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Ketotifen: Wikis


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Systematic (IUPAC) name
4-(1-methylpiperidin-4-ylidene)-4,9-dihydro-10 H-benzo[4,5]cyclohepta[1,2-b]thiophen-10-one
CAS number 34580-14-8
ATC code R06AX17 S01GX08
PubChem 3827
DrugBank APRD01061
Chemical data
Formula C 19H19NOS 
Mol. mass 309.426 g/mol
Pharmacokinetic data
Bioavailability 60%
Protein binding 75%
Metabolism Hepatic
Half life 12 Hours
Excretion  ?
Therapeutic considerations
Pregnancy cat.  ?
Legal status  ? (US) Oral - Prescription, Eye Drops - OTC
Routes Oral, Eye Drops
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Ketotifen fumarate (ophthalmic solutions marketed under the brand name Zaditor (Novartis), Alaway (Bausch and Lomb)), Zyrtec Itchy-Eye Drops, and Claritin Eye, is a second-generation H1-antihistamine/mast cell stabilizer available in two forms. In its ophthalmic form, it is used to treat allergic conjunctivitis, or the itchy red eyes caused by allergies. In its oral form, it is used to prevent asthma attacks. Side effects include drowsiness, weight gain, dry mouth, irritability, and increased nosebleeds.


General information

Ketotifen relieves and prevents eye itchiness and/or irritation associated with most seasonal allergies. It starts working within minutes after administering the drops. The drug has not been studied in children under 3. The mean elimination half life is 12 hours.[1]

Besides its anti-histaminic activity, it is also a functional leukotriene antagonist and a phosphodiesterase inhibitor.

Off-Label Use

Ketotifen is used to up-regulate Beta-2 adrenergic receptors down-regulated by Beta-2 adrenergic agonists. It upregulates adrenergic receptors thanks to its phosphodiesterase inhibition, since a phosphodiesterase enzyme is involved in their feedback/omeostatic pathway.


  1. ^ Grahnén A; Lönnebo A, Beck O, Eckernäs SA, Dahlström B, Lindström B (May 1992). "Pharmacokinetics of ketotifen after oral administration to healthy male subjects". Biopharm Drug Dispos 13 (4): 255–62. doi:10.1002/bdd.2510130404. PMID 1600111.  

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