfentanyl case and one acetylfentanyl patient died from cerebral hemorrhage.