Chemical formula: C₁₉H₁₉NOS Molecular mass: 309.425 g/mol PubChem compound: 3827
Ketotifen interacts in the following cases:
The use of oral dosage forms of ketotifen may potentiate the effect of CNS depressants, antihistamines and alcohol. Although this has not been observed with ketotifen eye drops, the possibility of such effects cannot be excluded.
Thrombocytopenia may occur in patients taking ketotifen at the same time as oral antidiabetic drugs (biguanides). The simultaneous administration of these drugs should therefore be avoided.
Convulsions have been reported very rarely during ketotifen therapy. As ketotifen may lower the seizure threshold it should be used with caution in patients with a history of epilepsy.
There are no or limited amount of data from the use of ketotifen in pregnant women. Animal studies do not indicate direct or indirect harmful effects with respect to reproductive toxicity. Ketotifen should not be used during pregnancy unless the clinical condition of the woman requires treatment with ketotifen.
There are no adequate data from the use of ketotifen eye drops in pregnant women. Animal studies using maternally toxic oral doses showed increased pre-and postnatal mortality, but no teratogenicity. Systemic levels after ocular administration are much lower than after oral use. Caution should be exercised when prescribing to pregnant women.
Available data in rats have shown excretion of ketotifen in milk, while there is no human data available. It is assumed that this drug is also excreted in human breast milk, and therefore mothers receiving ketotifen should not breast-feed.
Although animal data following oral administration show excretion into breast milk, topical administration to human is unlikely to produce detectable quantities in breast milk. Ketotifen eye drops can be used during lactation.
There is no data to support any special recommendations in women of child-bearing potential.
Treatment of male rats with a toxic oral dose of ketotifen (50 mg/kg/day) for 10 weeks prior to mating resulted in decreased fertility, but was not impaired at doses relevant for human use. The fertility of female rats as well as prenatal development, pregnancy and weaning of the offspring were not adversely affected by ketotifen treatment at oral dose levels of up to 50 mg/kg per day. There is no data available on the effect of ketotifen SRO on fertility in humans.
There are no data available on the effect of ketotifen fumarate on fertility in humans.
During the first days of treatment with ketotifen reactions may be impaired. Patients should be warned not to take charge of vehicles or machinery until the effect of ketotifen treatment on the individual is known. Patients should be advised to avoid alcoholic drinks.
Any patient who experiences blurred vision or somnolence should not drive or operate machines.
Adverse drug reactions from clinical trials, spontaneous reports and literature cases are listed by MedDRA system organ class. Adverse drug reactions are ranked under heading of Preferred Term (PT) frequency, the most frequent first. Since reactions from spontaneous reports and literature cases are reported voluntarily from a population of uncertain size, it is not possible to reliably estimate their frequency which is therefore categorized as not known. The following convention is used: very common (≥1/10); common (≥1/100, <1/10); uncommon (≥1/1,000, <1/100); rare (≥1/10,000, <1/1,000) very rare (<1/10,000), not known (cannot be estimated from the available data), including isolated reports. Within each frequency grouping, adverse reactions are ranked in order of decreasing seriousness.
Uncommon: Cystitis
Very rare: Erythema multiforme, Stevens-Johnson syndrome, Severe cutaneous adverse reaction
Rare: Weight increased
Common: Agitation, irritability, insomnia, nervousness
Uncommon: Dizziness*
Rare: Sedation*
Not known: Convulsions, somnolence, headache
Uncommon: Dry mouth*
Not known: Vomiting, nausea, diarrhea
Very rare: Hepatitis, hepatic enzymes increased
Not known: Rash, urticaria
* Somnolence and sedation, dry mouth and dizziness may occur at the beginning of treatment, but usually disappear spontaneously with continued medication. There have been reports of nausea, vomiting, headache, convulsion, urticaria and rash.
** Symptoms of CNS stimulation, such as agitation, irritability, insomnia and nervousness have been observed particularly in children.
Adverse reactions are ranked under heading of frequency, using the following convention: Very common (≥1/10); common (≥1/100 to <1/10); uncommon (≥1/1,000 to <1/100); rare (≥1/10,000 to <1/1,000); very rare (<1/10,000), not known (cannot be estimated from the available data).
Uncommon: Hypersensitivity
Uncommon: Headache
Common: Eye irritation, eye pain, punctate keratitis, punctate corneal epithelial erosion.
Uncommon: Vision blurred (during instillation), dry eye, eyelid disorder, conjunctivitis, photophobia, conjunctival haemorrhage.
Uncommon: Dry mouth
Uncommon: Rash, eczema, urticarial
Uncommon: Somnolence
Adverse drug reactions from post-marketing experience (Frequency not known): The following post marketing events have also been observed: hypersensitivity reactions including local allergic reaction (mostly contact dermatitis, eye swelling, eyelid pruritis and oedema), systemic allergic reactions including facial swelling/oedema (in some cases associated with contact dermatitis) and exacerbation of pre-existing allergic conditions such as asthma and eczema.
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