Description of MPHP
Firstly, 4′-Methyl-α-pyrrolidinohexiophenone (MPHP) is a stimulant compound which has been reported as a novel designer drug. It is closely related to pyrovalerone, being simply its chain-lengthened homologue. In the pyrrolidinophenone series, stimulant activity is maintained so long as the positions of the aryl, ketone and pyrrolidinyl groups are held constant. While the alkyl backbone can be varied anywhere between three and as many as seven carbons. With highest potency usually seen with the pentyl or isohexyl backbone. And a variety of substituents are tolerated on the aromatic ring.
History and Overview of the product .
The new designer drug 4′-methyl-α-pyrrolidinohexanophenone is a synthetic cathinone classified as an α-pyrrolidionophenone derivative . MPHP was first identified in seized products as a drug of abuse in Germany in 2000. In Japan, it has been detected in many types of seized products including mixed dried plants called “herbs”. Powder-type products called “bath salts,” and liquid-type products called “liquid aroma” because it was first identified in distributed illegal products in 201.
Use and Metabolism of MPHP
It is presumed to exhibit stimulant effects and serious toxicity like other synthetic cathinones and amphetamines. There is only one report on acute poisoning with toxic liver damage and rhabdomyolysis after its intake . In this poisoning case, MPHP was found at a concentration of 100 ng/mL in the patient’s serum by gas chromatography–mass spectrometry (GC–MS). While it could not be detected in urine because of its metabolism , which is consistent with the findings in a study on MPHP metabolites in rat urine .
It could not be found in rat urine 24 h after administration with either 1 mg/kg. Which corresponds to the common dose of abusers, or 20 mg/kg by GC–MS with a limit of detection of 100 ng/mL . Conversely, the main urinary MPHP metabolite 4′-carboxy-α-pyrrolidinohexanophenone (4′-carboxy-PHP) could be detected in both human and rat urine after drug administration.
Therefore, to date, the toxicological detection of MPHP in urine by GC–MS seems to be possible only via its metabolites. Including 4′-carboxy-PHP. But these compounds are not commercially available . Recently, Minakata et al. reported that a matrix-assisted laser desorption ionization-quadrupole time-of-flight-mass spectrometry enabled the sensitive quantification of MPHP. With a range of 2–100 ng/mL. Although the samples used consisted of blood from volunteers with MPHP added as a reference. In the present study, we are the first to identify and quantify MPHP in human postmortem urine by using liquid chromatography–time-of-flight-mass spectrometry (LC–TOF-MS) in an autopsy case.