LC-MS/MS analysis of pholedrine in a fatal intoxication case

Pholedrine (4'-hydroxymethamphetamine) is a cardiovascular agent exerting hypertensive and adrenergic effects. High doses may cause a drop in the peripheral circulation blood flow and increase blood pressure, heart rate and body temperature up to a state of central respiratory paralysis. A 15-year-old girl who suffered from heavy agitation and hallucinations was admitted to the intensive care unit in a comatose state. The clinical findings included a maximum heart rate of 170 bpm and a body temperature of 43.8 degrees C. Resuscitation measures were in vain and abandoned after approximately 2h. A toxicological emergency analysis using GC/MS revealed a considerable amount of pholedrine in blood and urine. A method for determining pholedrine in human body fluids utilizing high-performance liquid chromatography (HPLC)/tandem mass spectrometry (LC-MS/MS) with a turbo ion-spray source was developed, using D11-methamphetamine and D5-methylenedioxymethamphetamine as internal standards. Samples were prepared by SPE extraction using SPEC-C18AR/MP3((R)) columns, which yielded the best extraction recovery (67%). Chromatographic separation was achieved at pH 5 on an RP-18 stationary phase applying gradient elution from 50 to 70% of B (methanol/acetonitrile 3/1 (v/v), 0.02% acetic acid) in A (5mM ammonium acetate/acetonitrile 95/5 (v/v), 0.02% acetic acid). Supra-pure acetic acid was added to the post-column effluent with a flow rate of 0.2 microl/min to optimize ionization. Detection was carried out in the positive ionization, multiple reaction monitoring (MRM) mode. The chromatograms showed no interference from other substances. The limit of detection (LOD, S/N=3) of pholedrine was 0.8 ng/ml and its lower limit of quantification (LLOQ, S/N=10) 3ng/ml. The calibration curve was linear (r=0.999) in the range 1-100 ng/ml. Samples with higher concentrations were diluted to suit the working range. The intra-day R.S.D. between 5 and 80 ng/ml were 3.8-8.7% and the inter-day R.S.D. between 5 and 100 ng/ml were 6.7-10.7%. The pholedrine concentrations in blood and urine collected when the girl was still alive were 16.1 microg/ml (R.S.D. 10.5%) and 1120 microg/ml (R.S.D. 8%), respectively. In post-mortem samples, they were 23.0 microg/ml (R.S.D. 5.1%) in heart blood and 27.3 microg/g (R.S.D. 6.6%) in the liver.