Pharmacokinetic properties of 4-fluoroamphetamine in serum and oral fluid after oral ingestion

INTRODUCTION: Each year, synthetic drugs are occurring in high numbers in the illicit drug market. But data on their pharmacology and toxicology are scarcely available. Therefore, a controlled study was performed to evaluate pharmacokinetic parameters of 4-fluoroamphetamine (4FA) in humans and to compare it with its effects.

METHODS: Twelve subjects ingested 100 mg and 5 subjects also received 150 mg 4-FA in a bitter lemon drink. Blood and oral fluid samples were taken during the following 12 hours and analyzed for 4-FA and traces of amphetamine as impurity by liquid chromatography-mass spectrometry (LC-MSMS).

RESULTS: During 12 hours after ingestion the concentration-time course of 4-FA was similar to that of amphetamine with maximal concentrations appearing in serum after about 2 hours (in median 195 ng/ml after the 100 mg dose, range 155-316 ng/ml). The elimination half-life was approximately 8-9 hours and shorter than that of amphetamine but exhibited a marked variation (5.5 - 16.8 hours). In oral fluid 4-FA could also be detected for 12 hours and concentrations were higher than in serum. During the first 3 hours after ingestion concentrations were higher most probably due to oral contamination. Serum concentrations in forensic cases were in the range of those observed in the present study suggesting dosages in recreational use in the range of those tested here.

CONCLUSIONS: The pharmacokinetic properties of 4-FA are similar to that of amphetamine including a marked variation in elimination. However, recreational dosages may already exhibit prominent adverse effects and may even have life-threatening consequences.