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2D Structure
Also known as: 52-86-8, Haldol, Serenace, Aloperidin, Eukystol, Aloperidol
Molecular Formula
C21H23ClFNO2
Molecular Weight
375.9  g/mol
InChI Key
LNEPOXFFQSENCJ-UHFFFAOYSA-N
FDA UNII
J6292F8L3D

A phenyl-piperidinyl-butyrophenone that is used primarily to treat SCHIZOPHRENIA and other PSYCHOSES. It is also used in schizoaffective disorder, DELUSIONAL DISORDERS, ballism, and TOURETTE SYNDROME (a drug of choice) and occasionally as adjunctive therapy in INTELLECTUAL DISABILITY and the chorea of HUNTINGTON DISEASE. It is a potent antiemetic and is used in the treatment of intractable HICCUPS. (From AMA Drug Evaluations Annual, 1994, p279)
Haloperidol is a Typical Antipsychotic.
1 2D Structure

2D Structure

2 Identification
2.1 Computed Descriptors
2.1.1 IUPAC Name
4-[4-(4-chlorophenyl)-4-hydroxypiperidin-1-yl]-1-(4-fluorophenyl)butan-1-one
2.1.2 InChI
InChI=1S/C21H23ClFNO2/c22-18-7-5-17(6-8-18)21(26)11-14-24(15-12-21)13-1-2-20(25)16-3-9-19(23)10-4-16/h3-10,26H,1-2,11-15H2
2.1.3 InChI Key
LNEPOXFFQSENCJ-UHFFFAOYSA-N
2.1.4 Canonical SMILES
C1CN(CCC1(C2=CC=C(C=C2)Cl)O)CCCC(=O)C3=CC=C(C=C3)F
2.2 Other Identifiers
2.2.1 UNII
J6292F8L3D
2.3 Synonyms
2.3.1 MeSH Synonyms

1. Haldol

2.3.2 Depositor-Supplied Synonyms

1. 52-86-8

2. Haldol

3. Serenace

4. Aloperidin

5. Eukystol

6. Aloperidol

7. Serenelfi

8. Brotopon

9. Serenase

10. Dozic

11. Linton

12. Einalon S

13. Aloperidolo

14. Galoperidol

15. Halojust

16. Halopoidol

17. Ulcolind

18. Uliolind

19. Halopal

20. Keselan

21. Mixidol

22. Pernox

23. Sernas

24. Sernel

25. Aldo

26. Lealgin Compositum

27. Bioperidolo

28. Sigaperidol

29. Peluces

30. 4-[4-(4-chlorophenyl)-4-hydroxypiperidin-1-yl]-1-(4-fluorophenyl)butan-1-one

31. Mcn-jr-1625

32. Haloperidolum

33. Aloperidon

34. 177716-59-5

35. R-1625

36. 4-(4-(4-chlorophenyl)-4-hydroxypiperidin-1-yl)-1-(4-fluorophenyl)butan-1-one

37. Nsc 170973

38. R 1625

39. 1-(3-p-fluorobenzoylpropyl)-4-p-chlorophenyl-4-hydroxypiperidine

40. Haloperidol (haldol)

41. 4'-fluoro-4-(4-(p-chlorophenyl)-4-hydroxypiperidinyl)butyrophenone

42. 4'-fluoro-4-(4-hydroxy-4-(4'-chlorophenyl)piperidino)butyrophenone

43. 4-[4-(4-chlorophenyl)-4-hydroxy-1-piperidinyl]-1-(4-fluorophenyl)-1-butanone

44. Chembl54

45. Haldol (tn)

46. Haldol Solutab

47. Nsc-170973

48. Nsc-615296

49. 4-(4-hydroxy-4'-chloro-4-phenylpiperidino)-4'-fluorobutyrophenone

50. 1-butanone, 4-(4-(4-chlorophenyl)-4-hydroxy-1-piperidinyl)-1-(4-fluorophenyl)-

51. 4-(4-(4-chlorophenyl)-4-hydroxy-1-piperidinyl)-1-(4-fluorophenyl)-1-butanone

52. Mls000028450

53. Chebi:5613

54. Fortunan

55. Halosten

56. 4-(4-(p-chlorophenyl)-4-hydroxypiperidino)-4'-fluorobutyrophenone

57. 4-[4-(p-chlorophenyl)-4-hydroxypiperidino]-4'-fluorobutyrophenone

58. J6292f8l3d

59. Butyrophenone, 4'-fluoro-4-(4-(p-chlorophenyl)-4-hydroxypiperidino)-

60. 1-butanone, 4-[4-(4-chlorophenyl)-4-hydroxy-1-piperidinyl]-1-(4-fluorophenyl)-

61. Nsc170973

62. Nsc615296

63. Cas-52-86-8

64. Ncgc00015500-10

65. Aloperidolo [dcit]

66. Halidol

67. Halopidol

68. Pekuces

69. Smr000058303

70. Halol

71. Aloperidolo [italian]

72. Poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene]

73. 4-(4-(para-chlorophenyl)-4-hydroxypiperidino)-4'-fluorobutyrophenone

74. Butyrophenone, 4-(4-(p-chlorophenyl)-4-hydroxypiperidino)-4'-fluoro-

75. Gamma-(4-(p-chlorophenyl)-4-hydroxypiperidino)-p-fluorobutyrophenone

76. 4-[4-(4-chlorophenyl)-4-hydroxy-1-piperidyl]-1-(4-fluorophenyl)-butan-1-one

77. Poly[[2-[(3,7-dimethyloctyl)oxy]-5-methoxy-1,4-phenylene]-1,2-ethenediyl]

78. Dsstox_cid_14150

79. Dsstox_rid_79117

80. Dsstox_gsid_34150

81. Haloperidolum [inn-latin]

82. Neurodol

83. Butyrophenone, 4-[4-(p-chlorophenyl)-4-hydroxypiperidino]-4'-fluoro-

84. Gamma-(4-(p-chlorophenyl)-4-hydroxpiperidino)-p-fluorbutyrophenone

85. Ccris 1630

86. Hsdb 3093

87. Sr-01000003076

88. Einecs 200-155-6

89. Nsc 615296

90. Brn 0331267

91. Duraperidol

92. Unii-j6292f8l3d

93. Epoxy Resins

94. 4'-fluoro-4-[4-hydroxy-4-(4'-chlorophenyl)piperidino]butyrophenone

95. Gamma-[4-(p-chlorophenyl)-4-hydroxypiperidino]-p-fluorobutyrophenone

96. 4-[4-(para-chlorophenyl)-4-hydroxypiperidino]-4'-fluorobutyrophenone

97. Picroside-iii

98. Haloperidol, 1

99. Haloperidol, Powder

100. Prestwick_250

101. N--boc-l-asparagine

102. Haloperidol [usan:usp:inn:ban:jan]

103. Spectrum_000861

104. Tocris-0931

105. Starbld0018801

106. Opera_id_446

107. 4'-fluoro-4-(4-hydroxy-4-p-chlorophenylpiperidino)butyrophenone

108. Haloperidol [mi]

109. 4-[4-(4-chloro-phenyl)-4-hydroxy-piperidin-1-yl]-1-(4-fluoro-phenyl)-butan-1-one;propionate(hcl)

110. 4-[4-(4-chlorophenyl)-4-hydroxypiperidino]-4'-fluorobutyrophenone

111. Gamma-(4-(p-chlorophenyl)-4-hydroxypiperidino)-p-fluorbutyrophenone

112. Prestwick0_000115

113. Prestwick1_000115

114. Prestwick2_000115

115. Prestwick3_000115

116. Spectrum2_001268

117. Spectrum3_000448

118. Spectrum4_000570

119. Spectrum5_000788

120. Haloperidol [inn]

121. Haloperidol [jan]

122. Lopac-h-1512

123. Haloperidol [hsdb]

124. Haloperidol [usan]

125. Biomol-nt_000035

126. Gtpl86

127. Probes1_000255

128. Probes2_000296

129. H 1512

130. Haloperidol [vandf]

131. Schembl8264

132. Haloperidol [mart.]

133. Lopac0_000583

134. Oprea1_509923

135. Bspbio_000130

136. Bspbio_002096

137. Haloperidol [usp-rs]

138. Haloperidol [who-dd]

139. Haloperidol [who-ip]

140. Kbiogr_000980

141. Kbiogr_002390

142. Kbioss_001341

143. Kbioss_002395

144. 5-21-02-00377 (beilstein Handbook Reference)

145. Mls001146904

146. Bidd:gt0128

147. Divk1c_000654

148. Spectrum1500325

149. Haloperidol-[chlorophenyl-d4]

150. Spbio_001236

151. Spbio_002069

152. Mcm-jr-1625

153. Bpbio1_000144

154. Bpbio1_001231

155. Haloperidol (jp17/usp/inn)

156. Dtxsid4034150

157. Bdbm21398

158. Hms502a16

159. Kbio1_000654

160. Kbio2_001341

161. Kbio2_002390

162. Kbio2_003909

163. Kbio2_004958

164. Kbio2_006477

165. Kbio2_007526

166. Kbio3_001316

167. Kbio3_002869

168. Lnepoxffqsencj-uhfffaoysa-

169. Haloperidol [orange Book]

170. Cmap_000037

171. Haloperidol For System Suitability

172. Ninds_000654

173. Ac250

174. Haloperidol [ep Monograph]

175. Haloperidol [usp Impurity]

176. Haloperidol For Peak Identification

177. Hms1568g12

178. Hms1920d03

179. Hms2089m15

180. Hms2091j09

181. Hms2095g12

182. Hms2234p08

183. Hms3261f08

184. Hms3370h11

185. Hms3657i13

186. Hms3712g12

187. Pharmakon1600-01500325

188. Zinc537822

189. Haloperidol [usp Monograph]

190. Bcp33202

191. Cha71659

192. Haloperidol 1.0 Mg/ml In Methanol

193. Str04750

194. Tox21_110162

195. Tox21_300475

196. Tox21_500583

197. A0h334

198. Ccg-36042

199. Ccg-39111

200. Haloperidolum [who-ip Latin]

201. Nsc757054

202. Stl417208

203. Vesalium Component Haloperidol

204. 4-[4-(4-chlorophenyl)-4-hydroxy-1-piperidyl]-1-(4-fluorophenyl)butan-1-one

205. Akos000280660

206. Tox21_110162_1

207. At13670

208. Cs-1971

209. Db00502

210. Lp00583

211. Nsc-757054

212. Sdccgsbi-0050565.p005

213. Haloperidol Component Of Vesalium

214. Idi1_000654

215. Mrf-0000027

216. Qtl1_000042

217. Wln: T6ntj A3vr Df& Dq Dr Dg

218. Ncgc00015500-01

219. Ncgc00015500-02

220. Ncgc00015500-03

221. Ncgc00015500-04

222. Ncgc00015500-05

223. Ncgc00015500-06

224. Ncgc00015500-07

225. Ncgc00015500-08

226. Ncgc00015500-09

227. Ncgc00015500-11

228. Ncgc00015500-12

229. Ncgc00015500-13

230. Ncgc00015500-14

231. Ncgc00015500-15

232. Ncgc00015500-16

233. Ncgc00015500-17

234. Ncgc00015500-19

235. Ncgc00015500-24

236. Ncgc00015500-32

237. Ncgc00016234-01

238. Ncgc00023875-02

239. Ncgc00023875-04

240. Ncgc00023875-05

241. Ncgc00023875-06

242. Ncgc00023875-07

243. Ncgc00023875-08

244. Ncgc00023875-09

245. Ncgc00254503-01

246. Ncgc00261268-01

247. Ac-19691

248. Bh166165

249. Hy-14538

250. Sbi-0050565.p004

251. Haloperidol Decanoate Impurity, Haloperidol-

252. Sc 170973

253. Ab00052008

254. Eu-0100583

255. Ft-0669100

256. Ft-0669101

257. Ft-0697842

258. H0912

259. N1910

260. S1920

261. Sw196557-4

262. C01814

263. D00136

264. Vu0239704-10

265. Ab00052008-21

266. Ab00052008-22

267. Ab00052008_23

268. Ab00052008_24

269. A899749

270. L000288

271. Q251347

272. Sr-01000003076-2

273. Sr-01000003076-8

274. W-105791

275. Brd-k67783091-001-04-8

276. Brd-k67783091-001-05-5

277. Brd-k67783091-003-03-6

278. Haloperidol Decanoate Impurity G [ep Impurity]

279. Sr-01000003076-11

280. Haloperidol, European Pharmacopoeia (ep) Reference Standard

281. .gamma.-[4-(p-chlorphenyl)-4-hydroxpiperidino]-p-fluorbutyrophenone

282. Haloperidol Decanoate Impurity, Haloperidol- [usp Impurity]

283. Haloperidol, United States Pharmacopeia (usp) Reference Standard

284. .gamma.-(4-(p-chlorophenyl)-4-hydroxpiperidino)-p-fluorbutyrophenone

285. Haloperidol, Pharmaceutical Secondary Standard; Certified Reference Material

286. 4-[4-(4-chlorophenyl)-4-hydroxy-1-piperidinyl]-1-(4-fluorophenyl) -1-butanone

287. Haloperidol For Peak Identification, European Pharmacopoeia (ep) Reference Standard

288. Haloperidol For System Suitability, European Pharmacopoeia (ep) Reference Standard

289. Haloperidol Solution, 1.0 Mg/ml In Methanol, Ampule Of 1 Ml, Certified Reference Material

2.4 Create Date
2005-03-25
3 Chemical and Physical Properties
Molecular Weight 375.9 g/mol
Molecular Formula C21H23ClFNO2
XLogP33.2
Hydrogen Bond Donor Count1
Hydrogen Bond Acceptor Count4
Rotatable Bond Count6
Exact Mass375.1401348 g/mol
Monoisotopic Mass375.1401348 g/mol
Topological Polar Surface Area40.5 Ų
Heavy Atom Count26
Formal Charge0
Complexity451
Isotope Atom Count0
Defined Atom Stereocenter Count0
Undefined Atom Stereocenter Count0
Defined Bond Stereocenter Count0
Undefined Bond Stereocenter Count0
Covalently Bonded Unit Count1
4 Drug and Medication Information
4.1 Drug Information
1 of 4  
Drug NameHaldol
PubMed HealthHaloperidol Decanoate (Injection)
Drug ClassesAntipsychotic
Drug LabelHaloperidol is the first of the butyrophenone series of major antipsychotics. The chemical designation is 4-[4-(p-chlorophenyl)-4-hydroxypiperidino]-4'-fluorobutyrophenone and it has the following structural formula:HALDOL (haloperidol) is available.
Active IngredientHaloperidol decanoate; Haloperidol lactate
Dosage FormInjectable
RouteInjection
Strengtheq 50mg base/ml; eq 5mg base/ml; eq 100mg base/ml
Market StatusPrescription
CompanyJanssen Pharms

2 of 4  
Drug NameHaloperidol
PubMed HealthHaloperidol
Drug ClassesAntipsychotic
Drug LabelHaloperidol is the first of the butyrophenone series of major tranquilizers. The chemical designation is 4-[4-(p-chloro-phenyl)-4-hydroxypiperidino]-4fluorobutyrophenone and it has the following structural formula:C21H23ClFNO2 375.87Haloperidol...
Active IngredientHaloperidol; Haloperidol lactate
Dosage FormTablet; Concentrate; Injectable
Routeinjection; oral; Injection; Oral
Strength0.5mg; 1mg; eq 2mg base/ml; eq 5mg base/ml; 5mg; 5mg in 10ml vials; 2mg; 10mg; 20mg
Market StatusPrescription
CompanySilarx; Gland Pharma; Pharm Assoc; Teva Pharms Usa; Sandoz; Teva Pharms; Fresenius Kabi Usa; Eurohlth Intl; Sagent Pharms; Zydus Pharms Usa; Agila Speclts; Mylan

3 of 4  
Drug NameHaldol
PubMed HealthHaloperidol Decanoate (Injection)
Drug ClassesAntipsychotic
Drug LabelHaloperidol is the first of the butyrophenone series of major antipsychotics. The chemical designation is 4-[4-(p-chlorophenyl)-4-hydroxypiperidino]-4'-fluorobutyrophenone and it has the following structural formula:HALDOL (haloperidol) is available.
Active IngredientHaloperidol decanoate; Haloperidol lactate
Dosage FormInjectable
RouteInjection
Strengtheq 50mg base/ml; eq 5mg base/ml; eq 100mg base/ml
Market StatusPrescription
CompanyJanssen Pharms

4 of 4  
Drug NameHaloperidol
PubMed HealthHaloperidol
Drug ClassesAntipsychotic
Drug LabelHaloperidol is the first of the butyrophenone series of major tranquilizers. The chemical designation is 4-[4-(p-chloro-phenyl)-4-hydroxypiperidino]-4fluorobutyrophenone and it has the following structural formula:C21H23ClFNO2 375.87Haloperidol...
Active IngredientHaloperidol; Haloperidol lactate
Dosage FormTablet; Concentrate; Injectable
Routeinjection; oral; Injection; Oral
Strength0.5mg; 1mg; eq 2mg base/ml; eq 5mg base/ml; 5mg; 5mg in 10ml vials; 2mg; 10mg; 20mg
Market StatusPrescription
CompanySilarx; Gland Pharma; Pharm Assoc; Teva Pharms Usa; Sandoz; Teva Pharms; Fresenius Kabi Usa; Eurohlth Intl; Sagent Pharms; Zydus Pharms Usa; Agila Speclts; Mylan

4.2 Therapeutic Uses

Anti-Dyskinesia Agents; Antiemetics; Antipsychotic Agents, Butyrophenone; Dopamine Antagonists

National Library of Medicine's Medical Subject Headings online file (MeSH, 1999)


Haloperidol is indicated for the management of the manifestations of acute and chronic psychotic disorders including schizophrenia, manic states, and drug-induced psychoses, such as steroid psychosis. It may also be useful in the management of aggressive and agitated patients, including patients with organic mental syndrome or mental retardation. Haloperidol decanoate, a long-acting parenteral from, is intended for maintenance use in the management of patients requiring prolonged parenteral therapy, as in chronic schizophrenia. /Included in US product labeling/

MICROMEDEX Thomson Health Care. USPDI - Drug Information for the Health Care Professional. 23rd ed. Volume 1. MICROMEDEX Thomson Health Care, Greenwood Village, CO. 2003. Content Reviewed and Approved by the U.S. Pharmacopeial Convention, Inc., p. 1456


Haloperidol is effective in the treatment of children with severe behavior problems of apparently unprovoked, combative, explosive hyperexcitability. It is also effective in the short-term treatment of hyperactivity in children who show excessive motor activity with accompanying conduct disorders such as aggressiveness, impulsiveness, easy frustration, short attention span, and/or rapid mood fluctuations. In these two groups of children, haloperidol should be tried only in patients who fail to respond to psychotherapy or other non-neuroleptic medication. /Included in US product labeling/

MICROMEDEX Thomson Health Care. USPDI - Drug Information for the Health Care Professional. 23rd ed. Volume 1. MICROMEDEX Thomson Health Care, Greenwood Village, CO. 2003. Content Reviewed and Approved by the U.S. Pharmacopeial Convention, Inc., p. 1456


Haloperidol is used to control tics and vocalizations of Tourette's syndrome in children and adults. /Included in US product labeling/

MICROMEDEX Thomson Health Care. USPDI - Drug Information for the Health Care Professional. 23rd ed. Volume 1. MICROMEDEX Thomson Health Care, Greenwood Village, CO. 2003. Content Reviewed and Approved by the U.S. Pharmacopeial Convention, Inc., p. 1456


For more Therapeutic Uses (Complete) data for HALOPERIDOL (8 total), please visit the HSDB record page.


4.3 Drug Warning

Pregnancy risk category: C /RISK CANNOT BE RULED OUT. Adequate, well controlled human studies are lacking, and animal studies have shown risk to the fetus or are lacking as well. There is a chance of fetal harm if the drug is given during pregnancy; but the potential benefits may outweigh the potential risk./

Physicians Desk Reference. 58th ed. Thomson PDR. Montvale, NJ 2004., p. 2444


Extrapyramidal reactions occur frequently with haloperidol, especially during the first few days of therapy. In most patients, these reactions consist of parkinsonian symptoms (e.g., marked drowsiness and lethargy, drooling or hypersalivation, fixed stare), which are mild to moderate in severity and are usually reversible following discontinuance of the drug. Other adverse neuromuscular reactions have been reported less frequently, but are often more severe, and include feelings of motor restlessness (i.e., akathisia), tardive dystonia, and dystonic reactions (e.g., hyperreflexia, opisthotonos, oculogyric crisis, torticollis, trismus).

McEvoy, G.K. (ed.). American Hospital Formulary Service - Drug Information 2003. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2003 (Plus Supplements)., p. 2289


Possible drowsiness or dizziness; caution when driving, using machinery, or doing things requiring alertness. Possible dizziness or lightheadedness; caution when getting up suddenly from a lying or sitting position.

MICROMEDEX Thomson Health Care. USPDI - Drug Information for the Health Care Professional. 23rd ed. Volume 1. MICROMEDEX Thomson Health Care, Greenwood Village, CO. 2003. Content Reviewed and Approved by the U.S. Pharmacopeial Convention, Inc., p. 1459


Because of the possibility of transient hypotension and/or precipitation of angina, haloperidol should be used with caution in patients with severe cardiovascular disorders. If hypotension occurs, metaraminol, norepinephrine, or phenylephrine may be used; epinephrine should not be used since haloperidol causes a reversal of epinephrine's vasopressor effects and a further lowering of blood pressure.

McEvoy, G.K. (ed.). American Hospital Formulary Service - Drug Information 2003. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2003 (Plus Supplements)., p. 2290


For more Drug Warnings (Complete) data for HALOPERIDOL (24 total), please visit the HSDB record page.


4.4 Drug Indication

Haloperidol is indicated for a number of conditions including for the treatment of schizophrenia, for the manifestations of psychotic disorders, for the control of tics and vocal utterances of Tourettes Disorder in children and adults, for treatment of severe behavior problems in children of combative, explosive hyperexcitability (which cannot be accounted for by immediate provocation). Haloperidol is also indicated in the short-term treatment of hyperactive children who show excessive motor activity with accompanying conduct disorders consisting of some or all of the following symptoms: impulsivity, difficulty sustaining attention, aggressivity, mood lability, and poor frustration tolerance. Haloperidol should be reserved for these two groups of children only after failure to respond to psychotherapy or medications other than antipsychotics.


FDA Label


5 Pharmacology and Biochemistry
5.1 Pharmacology

Use of the first-generation antipsychotics (including haloperidol) is considered highly effective for the management of the "positive" symptoms of schizophrenia including hallucinations, hearing voices, aggression/hostility, disorganized speech, and psychomotor agitation. However, this class is limited by the development of movement disorders such as drug-induced parkinsonism, akathisia, dystonia, and tardive dyskinesia, and other side effects including sedation, weight gain, and prolactin changes. Compared to the lower-potency first-generation antipsychotics such as [DB00477], [DB01624], [DB00623], and [DB01403], haloperidol typically demonstrates the least amount of side effects within class, but demonstrates a stronger disposition for causing extrapyramidal symptoms (EPS). Lowpotency medications have a lower affinity for dopamine receptors so that a higher dose is required to effectively treat symptoms of schizophrenia. In addition, they block many receptors other than the primary target (dopamine receptors), such as cholinergic or histaminergic receptors, resulting in a higher incidence of side effects such as sedation, weight gain, and hypotension. The balance between the wanted drug effects on psychotic symptoms and unwanted side effects are largely at play within dopaminergic brain pathways affected by haloperidol. Cortical dopamine-D2-pathways play an important role in regulating these effects and include the nigrostriatal pathway, which is responsible for causing extrapyramidal symptoms (EPS), the mesolimbic and mesocortical pathways, which are responsible for the improvement in positive schizophrenic symptoms, and the tuberoinfundibular dopamine pathway, which is responsible for hyperprolactinemia. A syndrome consisting of potentially irreversible, involuntary, dyskinetic movements may develop in patients. Although the prevalence of the syndrome appears to be highest among the elderly, especially elderly women, it is impossible to rely upon prevalence estimates to predict, at the inception of antipsychotic treatment, which patients are likely to develop the syndrome. Cases of sudden death, QT-prolongation, and Torsades de Pointes have been reported in patients receiving haloperidol. Higher than recommended doses of any formulation and intravenous administration of haloperidol appear to be associated with a higher risk of QT-prolongation and Torsades de Pointes. Although cases have been reported even in the absence of predisposing factors, particular caution is advised in treating patients with other QT-prolonging conditions (including electrolyte imbalance [particularly hypokalemia and hypomagnesemia], drugs known to prolong QT, underlying cardiac abnormalities, hypothyroidism, and familial long QT-syndrome). A potentially fatal symptom complex sometimes referred to as Neuroleptic Malignant Syndrome (NMS) has been reported in association with antipsychotic drugs. Clinical manifestations of NMS are hyperpyrexia, muscle rigidity, altered mental status (including catatonic signs) and evidence of autonomic instability (irregular pulse or blood pressure, tachycardia, diaphoresis, and cardiac dysrhythmias). Additional signs may include elevated creatine phosphokinase, myoglobinuria (rhabdomyolysis) and acute renal failure.


5.2 MeSH Pharmacological Classification

Anti-Dyskinesia Agents

Drugs used in the treatment of movement disorders. Most of these act centrally on dopaminergic or cholinergic systems. Among the most important clinically are those used for the treatment of Parkinson disease (ANTIPARKINSON AGENTS) and those for the tardive dyskinesias. (See all compounds classified as Anti-Dyskinesia Agents.)


Antipsychotic Agents

Agents that control agitated psychotic behavior, alleviate acute psychotic states, reduce psychotic symptoms, and exert a quieting effect. They are used in SCHIZOPHRENIA; senile dementia; transient psychosis following surgery; or MYOCARDIAL INFARCTION; etc. These drugs are often referred to as neuroleptics alluding to the tendency to produce neurological side effects, but not all antipsychotics are likely to produce such effects. Many of these drugs may also be effective against nausea, emesis, and pruritus. (See all compounds classified as Antipsychotic Agents.)


Dopamine Antagonists

Drugs that bind to but do not activate DOPAMINE RECEPTORS, thereby blocking the actions of dopamine or exogenous agonists. Many drugs used in the treatment of psychotic disorders (ANTIPSYCHOTIC AGENTS) are dopamine antagonists, although their therapeutic effects may be due to long-term adjustments of the brain rather than to the acute effects of blocking dopamine receptors. Dopamine antagonists have been used for several other clinical purposes including as ANTIEMETICS, in the treatment of Tourette syndrome, and for hiccup. Dopamine receptor blockade is associated with NEUROLEPTIC MALIGNANT SYNDROME. (See all compounds classified as Dopamine Antagonists.)


Antiemetics

Drugs used to prevent NAUSEA or VOMITING. (See all compounds classified as Antiemetics.)


5.3 FDA Pharmacological Classification
5.3.1 Active Moiety
HALOPERIDOL
5.3.2 FDA UNII
J6292F8L3D
5.3.3 Pharmacological Classes
Typical Antipsychotic [EPC]
5.4 ATC Code

N05AD01

S76 | LUXPHARMA | Pharmaceuticals Marketed in Luxembourg | Pharmaceuticals marketed in Luxembourg, as published by d'Gesondheetskeess (CNS, la caisse nationale de sante, www.cns.lu), mapped by name to structures using CompTox by R. Singh et al. (in prep.). List downloaded from https://cns.public.lu/en/legislations/textes-coordonnes/liste-med-comm.html. Dataset DOI:10.5281/zenodo.4587355


N - Nervous system

N05 - Psycholeptics

N05A - Antipsychotics

N05AD - Butyrophenone derivatives

N05AD01 - Haloperidol


5.5 Absorption, Distribution and Excretion

Absorption

Haloperidol is a highly lipophilic compound and is extensively metabolized in humans, which may cause a large interindividual variability in its pharmacokinetics. Studies have found a wide variance in pharmacokinetic values for orally administered haloperidol with 1.7-6.1 hours reported for time to peak plasma concentration (tmax), 14.5-36.7 hours reported for half-life (t12), and 43.73 g/Lh [range 14.89-120.96 g/Lh] reported for AUC. Haloperidol is well-absorbed from the gastrointestinal tract when ingested orally, however, the first-pass hepatic metabolism decreases its oral bioavailability to 40 - 75%. After intramuscular administration, the time to peak plasma concentration (tmax) is 20 minutes in healthy individuals or 33.8 minutes in patients with schizophrenia, with a mean half-life of 20.7 hours. Bioavailability following intramuscular administration is higher than that for oral administration. Administration of haloperidol decanoate (the depot form of haloperidol for long-term treatment) in sesame oil results in slow release of the drug for long-term effects. The plasma concentrations of haloperidol gradually rise, reaching its peak concentration at about 6 days after the injection, with an apparent half-life of about 21 days. Steady-state plasma concentrations are achieved after the third or fourth dose.


Route of Elimination

In radiolabeling studies, approximately 30% of the radioactivity is excreted in the urine following a single oral administration of 14C-labelled haloperidol, while 18% is excreted in the urine as haloperidol glucuronide, demonstrating that haloperidol glucuronide is a major metabolite in the urine as well as in plasma in humans.


Volume of Distribution

The apparent volume of distribution was found to range from 9.5-21.7 L/kg. This high volume of distribution is in accordance with its lipophilicity, which also suggests free movement through various tissues including the blood-brain barrier.


Clearance

Following intravenous administration, the plasma or serum clearance (CL) was found to be 0.39-0.708 L/h/kg (6.5 to 11.8 ml/min/kg). Following oral administration, clearance was found to be 141.65 L/h (range 41.34 to 335.80 L/h). Haloperidol clearance after extravascular administration ranges from 0.9-1.5 l/h/kg, however this rate is reduced in poor metabolizers of C_YP2D6_ enzyme. Reduced CYP2D6 enzyme activity may result in increased concentrations of haloperidol. The inter-subject variability (coefficient of variation, %) in haloperidol clearance was estimated to be 44% in a population pharmacokinetic analysis in patients with schizophrenia. Genetic polymorphism of CYP2D6 has been demonstrated to be an important source of inter-patient variability in the pharmacokinetics of haloperidol and may affect therapeutic response and incidence of adverse effects.


Haloperidol is well absorbed from the gastrointestinal tract but first-pass hepatic metabolism decreases oral bioavailability to 40 to 75%. Serum concentration peaks 0.5 to 4 hours after an oral dose.

Ellenhorn, M.J., S. Schonwald, G. Ordog, J. Wasserberger. Ellenhorn's Medical Toxicology: Diagnosis and Treatment of Human Poisoning. 2nd ed. Baltimore, MD: Williams and Wilkins, 1997., p. 674


The apparent volume of distribution is about 20 L/kg, consistent with the high lipophilicity of the drug. Haloperidol circulates in blood bound predominantly (90-94%) to plasma proteins.

Ellenhorn, M.J., S. Schonwald, G. Ordog, J. Wasserberger. Ellenhorn's Medical Toxicology: Diagnosis and Treatment of Human Poisoning. 2nd ed. Baltimore, MD: Williams and Wilkins, 1997., p. 674


Following administration of haloperidol in animals, the drug is distributed mainly into the liver, with lower concentrations being distributed into the brain, lung, kidneys, spleen, and heart. ... Haloperidol is about 92% bound to plasma proteins.

McEvoy, G.K. (ed.). American Hospital Formulary Service - Drug Information 2003. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2003 (Plus Supplements)., p. 2291


5.6 Metabolism/Metabolites

Haloperidol is extensively metabolised in the liver with only about 1% of the administered dose excreted unchanged in urine. In humans, haloperidol is biotransformed to various metabolites, including p-fluorobenzoylpropionic acid, 4-(4-chlorophenyl)-4-hydroxypiperidine, reduced haloperidol, pyridinium metabolites, and haloperidol glucuronide. In psychiatric patients treated regularly with haloperidol, the concentration of haloperidol glucuronide in plasma is the highest among the metabolites, followed, in rank order, by unchanged haloperidol, reduced haloperidol and reduced haloperidol glucuronide. The drug is thought to be metabolized primarily by oxidative N-dealkylation of the piperidine nitrogen to form fluorophenylcarbonic acids and piperidine metabolites (which appear to be inactive), and by reduction of the butyrophenone carbonyl to the carbinol, forming _hydroxyhaloperidol_. The enzymes involved in the biotransformation of haloperidol include cytochrome P450 (CYP) including CYP3A4 and CYP2D6, carbonyl reductase and uridine di-phosphoglucose glucuronosyltransferase enzymes. The greatest proportion of the intrinsic hepatic clearance of haloperidol is performed by glucuronidation and followed by the reduction of haloperidol to reduced haloperidol and by CYP-mediated oxidation. In studies of cytochrome-mediated disposition in vitro, CYP3A4 appears to be the major isoform of the enzyme responsible for the metabolism of haloperidol in humans. The intrinsic clearance of the back-oxidation of reduced haloperidol to the parent compound, oxidative N-dealkylation and pyridinium formation are of the same order of magnitude. This suggests that the same enzyme system is responsible for the above three metabolic reactions. In vivo human studies on haloperidol metabolism have shown that the glucuronidation of haloperidol accounts for 50 to 60% of haloperidol biotransformation and that approximately 23% of the biotransformation was accounted for by the reduction pathway. The remaining 20 to 30% ofthe biotransformation of haloperidol would be via N-dealkylation and pyridinium formation.


Although the exact metabolic fate has not been clearly established, it appears that haloperidol is principally metabolized in the liver. The drug appears to be metabolized principally by oxidative N-dealkylation of the piperidine nitrogen to form fluorophenylcarbonic acids and piperidine metabolites (which appear to be inactive), and by reduction of the butyrophenone carbonyl to the carbinol, forming hydroxyhaloperidol. Limited data suggest that the reduced metabolite, hydroxyhaloperidol, has some pharmacologic activity, although its activity appears to be less than that of haloperidol. Urinary metabolites in rats include p-fluorophenaceturic acid, beta-p-fluorobenzoylpropionic acid, and several unidentified acids.

McEvoy, G.K. (ed.). American Hospital Formulary Service - Drug Information 2003. Bethesda, MD: American Society of Health-System Pharmacists, Inc. 2003 (Plus Supplements)., p. 2291


... it is metabolized via reduction to reduced haloperidol, which is biologically inactive. Different extents of enterohepatic recycling, and ethnic differences in metabolism, could also account for the observed variability in haloperidol disposition.

PMID:2689040 Froemming JS; Clin Pharmacokinet 17 (6): 396-423 (1989)


The enzymes involved in the biotransformation of haloperidol include cytochrome P450 (CYP), carbonyl reductase and uridine diphosphoglucose glucuronosyltransferase. The greatest proportion of the intrinsic hepatic clearance of haloperidol is by glucuronidation, followed by the reduction of haloperidol to reduced haloperidol and by CYP-mediated oxidation. In studies of CYP-mediated disposition in vitro, CYP3A4 appears to be the major isoform responsible for the metabolism of haloperidol in humans. The intrinsic clearances of the back-oxidation of reduced haloperidol to the parent compound, oxidative N-dealkylation and pyridinium formation are of the same order of magnitude, suggesting that the same enzyme system is responsible for the 3 reactions. Large variation in the catalytic activity was observed in the CYP-mediated reactions, whereas there appeared to be only small variations in the glucuronidation and carbonyl reduction pathways. Haloperidol is a substrate of CYP3A4 and an inhibitor, as well as a stimulator, of CYP2D6.

PMID:10628896 Kudo S, Ishizaki T; Clin Pharmacokinet 37 (6): 435-56 (1999)


... In vivo pharmacogenetic studies have indicated that the metabolism and disposition of haloperidol may be regulated by genetically determined polymorphic CYP2D6 activity. However, these findings appear to contradict those from studies in vitro with human liver microsomes and from studies of drug interactions in vivo. Interethnic and pharmacogenetic differences in haloperidol metabolism may explain these observations.

PMID:10628896 Kudo S, Ishizaki T; Clin Pharmacokinet 37 (6): 435-56 (1999)


Haloperidol has known human metabolites that include (2S,3S,4S,5R)-6-[4-(4-Chlorophenyl)-1-[4-(4-fluorophenyl)-4-oxobutyl]piperidin-4-yl]oxy-3,4,5-trihydroxyoxane-2-carboxylic acid, Haloperidol pyridinium, and p-Fluorobenzoylpropionic acid and 4-(4-chlorophenyl)-4-hydroxypiperidine.

Haloperidol is a known human metabolite of reduced_haloperidol.

S73 | METXBIODB | Metabolite Reaction Database from BioTransformer | DOI:10.5281/zenodo.4056560


5.7 Biological Half-Life

Following oral administration, the half-life was found to be 14.5-36.7 hours. Following intramuscular injection, mean half-life was found to be 20.7 hours.


10 MG Haloperidol IV and oral administration to healthy volunteers: serum T1/2 10-19 hr after IV and 12-38.3 hr after oral administration. Bioavailability in the order of 60%; distribution volume around 1300 L.

PMID:822989 Forsman A, Ohman R; Curr Ther Res Clin Exp 20 (Sep): 319-36 (1976)


Haloperidol, Elimination: Oral: 24 hours (range 12 to 37 hours). Intramuscular: 21 hours (range, 17 to 25 hours). Intravenous: 14 hours (range, 10 to 19 hours). Haloperidol decanoate, Elimination: Approximately 3 weeks (single or multiple doses).

MICROMEDEX Thomson Health Care. USPDI - Drug Information for the Health Care Professional. 23rd ed. Volume 1. MICROMEDEX Thomson Health Care, Greenwood Village, CO. 2003. Content Reviewed and Approved by the U.S. Pharmacopeial Convention, Inc., p. 1486


5.8 Mechanism of Action

While haloperidol has demonstrated pharmacologic activity at a number of receptors in the brain, it exerts its antipsychotic effect through its strong antagonism of the dopamine receptor (mainly D2), particularly within the mesolimbic and mesocortical systems of the brain. Schizophrenia is theorized to be caused by a hyperdopaminergic state within the limbic system of the brain. Dopamine-antagonizing medications such as haloperidol, therefore, are thought to improve psychotic symptoms by halting this over-production of dopamine. The optimal clinical efficacy of antipsychotics is associated with the blockade of approximately 60 % - 80 % of D2 receptors in the brain. While the exact mechanism is not entirely understood, haloperidol is known to inhibit the effects of dopamine and increase its turnover. Traditional antipsychotics, such as haloperidol, bind more tightly than dopamine itself to the dopamine D2 receptor, with dissociation constants that are lower than that for dopamine. It is believed that haloperidol competitively blocks post-synaptic dopamine (D2) receptors in the brain, eliminating dopamine neurotransmission and leading to the relief of delusions and hallucinations that are commonly associated with psychosis. It acts primarily on the D2-receptors and has some effect on 5-HT2 and 1-receptors, with negligible effects on dopamine D1-receptors. The drug also exerts some blockade of -adrenergic receptors of the autonomic system. Antagonistic activity regulated through dopamine D2 receptors in the chemoreceptive trigger zone (CTZ) of the brain renders its antiemetic activity. Of the three D2-like receptors, only the D2 receptor is blocked by antipsychotic drugs in direct relation to their clinical antipsychotic abilities. Clinical brain-imaging findings show that haloperidol remains tightly bound to D2 dopamine receptors in humans undergoing 2 positron emission tomography (PET) scans with a 24h pause in between scans. A common adverse effect of this drug is the development of extrapyramidal symptoms (EPS), due to this tight binding of haloperidol to the dopamine D2 receptor. Due to the risk of unpleasant and sometimes lifelong extrapyramidal symptoms, newer antipsychotic medications than haloperidol have been discovered and formulated. Rapid dissociation of drugs from dopamine D2 receptors is a plausible explanation for the improved EPS profile of atypical antipsychotics such as [DB00734]. This is also consistent with the theory of a lower affinity for D2 receptors for these drugs. As mentioned above, haloperidol binds tightly to the dopamine receptor, potentiating the risk of extrapyramidal symptoms, and therefore should only been used when necessary.


Haloperidol has less prominent autonomic effects than do other antipsychotic drugs. It has little anticholinergic activity ... it blocks activation of alpha receptors by sympathomimetic amines but is much less potent than chlorpromazine in this action.

Goodman, L.S., and A. Gilman. (eds.) The Pharmacological Basis of Therapeutics. 5th ed. New York: Macmillan Publishing Co., Inc., 1975., p. 166


Although the complex mechanism of the therapeutic effect is not clearly established, haloperidol is known to produce a selective effect on the central nervous system (CNS) by competitive blockade of postsynaptic dopamine (D2) receptors in the mesolimbic dopaminergic system and an increased turnover of brain dopamine to produce its tranquilizing effects. With subchronic therapy, depolarization blockade, or diminished firing rate of the dopamine neuron (decreased release) along with D2 postsynaptic blockade results in the antipsychotic action.

MICROMEDEX Thomson Health Care. USPDI - Drug Information for the Health Care Professional. 23rd ed. Volume 1. MICROMEDEX Thomson Health Care, Greenwood Village, CO. 2003. Content Reviewed and Approved by the U.S. Pharmacopeial Convention, Inc., p. 1456