Title: Astemizole
CAS Registry Number: 68844-77-9
CAS Name: 1-[(4-Fluorophenyl)methyl]-N-[1-[2-(4-methoxyphenyl)ethyl]-4-piperidinyl]-1H-benzimidazol-2-amine
Additional Names: 1-(p-fluorobenzyl)-2-[[1-(p-methoxyphenethyl)-4-piperidyl]amino]benzimidazole
Manufacturers' Codes: R-43512
Trademarks: Astemisan (Zdravlje); Hismanal (Janssen); Histamen (Polifarma); Histaminos (Lesvi); Kelp (Omni); Laridal (Elfar-Drag); Metodik (Labinca); Novo-Nastizol A (Bago); Paralergin (Vita); Retolen (Byk Elmu); Waruzol (Farmanic)
Molecular Formula: C28H31FN4O
Molecular Weight: 458.57
Percent Composition: C 73.34%, H 6.81%, F 4.14%, N 12.22%, O 3.49%
Literature References: Nonsedating-type histamine H1-receptor antagonist. Prepn: F. Janssens et al., EP 5318; eidem, US 4219559 (1979, 1980 both to Janssen). Pharmacology: J. Van Wauwe et al., Arch. Int. Pharmacodyn. Ther. 251, 39 (1981); A. Wauquier, C. J. E. Niemegeers, Eur. J. Pharmacol. 72, 245 (1981). In vitro and in vivo binding characteristics: P. M. Laduron et al., Mol. Pharmacol. 21, 294 (1982). Effect on human psychomotor performance: T. Seppala, K. Savolainen, Curr. Ther. Res. 31, 638 (1982). Clinical study in treatment of hay fever: J. Callier et al., ibid. 29, 24 (1981). Mutagenicity study: P. Vanparys et al., Arch. Toxicol. 50, 167 (1982). Review of pharmacology and clinical trials: D. M. Richards et al., Drugs 28, 38-61 (1984). Comprehensive description: A. M. Al-Obaid, M. S. Mian, Anal. Profiles Drug Subs. 20, 173-208 (1991).
Properties: Crystals from 2,2¢-oxybispropane, mp 172.9°. Freely sol in organic solvents. Practically insol in water. uv max (ethanol): 219, 249, 286 nm (e 27250.229, 6480.293, 8634.280); (0.1N HCl): 209, 277 nm (e 57889.908, 18073.394).
Melting point: mp 172.9°
Absorption maximum: uv max (ethanol): 219, 249, 286 nm (e 27250.229, 6480.293, 8634.280)
Therap-Cat: Antihistaminic.
Keywords: Antihistaminic.
Asulam Atenolol Atevirdine Athamantin Atipamezole

Systematic (IUPAC) name
1-[(4-fluorophenyl)methyl]- N-[1-[2-(4-methoxyphenyl)ethyl]- 4-piperidyl]benzoimidazol-2-amine
Clinical data
AHFS/ Multum Consumer Information
MedlinePlus a600034
Pregnancy cat. C (USA)
Legal status Unscheduled
Routes Oral
Pharmacokinetic data
Bioavailability  ?
Metabolism Hepatic
Half-life 24 hours
Excretion Fecal
CAS number 68844-77-9 YesY
ATC code R06AX11
PubChem CID 2247
IUPHAR ligand 2603
DrugBank DB00637
ChemSpider 2160 YesY
UNII 7HU6337315 YesY
KEGG D00234 YesY
Chemical data
Formula C28H31FN4O 
Mol. mass 458.571 g/mol
 YesY (what is this?)  (verify)

Astemizole (R43512, marketed under the brand name Hismanal) was a second-generation antihistamine drug that has a long duration of action. Astemizole was discovered by Janssen Pharmaceutica in 1977. It has been withdrawn from the market in most countries because of rare but potentially fatal side effects (QTc interval prolongation and related arrhythmias due to hERG channel blockade).[1]