Clemastine

Identification

Summary

Clemastine is an antihistamine with sedative and anticholinergic effects used to treat the symptoms of allergic rhinitis.

Brand Names

Wal-hist 12 Hr Relief

Generic Name

Clemastine

DrugBank Accession Number

DB00283

Background

An ethanolamine-derivative, first generation histamine H1 antagonist used in hay fever, rhinitis, allergic skin conditions, and pruritus. It causes drowsiness.

Type

Small Molecule

Groups

Approved, Investigational

Structure

Similar Structures

Weight: Average: 343.89
Monoisotopic: 343.170292166
Chemical Formula: C₂₁H₂₆ClNO

Synonyms

(+)-(2R)-2-(2-(((R)-p-chloro-α-methyl-α-phenylbenzyl)oxy)ethyl)-1-methylpyrrolidine
(+)-(2R)-2-[2-[[(R)-p-chloro-α-methyl-α-phenylbenzyl]oxy]ethyl]-1-methylpyrrolidine
Clemastina
Clemastine
Clemastinum

External IDs

HS-592

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Pharmacology

Indication

For the relief of symptoms associated with allergic rhinitis such as sneezing, rhinorrhea, pruritus and acrimation. Also for the management of mild, uncomplicated allergic skin manifestations of urticaria and angioedema. Used as self-medication for temporary relief of symptoms associated with the common cold.

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Associated Conditions

Indication Type	Indication	Combined Product Details	Approval Level	Dose Form
Symptomatic treatment of	Allergic rhinitis		••••••••••••
Treatment of	Allergic rhinitis		••••••••••••	•••••
Used in combination to manage	Allergic rhinitis	Combination Product in combination with: Phenylpropanolamine (DB00397)	••••••••••••
Symptomatic treatment of	Angioedema		••••••••••••
Symptomatic treatment of	Common cold		••• •••

Contraindications & Blackbox Warnings

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Pharmacodynamics

Clemastine is an antihistamine that also induces anticholinergic and sedative effects. Antihistamines competitively antagonize various physiological effects of histamine including increased capillary permeability and dilatation, the formation of edema, the "flare" and "itch" response, and gastrointestinal and respiratory smooth muscle constriction. Within the vascular tree, H1- receptor antagonists inhibit both the vasoconstrictor and vasodilator effects of histamine. Depending on the dose, H1- receptor antagonists can produce CNS stimulation or depression. Most antihistamines exhibit central and/or peripheral anticholinergic activity. Antihistamines act by competitively blocking H1- receptor sites. Antihistamines do not pharmacologically antagonize or chemically inactivate histamine, nor do they prevent the release of histamine.

Mechanism of action

Clemastine is a selective histamine H1 antagonist and binds to the histamine H1 receptor. This blocks the action of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms brought on by histamine.

Target	Actions	Organism
AHistamine H1 receptor	antagonist	Humans

Absorption

Rapidly absorbed from the gastrointestinal tract.

Volume of distribution

Not Available

Protein binding

Not Available

Metabolism

Antihistamines appear to be metabolized in the liver chiefly via mono- and didemethylation and glucuronide conjugation.

Route of elimination

Urinary excretion is the major mode of elimination.

Half-life

Not Available

Clearance

Not Available

Adverse Effects

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Toxicity

Oral LD₅₀ in rat and mouse is 3550 mg/kg and 730 mg/kg, respectively. Antihistamine overdosage reactions may vary from central nervous system depression to stimulation. In children, stimulation predominates initially in a syndrome which may include excitement, hallucinations, ataxia, incoordination, muscle twitching, athetosis, hyperthermia, cyanosis convulsions, tremors, and hyperreflexia followed by postictal depression and cardio-respiratory arrest. Convulsions in children may be preceded by mild depression. Dry mouth, fixed dilated pupils, flushing of the face, and fever are common. In adults, CNS depression, ranging from drowsiness to coma, is more common.

Pathways

Pathway	Category
Clemastine H1-Antihistamine Action	Drug action

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Not Available

Interactions

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This information should not be interpreted without the help of a healthcare provider. If you believe you are experiencing an interaction, contact a healthcare provider immediately. The absence of an interaction does not necessarily mean no interactions exist.

Drug	Interaction
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1,2-Benzodiazepine	The risk or severity of CNS depression can be increased when Clemastine is combined with 1,2-Benzodiazepine.
Acebutolol	The metabolism of Acebutolol can be decreased when combined with Clemastine.
Acetaminophen	The metabolism of Acetaminophen can be decreased when combined with Clemastine.
Acetazolamide	The risk or severity of CNS depression can be increased when Clemastine is combined with Acetazolamide.
Acetophenazine	The risk or severity of CNS depression can be increased when Clemastine is combined with Acetophenazine.

Food Interactions

Avoid alcohol.
Take with food.

Products

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Product Ingredients

Ingredient	UNII	CAS	InChI Key
Clemastine fumarate	19259EGQ3D	14976-57-9	PMGQWSIVQFOFOQ-YKVZVUFRSA-N

Product Images

International/Other Brands

Agasten (Novartis (Brazil)) / Allerhist-1 / Tavegil (Novartis) / Tavegyl (Novartis) / Tavist (Novartis) / Tavist-1 (Novartis)

Generic Prescription Products

Name	Dosage	Strength	Route	Labeller	Marketing Start	Marketing End
Clemastine Fumarate	Syrup	0.5 mg/1mL	Oral	Qualitest	1997-12-17	2012-02-22
Clemastine Fumarate	Tablet	2.68 mg/1	Oral	Northwind Pharmaceuticals	2014-04-28	Not applicable
Clemastine Fumarate	Tablet	2.68 mg/1	Oral	Teva Pharmaceuticals USA, Inc.	1992-04-01	Not applicable
Clemastine Fumarate	Tablet	2.68 mg/1	Oral	Sandoz	1993-10-31	2016-10-31
Clemastine Fumarate	Tablet	2.68 mg/1	Oral	Northwind Pharmaceuticals	2014-04-28	2014-06-25

Over the Counter Products

Name	Dosage	Strength	Route	Labeller	Marketing Start	Marketing End
Allergy Relief	Tablet	1.34 mg/1	Oral	CVS Health	1996-08-28	2014-03-21
Clemastine Fumarate	Tablet	1.34 mg/1	Oral	Sandoz	1993-10-31	2016-10-31
Clemastine Fumarate	Tablet	1.34 mg/1	Oral	Carilion Materials Management	1993-10-31	Not applicable
Clemastine Fumarate	Tablet	1.34 mg/1	Oral	Physicians Total Care, Inc.	2008-06-27	Not applicable
Dayhist Allergy	Tablet	1.34 mg/1	Oral	H.E.B.	1995-08-30	2016-12-16

Mixture Products

Name	Ingredients	Dosage	Route	Labeller	Marketing Start	Marketing End	Region	Image
Tavist-D Tablets	Clemastine fumarate (1 mg) + Phenylpropanolamine hydrochloride (75 mg)	Tablet, extended release	Oral	Novartis	1992-12-31	2001-04-24

Chemical Identifiers

UNII: 95QN29S1ID
CAS number: 15686-51-8
InChI Key: YNNUSGIPVFPVBX-NHCUHLMSSA-N
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
IUPAC Name: (2R)-2-{2-[1-(4-chlorophenyl)-1-phenylethoxy]ethyl}-1-methylpyrrolidine
SMILES: CN1CCC[C@@H]1CCO[C@](C)(C1=CC=CC=C1)C1=CC=C(Cl)C=C1

References

Synthesis Reference

British Patent 942,152; November 20,1963; assigned to Sandoz Ltd.

General References

Hayashi H, Okajima M, Yamada K: Atrial T (Ta) loop in dogs with or without atrial injury. Am Heart J. 1976 May;91(5):607-17. [Article]
Schran HF, Petryk L, Chang CT, O'Connor R, Gelbert MB: The pharmacokinetics and bioavailability of clemastine and phenylpropanolamine in single-component and combination formulations. J Clin Pharmacol. 1996 Oct;36(10):911-22. [Article]

External Links

Human Metabolome Database: HMDB0014428
KEGG Drug: D03535
KEGG Compound: C06913
PubChem Compound: 26987
PubChem Substance: 46506492
ChemSpider: 25129
BindingDB: 94606
RxNav: 2578
ChEBI: 3738
ChEMBL: CHEMBL1626
ZINC: ZINC000000402830
Therapeutic Targets Database: DAP000322
PharmGKB: PA164776997
RxList: RxList Drug Page
Drugs.com: Drugs.com Drug Page
Wikipedia: Clemastine

MSDS

Download (74.2 KB)

Clinical Trials

Clinical Trials Learn More" title="About Clinical Trials" id="clinical-trials-info" class="drug-info-popup" href="javascript:void(0);">

Phase	Status	Purpose	Conditions	Count
3	Recruiting	Treatment	Internuclear Ophthalmoplegia / Multiple Sclerosis	1
3	Recruiting	Treatment	Williams Syndrome	1
3	Unknown Status	Treatment	Allergic Reaction / Dermatitis	1
3	Withdrawn	Treatment	Dermatitis	1
2	Completed	Treatment	Chronic Urticaria	1

Pharmacoeconomics

Manufacturers

Actavis mid atlantic llc
Novex pharma
Silarx pharmaceuticals inc
Teva pharmaceuticals usa inc
Teva pharmaceuticals usa
Wockhardt eu operations (swiss) ag
Novartis pharmaceuticals corp
Perrigo co
Sandoz inc

Packagers

Apotex Inc.
Boca Pharmacal
CVS Pharmacy
Dispensing Solutions
H.J. Harkins Co. Inc.
Kroger Co.
Major Pharmaceuticals
Murfreesboro Pharmaceutical Nursing Supply
Novartis AG
Novex Pharma
Nucare Pharmaceuticals Inc.
Perrigo Co.
Pharmaceutical Utilization Management Program VA Inc.
Pharmedix
Physicians Total Care Inc.
Prescript Pharmaceuticals
Professional Co.
Qualitest
Sandoz
Silarx Pharmaceuticals
Teva Pharmaceutical Industries Ltd.
United Research Laboratories Inc.
Wockhardt Ltd.

Dosage Forms

Form	Route	Strength
Syrup	Oral	0.5 mg/1mL
Syrup	Oral	0.5 mg/5mL
Syrup	Oral	0.67 mg/5mL
Tablet	Oral	1.34 mg/1
Tablet	Oral	2.68 mg/1
Solution	Intramuscular; Intravenous	2 mg
Gel	Topical
Syrup	Oral
Tablet	Oral
Syrup	Oral	0.5 mg / 5 mL
Tablet	Oral	1 mg
Tablet, extended release	Oral

Prices

Unit description	Cost	Unit
Clemastine fumarate powder	255.0USD	g
Clemastine Fumarate 0.67 mg/5ml Syrup 120ml Bottle	22.2USD	bottle
Clemastine Fumarate 2.68 mg tablet	0.9USD	tablet
Clemastine fum 2.68 mg tablet	0.86USD	tablet
Tavist nd 10 mg tablet	0.74USD	tablet
Clemastine fum 1.34 mg tablet	0.58USD	tablet
Tavist-1 1.34 mg tablet	0.5USD	tablet
Clemastine Fumarate 1.34 mg tablet	0.34USD	tablet
Dayhist tablet	0.31USD	tablet
CVS Pharmacy dayhist allergy tablet	0.28USD	tablet
Dayhist-1 1.34 mg tablet	0.25USD	tablet
Tavist max-str sinus caplet	0.17USD	caplet

DrugBank does not sell nor buy drugs. Pricing information is supplied for informational purposes only.

Patents

Not Available

Properties

State

Solid

Experimental Properties

Property	Value	Source
melting point (°C)	178 °C (hydrogen fumarate formulation)	Not Available
water solubility	Soluble (hydrogen fumarate formulation)	Not Available
logP	5.2	Not Available

Predicted Properties

Property	Value	Source
Water Solubility	0.000405 mg/mL	ALOGPS
logP	5.29	ALOGPS
logP	4.92	Chemaxon
logS	-5.9	ALOGPS
pKa (Strongest Basic)	9.55	Chemaxon
Physiological Charge	1	Chemaxon
Hydrogen Acceptor Count	2	Chemaxon
Hydrogen Donor Count	0	Chemaxon
Polar Surface Area	12.47 Å²	Chemaxon
Rotatable Bond Count	6	Chemaxon
Refractivity	101.65 m³·mol^-1	Chemaxon
Polarizability	39.06 Å³	Chemaxon
Number of Rings	3	Chemaxon
Bioavailability	1	Chemaxon
Rule of Five	Yes	Chemaxon
Ghose Filter	Yes	Chemaxon
Veber's Rule	Yes	Chemaxon
MDDR-like Rule	Yes	Chemaxon

Predicted ADMET Features

Property	Value	Probability
Human Intestinal Absorption	+	0.9942
Blood Brain Barrier	+	0.9918
Caco-2 permeable	+	0.6652
P-glycoprotein substrate	Substrate	0.6659
P-glycoprotein inhibitor I	Inhibitor	0.808
P-glycoprotein inhibitor II	Inhibitor	0.8388
Renal organic cation transporter	Inhibitor	0.8471
CYP450 2C9 substrate	Non-substrate	0.819
CYP450 2D6 substrate	Non-substrate	0.9116
CYP450 3A4 substrate	Substrate	0.7176
CYP450 1A2 substrate	Non-inhibitor	0.9045
CYP450 2C9 inhibitor	Non-inhibitor	0.907
CYP450 2D6 inhibitor	Inhibitor	0.8931
CYP450 2C19 inhibitor	Inhibitor	0.8993
CYP450 3A4 inhibitor	Inhibitor	0.7028
CYP450 inhibitory promiscuity	High CYP Inhibitory Promiscuity	0.5
Ames test	Non AMES toxic	0.7454
Carcinogenicity	Non-carcinogens	0.8549
Biodegradation	Not ready biodegradable	0.9972
Rat acute toxicity	2.9450 LD50, mol/kg	Not applicable
hERG inhibition (predictor I)	Strong inhibitor	0.5986
hERG inhibition (predictor II)	Inhibitor	0.8702

ADMET data is predicted using admetSAR, a free tool for evaluating chemical ADMET properties. (23092397)

Spectra

Mass Spec (NIST)

Not Available

Spectra

Spectrum	Spectrum Type	Splash Key
Predicted GC-MS Spectrum - GC-MS	Predicted GC-MS	splash10-0159-9381000000-2be9b3484b69dbb1ec63
Predicted MS/MS Spectrum - 10V, Positive (Annotated)	Predicted LC-MS/MS	splash10-001l-1915000000-e47fd592bf1617d681f6
Predicted MS/MS Spectrum - 10V, Negative (Annotated)	Predicted LC-MS/MS	splash10-0006-3197000000-7c3770d8fb13d8cd5bb3
Predicted MS/MS Spectrum - 20V, Negative (Annotated)	Predicted LC-MS/MS	splash10-0006-7901000000-d5c2eef4c56ee9ad9cf2
Predicted MS/MS Spectrum - 20V, Positive (Annotated)	Predicted LC-MS/MS	splash10-001i-4931000000-00255db249ba328f7dad
Predicted MS/MS Spectrum - 40V, Negative (Annotated)	Predicted LC-MS/MS	splash10-0gc9-3920000000-2f3d62f3e87a8448c45a
Predicted MS/MS Spectrum - 40V, Positive (Annotated)	Predicted LC-MS/MS	splash10-000i-1900000000-f3705f9d64e00d2015a8
Predicted 1H NMR Spectrum	1D NMR	Not Applicable
Predicted 13C NMR Spectrum	1D NMR	Not Applicable

Chromatographic Properties

Collision Cross Sections (CCS)

Adduct	CCS Value (Å²)	Source type	Source
[M-H]-	177.003609	predicted	DarkChem Lite v0.1.0
[M-H]-	177.78992	predicted	DeepCCS 1.0 (2019)
[M+H]+	177.232009	predicted	DarkChem Lite v0.1.0
[M+H]+	180.19118	predicted	DeepCCS 1.0 (2019)
[M+Na]+	177.162709	predicted	DarkChem Lite v0.1.0
[M+Na]+	187.35234	predicted	DeepCCS 1.0 (2019)

Targets

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Details1. Histamine H1 receptor

Kind: Protein
Organism: Humans
Pharmacological action: Yes
Actions: Antagonist

General Function: Histamine receptor activity
Specific Function: In peripheral tissues, the H1 subclass of histamine receptors mediates the contraction of smooth muscles, increase in capillary permeability due to contraction of terminal venules, and catecholamin...
Gene Name: HRH1
Uniprot ID: P35367
Uniprot Name: Histamine H1 receptor
Molecular Weight: 55783.61 Da

References

Chen X, Ji ZL, Chen YZ: TTD: Therapeutic Target Database. Nucleic Acids Res. 2002 Jan 1;30(1):412-5. [Article]
Taniguchi K, Urakami M, Takanaka K: [Effects of antiallergic agents on polymorphonuclear leukocytes. The inhibition of arachidonic acid release and superoxide production]. Nihon Yakurigaku Zasshi. 1987 Aug;90(2):97-103. [Article]
Hallberg T, Dohlsten M, Baldetorp B: Demonstration of histamine receptors on human platelets by flow cytometry. Scand J Haematol. 1984 Feb;32(2):113-8. [Article]
Dorsch W, Hintschich C, Neuhauser J, Weber J: Sequential histamine inhalations cause increased bronchial histamine reactivity in guinea pigs: role of platelets, thromboxanes and prostacyclin. Naunyn Schmiedebergs Arch Pharmacol. 1984 Sep;327(2):148-55. [Article]
Taniguchi K, Masuda Y, Takanaka K: Inhibitory effects of histamine H1 receptor blocking drugs on metabolic activations of neutrophils. J Pharmacobiodyn. 1991 Feb;14(2):87-93. [Article]
Oishi R, Shishido S, Yamori M, Saeki K: Comparison of the effects of eleven histamine H1-receptor antagonists on monoamine turnover in the mouse brain. Naunyn Schmiedebergs Arch Pharmacol. 1994 Feb;349(2):140-4. [Article]
Thomas RH, Browne PD, Kirby JD: The influence of ranitidine, alone and in combination with clemastine, on histamine-mediated cutaneous weal and flare reactions in human skin. Br J Clin Pharmacol. 1985 Oct;20(4):377-82. [Article]
Thomson NC, Kerr JW: Effect of inhaled H1 and H2 receptor antagonist in normal and asthmatic subjects. Thorax. 1980 Jun;35(6):428-34. [Article]
Hayashi H, Okajima M, Yamada K: Atrial T (Ta) loop in dogs with or without atrial injury. Am Heart J. 1976 May;91(5):607-17. [Article]
Schran HF, Petryk L, Chang CT, O'Connor R, Gelbert MB: The pharmacokinetics and bioavailability of clemastine and phenylpropanolamine in single-component and combination formulations. J Clin Pharmacol. 1996 Oct;36(10):911-22. [Article]

Enzymes

Details1. Cytochrome P450 2D6

Kind: Protein
Organism: Humans
Pharmacological action: Unknown
Actions: Inhibitor

General Function: Steroid hydroxylase activity
Specific Function: Responsible for the metabolism of many drugs and environmental chemicals that it oxidizes. It is involved in the metabolism of drugs such as antiarrhythmics, adrenoceptor antagonists, and tricyclic...
Gene Name: CYP2D6
Uniprot ID: P10635
Uniprot Name: Cytochrome P450 2D6
Molecular Weight: 55768.94 Da

References

Flockhart Table of Drug Interactions [Link]

Drug created at June 13, 2005 13:24 / Updated at January 02, 2024 23:44

Clemastine

Identification

Structure for Clemastine (DB00283)

Pharmacology

Interactions

Products

Categories

Chemical Identifiers

References

Clinical Trials

Pharmacoeconomics

Properties

Spectra

Collision Cross Sections (CCS)

Targets

References

Enzymes

References