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INTERACTIONS
Zaditen may potentiate the effects of CNS
depressants antihistamines and alcohol.
PREGNANCY AND LACTATION
Pregnancy
Although ketotifen was without effect on
pregnancy and on pen-and post-natal
development at dose levels which were
tolerated by the mother animals. its safety in
human pregnancy has nut been established. Zaditen should therefore be given to pregnant
women only in compelling circumstances.
Lactation
Ketotifen is excreted in rat milk. It is assumed
that this drug is also excreted in human breast
milk, and therefore mothers receiving Zaditen
should not breast-feed.
EFFECTS ON ABILITY TO DRIVE AND USE
MACHINES
During the first few days of treatment with Zaditen the patient's reactions may be impaired
and he/she should therefore exercise care when
driving a vehicle or operating machinery.
UNDESIRABLE EFFECTS
Adverse reactions (Table 1 ) are ranked under
heading of frequency, the most frequent first,
using the following convention: 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), including
isolated reports. Within each frequency
grouping, adverse reactions are ranked in order
of decreasing seriousness
Table 1
| Infections and infestations |
|
|
| Uncommon : |
|
Cystitis |
| Immune system disorders |
|
|
| Very rare : |
|
Erythema multiform, Stevens-Johnson syndrome, severe skin
reaction |
| Metabolism and nutrition disorders |
|
|
| Rare : |
|
Weight increased |
| Psychiatric disorders |
|
|
| Common : |
|
Excitation, irritability, insomnia, nervousness |
| Nervous system disorders |
|
|
| Uncommon : |
|
Dizziness |
| Rare : |
|
Sedation |
| Gastrointestinal disorders |
|
|
| Uncommon : |
|
Dry mouth |
| Hepatobiliary disorders |
|
|
| Very rare : |
|
Hepatitis, increase in liver enzymes |
Sedation, dry mouth and dizziness may occur at
the beginning of treatment, but usually disappear
spontaneously with continued medication.
Symptoms of CNS stimulation, such as
excitation, irritability, insomnia, and nervousness,
have been observed particularly in children.
OVERDOSE
The main symptoms of acute overdose include :
drowsiness to severe sedation; confusion and
disorientation. tachycardia and hypotension;
especially in children, hyperexcitability or
convulsions; reversible coma.
Treatment should be symptomatic. If the drug
has been taken very recently, emptying of the
stomach may be considered. Administration of
activated charcoal may be beneficial. It
necessary, symptomatic treatment and
monitoring of the cardiovascular system are
recommended; it excitation or convulsions are
present, short-acting barbiturates or
benzodiazepines may be given.
PHARMACODYNAMICS
Ketotifen is a non-bronchodilator anti-asthmatic
drug which inhibits the effects of certain
endogenous substances known to be
inflammatory mediators, and thereby exerts antiallergic activity.
Laboratory experiments have revealed a number of properties of ketotifen,
which may contribute to its anti-asthmatic activity:
• Inhibition of the release of
allergic mediators such as histamine and leukotrienes
• Suppression of the priming of
eosinophils by human recombinant cytokines and thereby suppression of the
influx of eosinophils into inflammatory loci
• Inhibition of the development
of airway hyper-reactivity associated with activation of platelets by PAF
(platelet-activating factor) or caused by neural activation following the
use of sympathomimetic drugs or the exposure to allergen
Ketotifen is a potent antiallergic substance possessing non-competitive
histamine (H1) blocking properties. Therefore, it can also be
used in place of classical histamine (H1) receptor antagonists.
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