The Case of the Disappearing Mephedrone
A suspected Driving While Intoxicated/Driving Under the Influence case is submitted to the laboratory and screened for alcohol and other drugs. AxSYM immunoassay results were negative, ethanol headspace gas chromatography/mass spectrometry (GC/MS) results were negative, and initial base GC/MS screening revealed a large peak at 9.69 of a 22 minute screening run. After multiple GC/MS library searches were conducted a hit for mephedrone was made.
Mephedrone, also known as 4-methyl-N-methylcathinone is a synthetic central nervous system stimulant structurally related to cathinone (active alkaloid found in the khat plant), 3,4- methylenedioxymethamphetamine (MDMA), methamphetamine, methcathinone and other schedule I phenethylamines.1 It is abused for the stimulants effects that are similar to those observed in users of MDMA or ecstasy, amphetamines or cocaine. Like other “designer drugs” mephedrone was available for sale on the internet and in head shops until it made its way to the Control Substance Act in 2010. Mephedrone has also been sold as MDMA and has led to a number of deaths and hospitalizations of users due to adverse effects or as a factor in their death. Some of the unintended side effects include dilated pupils, poor concentration, teeth grinding, problems focusing visually, poor short-term memory, hallucinations, delusions and erratic behavior.1
As this was one of the first mephedrone toxicology cases in this laboratory a new analytical method was needed. Analytical standards were ordered and following an already established procedure for amphetamines; method development and validation was commenced. Initial analysis by liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS) gave a negative value for mephedrone which did not correspond with the intensity of the peak seen on screening. Other analyst were recruited to rerun the sample by GC/MS as well as LC/MS/MS to rule out a possible mistake. Following similar repeat results, a stability study was conducted of mephedrone.2
Stability data were evaluated based on both matrix (whole blood, plasma, and urine) and storage temperature. When frozen, mephedrone in all three matrices were stable for the 14 day period of the experiment. At 4°C, whole blood samples lost approximately 30% of the initial concentration after seven days of storage and more than 50% of the initial concentration after 14 days of storage. Plasma samples decreased in concentration by approximately 10% after four days at 4°C and lost a total of 31% of the initial concentration after 14 days of storage. Urine samples remained stable when refrigerated up to 14 days. At room temperature, mephedrone specimens lost a significant portion of the initial concentration, regardless of matrix. In whole blood, more than 30% of the initial concentration was lost after one day and no drug was detectable by the seventh day. In plasma, over 90% of the initial concentration was lost by the fourth day. Urine was more stable, but after 14 days of storage, nearly 60% of the drug had been lost.2
The findings of this study reinforces the importance of proper storage of biological samples from transfer after collection to analysis.
1. Europol–EMCDDA Joint Report on a new psychoactive substance: 4-methylmethcathinone (mephedrone)”. European Monitoring Centre for Drugs and Drug Addiction. 27 May 2010. Retrieved 2013-03-29.
2. The Stability of Four Designer Drugs: MDPV, Mephedrone, BZP and TFMPP in Three Biological Matrices under Various Storage Conditions Robert D. Johnson; Sabra R. Botch-Jones Journal of Analytical Toxicology 2013; doi: 10.1093/jat/bks138 <http://jat.oxfordjournals.org/content/37/2/51.full?keytype=ref&ijkey=aDLxYXgHFtsW5Ng>