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Ketotifen

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Ketotifen
Clinical data
Routes of
administration
Oral, Eye Drops
ATC code
Legal status
Legal status
  • US: ℞-only
  • Oral - Prescription, Eye Drops - OTC
Pharmacokinetic data
Bioavailability60%
Protein binding75%
MetabolismHepatic
Elimination half-life12 Hours
Identifiers
  • 4-(1-methylpiperidin-4-ylidene)-4,9-dihydro-10H-benzo[4,5]cyclohepta[1,2-b]thiophen-10-one
CAS Number
PubChem CID
DrugBank
CompTox Dashboard (EPA)
ECHA InfoCard100.047.348 Edit this at Wikidata
Chemical and physical data
FormulaC19H19NOS
Molar mass309.426 g/mol g·mol−1
  (verify)

Ketotifen fumarate 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.

The drug is marketed as ophthalmic solutions under the brand names Zaditor (Novartis), Alaway (Bausch and Lomb)), Zyrtec Itchy-Eye Drops, and Claritin Eye.

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.

References

  1. ^ Grahnén A (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. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |month= ignored (help)