Mechanism of action
Selective antagonist of peripheral histamine H1receptors, hydroxyzine metabolite. It has antiallergic effect by inhibiting the late phase of the migration of cells involved in the inflammatory response (mainly eosinophils); also reduces the expression of adhesion molecules such as ICAM-1 and VCAM-1, which are markers of allergic inflammation. Suppresses the effect of other mediators and inductors of histamine secretion, such as PAF (platelet-activating factor) and substance P.
Zyrtec suppresses skin reactions in patients with cold urticaria and dermographism. When using the drug in a dose of 5 to 10 mg in patients with mild asthma, the development of bronchospasm caused by a high concentration of histamine, administered as an aerosol, was almost completely blocked.
A six-week study involving 168 patients with allergic rhinitis in combination with mild and moderate bronchial asthma demonstrated the effectiveness of Cetirizine at a dose of 10 mg for rhinitis and showed the safety of cetirizine in patients with allergic rhinitis and mild and moderate bronchial asthma.
The administration of cetirizine in doses exceeding 6 times the daily therapeutic dose (60 mg / day) and placebo as a control for 7 days did not reveal prolongation of the QT interval on the ECG.
The effect of the drug begins 20 minutes after a single dose in a single dose of 10 mg in 50% of patients and after 1 hour in 95% and lasts for 24 hours; not detected tolerance to its antihistamine effect. The skin regains its normal reactivity to histamine 3 days after stopping the drug.
The use of Zyrtek in therapeutic doses of 10 mg / day improved the quality of life of patients with year-round and seasonal allergic rhinitis.
Indications and usage
For adults and children ages 1 and older, treatment of symptoms:
- year-round and seasonal allergic rhinitis and allergic conjunctivitis, such as itching, sneezing, rhinorrhea, tearing, conjunctival hyperemia;
- hay fever (pollinosis);
- urticaria (including chronic idiopathic urticaria) and angioedema.
- Other allergic dermatosis, accompanied by itching and rashes.
Symptoms: drowsiness, restlessness, moderate intensity, itching, rash, urinary retention, fatigue, tremor, tachycardia are possible.None of the described cases of overdose had a fatal or life threatening condition.
Treatment: conduct symptomatic therapy. There is no specific antidote. Hemodialysis is not effective.
Clinically significant interaction of the drug Zyrtec with other drugs is not marked.
Tablets should be stored in a dry place at temperatures below 25 ° C. Solution-drops should be stored at room temperature (15 ° to 25 ° C). The shelf life of the drug is 5 years.
The drug is approved for use as a means of OTC.