Ketoifin

[MaNiCC]

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.

4-(1-methylpiperidin-4-ylidene)-4,9-dihydro-10H-benzo[4,5]cyclohepta[1,2-b]thiophen-10-one
Identifiers
CAS number 34580-14-8
ATC code R06AX17 S01GX08
PubChem CID 3827
DrugBank APRD01061

Chemical data
Formula C19H19NOS
Mol. mass 309.426 g/mol

Pharmacokinetic data
Bioavailability 60%
Protein binding 75%
Metabolism Hepatic
Half-life 12 Hours

Therapeutic considerations
Pregnancy cat. C(US)
Legal status OTC (US) Oral – Prescription, Eye Drops – OTC
Routes Oral, Eye Drops
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 three. The mean elimination half life is 12 hours. 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 due to its phosphodiesterase inhibition, since a phosphodiesterase enzyme is involved in their feedback/homeostatic pathway.