Toxicological Investigation of a Case Series Involving the Synthetic Cathinone α-Pyrrolidinohexiophenone (α-PHP) and Identification of Phase I and II Metabolites in Human Urine.

α-Pyrrolidinohexiophenone (α-PHP) is a derivative of the class of α-pyrrolidinophenones, a subgroup of synthetic cathinones. These substances are the second most abused drugs of new psychoactive substances. Here, we report the toxicological investigation of a series of 29 authentic forensic and clinical cases with analytically confirmed intake of α-PHP including two cases of drug testing in newborns using meconium. The age range of subjects where serum samples were available was 23 - 51 years (median 39.5) and 90% were male. Serum α-PHP concentrations, determined by a validated LC-MS/MS method, showed a high variability ranging from 1 - 83 ng/mL (mean 40 ng/mL, median 36 ng/mL). Comprehensive toxicological analysis revealed co-consumption of other psychotropic drugs in almost all cases with frequent occurrence of opiates (60%), benzodiazepines (35%), cannabinoids (30%), and cocaine (20%). Hence, forensic and clinical symptoms like aggressive behaviour, sweating, delayed physical response and impaired balance could not be explained by the abuse of α-PHP alone but rather by poly-intoxications. Liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) and gas chromatography-mass spectrometry (GC-MS) were used to investigate the metabolism of α-PHP in vivo using authentic human urine samples. Altogether, 11 phase I metabolites and five phase II glucuronides could be identified by this approach. Apart from the parent drug, most abundant findings in urine were the metabolites dihydroxy-pyrrolidinyl-α-PHP, dihydro-α-PHP and to a lesser extent, 2'-oxo-dihydro-α-PHP and 2'-oxo-α-PHP. Monitoring of these metabolites along with the parent drug in forensic and clinical toxicology could unambiguously prove the abuse of the novel designer drug α-PHP.