3.2
© Springer-Verlag Berlin Heidelberg 2005
II.3.2 Butyrophenones
by Kazuo Igarashi
Introduction
Butyrophenone drugs including haloperidol are being widely used in the  eld of psychiatry.
 e acute butyrophenone poisoning incidents sometimes take place; in such cases, the analysis
of a butyrophenone becomes necessary in forensic toxicology or clinical toxicology.  eir 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 are
haloperidol and bromperidol, which most frequently cause poisoning incidents among butyro-
phenones.  ese drugs are rapidly metabolized in human bodies into reduced haloperidol and
reduced bromperidol, respectively. In this chapter, the methods of GC/MS, HPLC and LC/MS
a

are presented for analysis of haloperidol, bromperidol and their reduced forms.
Structures of butyrophenones.
⊡ Figure 2.1
264 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

v.
A er centrifugation at 600 g for 5 min, the upper organic layer is transferred to a small
glass test tube and evaporated to dryness.
vi.  e residue are dissolved in 20 µL ethanol.
265
vii. 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 method
 e butyrophenone drugs analyzable by GC or GC/MS in the underivatized forms are halo-
peridol, bromperidol, moperone and  oropipamide; but for timiperone and spiperone, satis-
factory peaks cannot be obtained.
TICs and SIM chromatograms of haloperidol, bromperidol and their reduced forms are
shown in
> Fig. 2.2.  e detection limit was about 10 pg in an injected volume for both halo-
peridol and bromperidol; the recoveries were also excellent.  e separation ability of GC or
GC/MS is much superior to that of HPLC or LC/MS.
HPLC and LC/MS analysis
Reagents and their preparation
 e sources for acquisition of haloperidol, bromperidol and their reduced forms is the same as
described in the GC/MS section.
TICs and SIM chromatograms by GC/MS for the authentic standards of butyrophenone drugs
(100 ng/mL each) (A) and for a serum extract from a poisoned patient (B). m/z 224: haloperidol
(HP) and reduced haloperidol (RHP); m/z 268: bromperidol (BP, IS) and reduced bromperidol (RBP).
⊡ Figure 2.2
HPLC and LC/MS analysis
266 Butyrophenones
HPLC analysis

(IS) obtained by HPLC-DAD.  e optimum detection wavelength was 220 nm; when meas-
ured at 250 nm, reduced haloperidol could not be detected.  e detection limit obtained by
HPLC-DAD was about 5 ng in an injected volume for all compounds.
HPLC-DAD is advantageous over HPLC-UV in that the sensitivity can be enhanced by
measuring a target compound at the wavelength of its absorbance maximum, or by shi ing the
267
wavelength from its maximum to avoid impurity peaks. Also by measuring an absorbance
spectrum of a compound, it is possible to make tentative identi cation.
By LC/MS analysis, the sensitivity and speci city are much higher. Distinct peaks of all
compounds appear (
> Fig. 2.4); the detection limit by LC/MS was about 2 pg in an injected
volume.
For sensitive analysis of timiperone and spiperone with relatively high molecular weights,
LC/MS may be most suitable.
Poisoning cases, and toxic and fatal concentrations
A 2-year plus 5 month-old female and an 11-month-old male [18] had ingested 265 mg
haloperidol in total (combined amount for both children); both were brought to a hospital in
the comatose state and showed bradycardia, hypotension and sinus arrhythmia. Mannitol was
injected into the female child intravenously; though the consciousness was gradually recovered
24 h a er admission, neurological symptoms, such as tremor, muscle sti ness and dyskinesia
of the face, appeared.  us, diphenhydramine was injected into her intravenously; she recov-
ered 4 days a er admission. For the male baby, similar treatments, such as intravenous injec-
tion of mannitol and diphenhydramine, were carried out, but the neurological symptoms were
not improved easily; it took as long as 7 days for his recovery.
 erapeutic and toxic blood levels of haloperidol were reported to be 5–40 and 50–100 ng/
mL, respectively; therapeutic blood levels of bromperidol 2–20 ng/mL [19].  erapeutic and
toxic blood levels of  oropipamide were reported to be 0.1–0.4 and 0.5–0.6 ng/mL, respec-
tively [20].
HPLC-DAD chromatograms for the authentic haloperidol (HP) and reduced haloperidol (RHP)
(100 ng/mL each) (A) and for a serum extract from a poisoned patient (B).