Drugs and Poisons in Humans - A Handbook of Practical Analysis (Part 28)

Introduction:Butyrophenone drugs including haloperidol are being widely used in the field of psychiatry. The acute butyrophenone poisoning incidents sometimes take place; in such cases, the analysis of a butyrophenone becomes necessary in forensic toxicology or clinical toxicology. Their analysis is being made by GC [1–4], GC/MS [5–6], HPLC [7–15] and LC/MS [16,17]. Six butyrophenones are now available as ethical drugs in Japan ( Fig. 2.1); the most typical ones are haloperidol and bromperidol, which most frequently cause poisoning incidents among butyrophenones. These drugs are rapidly metabolized in human bodies into reduced haloperidol and reduced bromperidol, respectively. In this...
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Drugs and Poisons in Humans - A Handbook of Practical Analysis (Part 28) 3.2II.3.2 Butyrophenones by Kazuo IgarashiIntroductionButyrophenone drugs including haloperidol are being widely used in the field of psychiatry.The acute butyrophenone poisoning incidents sometimes take place; in such cases, the analysisof a butyrophenone becomes necessary in forensic toxicology or clinical toxicology. Their anal-ysis is being made by GC [1–4], GC/MS [5–6], HPLC [7–15] and LC/MS [16,17]. Six butyro-phenones are now available as ethical drugs in Japan ( > Fig. 2.1); the most typical ones arehaloperidol and bromperidol, which most frequently cause poisoning incidents among butyro-phenones. These drugs are rapidly metabolized in human bodies into reduced haloperidol andreduced bromperidol, respectively. In this chapter, the methods of GC/MS, HPLC and LC/MSaare presented for analysis of haloperidol, bromperidol and their reduced forms.⊡ Figure 2.1Structures of butyrophenones.© Springer-Verlag Berlin Heidelberg 2005264 Butyrophenones GC/MS analysis Reagents and their preparation • Haloperidol can be purchased from Sigma (St. Louis, MO, USA) and other manufacturers; bromperidol, reduced haloperidol and reduced bromperidol from Research Biochemical International (Natick, MA, USA). • A 4-g aliquot of NaOH and 6 g NaCl are dissolved in distilled water to prepare 100 mL solution (1 M NaOH solution)b. • n-Hexane/isopropanol (95:5, v/v) mixture solution • 0.1 M Hydrochloric acid solution • As internal standard (IS)c, bromperidol (500 ng/mL in 0.1 M hydrochloric acid solution) is used for analysis of haloperidol, and vise versa. • Preparation of standard solutions: haloperidol or bromperidol solutions at 2–50 ng/mL in 0.01 M hydrochloric acid are prepared, and each 2-mL aliquot is placed in a 15-mL volume glass centrifuge tube with a ground-in stopper. GC/MS conditions Instrument: an Agilent 5890 GC instrument (Agilent Technologies, Palo Alto, CA, USA) con- nected with a JEOL Automass quadrupole mass spectrometer (JEOL, Tokyo, Japan). GC column: an HP-5 fused silica capillary column (30 m × 0.32 mm i. d., film thickness 0.25 µm, Agilent Technologies); column (oven) temperature: 100 °C (1 min) → 30 °C/min → 270 °C (30 s) → 5 °C/min → 290 °C (5 min); injection temperature: 260 °C; separator tempera- ture: 280 °C; carrier gas: He; its flow rate: 1.5 mL/min; MS ionization mode: EI; electron energy: 70 eV; detector voltage: 750 V; ion source temperature: 280 °C. Procedured i. A 2-mL volume of urine or blood, 0.05 mL IS and 0.5 mL of 1 M NaOH are placed in a 15-mL volume glass centrifuge tube with a ground-in stopper and mixed well, followed by addi- tion of 6 mL of the mixture of n-hexane/isopropanol and its shaking for 20 min. ii. After centrifugation at 600 g for 5 min, 5.5 mL of the upper organic layer is transferred to another 15-mL volume glass centrifuge tube, followed by the addition of 1.5 mL of 0.1 M hydrochloric acid solution and vigorous shaking for 20 min. iii. After centrifugation at 600 g for 5 min, the upper organic layer is discarded; the aqueous phase is again washed with 1 mL of the mixture of n-hexane/isopropanol by shaking it for 30 s. iv. After centrifugation at 600 g for 5 min, 1.2 mL of the lower aqueous phase is transferred to a 10-mL volume glass centrifuge tube with a ground-in stopper, followed by addition of 0.2 mL of 1 M NaOH and 1 mL of the n-hexane/isopropanol mixture, and vigorous shaking for 30 s. v. After centrifugation at 600 g for 5 min, the upper organic layer is transferred to a small glass test tube and evaporated to dryness. vi. The residue are dissolved in 20 µL ethanol. HPLC and LC/MS analysis 265vii. For quantitation, the selected ion monitoring (SIM) mode of GC/MS is employed using ions at m/z 224 for haloperidol and m/z 268 for bromperidol; peak area ratios of haloperi- dol or bromperidol to IS are plotted against various concentrations of the test compound spiked to blank blood or urine to draw a calibration curve. A peak area ratio of a test specimen is applied to the calibration curve to calculate its concentration.Assessment of the methodThe butyrophenone drugs analyzable by GC or GC/MS in the underivatized forms are halo-peridol, bromperidol, moperone and floropipamide; but for timiperone and spiperone, satis-factory peaks cannot be ob ...