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Clemastine, also known as meclastin, is an antihistamine and anticholinergic.^[1] Unlike loratadine or fexofenadine, clemastine is a sedating antihistamine, however it exhibits fewer other side effects than most of the widely used antihistamines.^{[citation needed]} Clemastine is also classified as an antipruritic (i.e., it stops itching).

Indications

Clemastine is indicated for use in treating allergic rhinitis, such as sneezing, rhinorrhea, pruritus and lacrimation.^{[medical citation needed]}

Side effects

Overdosage symptoms are paradoxical, ranging from CNS depression to stimulation. Stimulation is most common in children, and is usually followed by excitement, hallucinations, ataxia, incoordination, muscle twitching, athetosis, hyperthermia, cyanosis convulsions, tremors, and hyperreflexia. This may be followed by postictal depression and cardiovascular/respiratory arrest. Other common overdose symptoms include dry mouth, fixed dilated pupils, flushing of the face, and pyrexia. In adults, overdose usually leads to CNS depression, ranging from drowsiness to coma.^{[medical citation needed]}

Pharmacology

Clemastine is an antihistamine with anticholinergic and sedative effects. Antihistamines competitively bind to histamine receptor sites, thus reducing the neurotransmitter's effects. Effects of histamine (which are countered by antihistamines) include:

Increased capillary permeability
Increased capillary dilatation
Edema (i.e., swelling)
Pruritus (Itch)
Gastrointestinal/respiratory smooth muscle constriction

Clemastine inhibits both the vasoconstrictor and vasodilator effects of histamine. Depending on the dose, the drug can produce paradoxical effects, including CNS stimulation or depression.

Most antihistamines exhibit some type of anticholinergic activity. Antihistamines act by competitively binding to H1- receptor sites, thus blocking the binding endogenous histamine. Antihistamines do not chemically inactivate or prevent the normal release of histamine.

Clemastine does also act as FIASMA (functional inhibitor of acid sphingomyelinase).^[2]

Clemastine is rapidly absorbed from the gastrointestinal tract and peak plasma concentrations are attained in 2-4 hours. Antihistamines are thought to be metabolized in the liver, mostly by mono-/didemethylation and glucuronide conjugation. It is an inhibitor of cytochrome P450 2D6 and may interfere with other drugs metabolized by this isozyme.

Mechanism of action

Clemastine is a selective histamine H1 antagonist. It binds to the histamine H1 receptor, thus blocking the action of endogenous histamine, which leads to temporary relief of the negative symptoms caused by histamine.^{[medical citation needed]}

Society and culture

Clemastine is an OTC drug, and is available under many names and dosage forms worldwide. ^[3]

References

^ Anon., GB 942152 (1963).
^ Kornhuber J, Muehlbacher M, Trapp S, Pechmann S, Friedl A, Reichel M, Mühle C, Terfloth L, Groemer T, Spitzer G, Liedl K, Gulbins E, Tripal P (2011). "Identification of novel functional inhibitors of acid sphingomyelinase". PLoS ONE 6 (8): e23852. doi:10.1371/journal.pone.0023852. PMC 3166082. PMID 21909365.
^ drugs.com Clemastine at drugs.com international listings Page accessed May 10, 2015

External links

NIH Medline Plus listing on Clemastine
The pharmacokinetics and bioavailability of clemastine and phenylpropanolamine in single-component and combination formulations

UpToDate Contents

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1. 授乳中の薬剤使用の原則 principles of medication use during lactation
2. 成人における亜急性および慢性咳嗽の治療 treatment of subacute and chronic cough in adults
3. 患者情報：アレルギー性鼻炎（季節性アレルギー）（詳細） allergic rhinitis seasonal allergies beyond the basics
4. 患者情報：成人における慢性咳嗽（詳細） chronic cough in adults beyond the basics

English Journal

Utility of 4-chloro-7-nitrobenzofurazan (NBD-CI) for the Spectrophotometric and spectrofluorometric determination of several antihistamine and antihypertensive drugs.

Abd el-HS1, Colyer CL, Hassan WS, Shalaby A.
Journal of AOAC International.J AOAC Int.2013 Sep-Oct;96(5):968-75.
New, sensitive, and selective spectrophotometric and spectrofluorometric methods have been developed for determination of clemastine hydrogen fumarate (Clem), loratadine (Lor), losartan potassium (Los), and ramipril (Ram) in both pure form and pharmaceutical formulations using 4-chloro-7-nitrobenzof
PMID 24282933

The antihistamines clemastine and desloratadine inhibit STAT3 and c-Myc activities and induce apoptosis in cutaneous T-cell lymphoma cell lines.

Döbbeling U1, Waeckerle-Men Y, Zabel F, Graf N, Kündig TM, Johansen P.
Experimental dermatology.Exp Dermatol.2013 Feb;22(2):119-24. doi: 10.1111/exd.12086.
Mycosis fungoides and its leukaemic counterpart Sézary syndrome are the most frequent cutaneous T-cell lymphomas (CTCL), and there is no cure for these diseases. We evaluated the effect of clinically approved antihistamines on the growth of CTCL cell lines. CTCL cell lines as well as blood lymphocy
PMID 23362870

Identification and determination of selected histamine antagonists by densitometric method.

Czerwińska K1, Wyszomirska E, Mazurek AP.
Acta poloniae pharmaceutica.Acta Pol Pharm.2013 Jan-Feb;70(1):19-26.
The conditions for identification were determined for four histamine antagonists: clemastine fumarate, loratadine, cetirizine dihydrochloride and desloratadine by TLC (thin-layer chromatography) method. The selected chromatographic conditions were used to develop a densitometric method for the conte
PMID 23610955

Japanese Journal

High-performance liquid chromatographic-tandem mass spectrometric method for the determination of clemastine in human plasma

HORVATH Viola,TOLOKAN Antal,EGRESI Andrea,PAP Timea,HORVAI George,BALOGH-NEMES Katalin,KLEBOVICH Imre
Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 816(1), 153-159, 2005-02
NAID 10016804266

ヒスタミンと抗ヒスタミン薬の油水界面におけるイオン移動ボルタンメトリー

塚本龍治,楠文代
分析化学 52(10), 865-871, 2003-10-05
ニトロベンゼン/水の油水界面のイオン移動ボルタンメトリーによって,ヒスタミン及び抗ヒスタミン薬であるdl-クロルフェニラミン,クレマスチン,ジフェンヒドラミン,シプロヘプタジン,メクリジン,プロメタジン,ケトチフェン及びテルフェナジンの油水界面におけるイオン移動と吸着を検討した.ボルタモグラム上に,抗ヒスタミン薬はヒスタミンに比べ負電位側で水相から油相への移動による陽極波が現れ,また,電気毛管曲線 …
NAID 110002907429

Related Pictures

★リンクテーブル★

リンク元	「クレマスチン」
拡張検索	「clemastine fumarate」

「クレマスチン」

Clemastine
Systematic (IUPAC) name
	(2R)-2-{2-[(1R)-1-(4-chlorophenyl)-1-phenylethoxy]ethyl}-1-methylpyrrolidine
Clinical data
AHFS/Drugs.com	monograph
MedlinePlus	a682542
Pregnancy; category	B (USA);
Legal status	Unscheduled;; OTC;
Routes of; administration	Oral
Pharmacokinetic data
Bioavailability	39.2%
Metabolism	Hepatic
Biological half-life	21.3 Hours
Excretion	Renal
Identifiers
CAS Registry Number	15686-51-8
ATC code	D04AA14 R06AA04
PubChem	CID: 26987
IUPHAR/BPS	6063
DrugBank	DB00283
ChemSpider	25129
UNII	95QN29S1ID
KEGG	D03535
ChEBI	CHEBI:3738
ChEMBL	CHEMBL1626
Chemical data
Formula	C21H26ClNO
Molecular mass	343.9 g/mol
	SMILES Clc1ccc(cc1)[C@](OCC[C@@H]2N(C)CCC2)(c3ccccc3)C ;
	InChI InChI=1S/C21H26ClNO/c1-21(17-7-4-3-5-8-17,18-10-12-19(22)13-11-18)24-16-14-20-9-6-15-23(20)2/h3-5,7-8,10-13,20H,6,9,14-16H2,1-2H3/t20-,21-/m1/s1 ; Key:YNNUSGIPVFPVBX-NHCUHLMSSA-N ;
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