In vitro reaction of formaldehyde with fenfluramine: conversion to N-methyl fenfluramine

Embalming is common, and it can create problems for the forensic scientist if a drug has been the cause death and this drug is also reactive toward the embalming fluid. Previous studies have focused on the tricyclic amines nortriptyline and desipramine. In the presence of formaldehyde, a typical component of embalming fluid, either of these two compounds can be rapidly converted to their methylated derivatives amitriptyline and imipramine, respectively. We have begun a larger project designed to determine the reactivity and reactions of a wide range of drugs with formaldehyde. We report here our results from fenfluramine, which, like the tricyclic amines, is reactive towards formaldehyde and is converted into its N-methyl derivative. The rate of conversion is dependent upon pH and formaldehyde concentration. Up to 100% conversion in 24 h was observed. In addition, we have also devised a simplified procedure for monitoring this process that may be useful for others working in this area. Finally, we note that the reactions of fenfluramine studied here and of amines in general with formaldehyde need to be considered when performing postmortem/postembalming forensic analysis.