Symptoms (when taking the drug in a dose of more than 5 tablets): signs of intoxication in the form of drowsiness, in children — anxiety, increased irritability, there may be signs of anticholinergic action in the form of urinary retention, dry mouth, constipation.
Treatment: you should stop taking the drug, clear your stomach, take activated charcoal, and immediately consult a doctor.
When studying the drug interaction of cetirizine with pseudoephedrine, cimetidine, ketoconazole, erythromycin, azithromycin, diazepam, glipizide and antipyrine, clinically significant adverse interactions were not detected.
When used concomitantly with theophylline (400 mg / day), the total clearance of cetirizine decreases by 16% (the kinetics of theophylline does not change).
When used concomitantly with ritonavir, the AUC of cetirizine increased by 40%, while the same indicator of ritonavir slightly changed (-11%).
Concomitant use with macrolides (azithromycin, erythromycin) and ketoconazole showed no ECG changes.
When using the drug in therapeutic doses, no data were obtained on the interaction with alcohol (at a blood alcohol concentration of 0.5 g/l). However, you should refrain from drinking alcohol during therapy with the drug in order to avoid depression of the central nervous system.
Before the appointment of allergological tests, a three-day "washing" period is recommended due to the fact that H1- histamine receptor blockers inhibit the development of skin allergic reactions.
No drug interactions of cetirizine with other drugs were observed.
Based on the results of the conducted studies of drug interaction of cetirizine, in particular, studies of interaction with pseudoephedrine or theophylline at a dose of 400 mg/day, no clinically significant interactions were established.
Concomitant use of cetirizine with alcohol and other drugs that depress the central nervous system may contribute to a further decrease in concentration and reaction speed, although cetirizine does not enhance the effect of alcohol (at its concentration in the blood of 0.5 g/l).
It is not recommended to combine the drug with other drugs Since without consulting a doctor. When taken simultaneously with bronchodilators containing theophylline as the active substance, an increase in the frequency of side effects of the drug Zincet. Data on the interaction of cetirizine with alcohol have not yet been obtained. Despite this, the consumption of alcoholic beverages in the treatment of drug Since is not recommended.
It is not recommended to combine Alerest with other drugs without consulting a doctor. When taken simultaneously with bronchodilators containing theophylline as the active substance, an increase in the frequency of side effects of the drug Alerest. Data on the interaction of cetirizine with alcohol have not yet been obtained. Despite this, the use of alcoholic beverages in the treatment of Alerest is not recommended.
Usually the drug is well tolerated. In some cases, there may be headache, drowsiness, dizziness, agitation, dry mouth, gastrointestinal disorders: dyspepsia, abdominal pain, flatulence. As an exception, there may be signs of hypersensitivity to the drug (urticaria, edema, shortness of breath). In this case, treatment with the drug should be stopped immediately and urgently consult a doctor. It is necessary to inform the doctor about all side (unusual) effects.
Cetirizine-the active substance of the drug Alerest® — it is a metabolite of hydroxyzine, belongs to the group of competitive histamine antagonists and blocks H1- histamine receptors.
Cetirizine prevents the development and facilitates the course of allergic reactions, has antipruritic and antiexudative effects. Cetirizine affects the early histamine-dependent stage of allergic reactions, restricts the release of inflammatory mediators at the late stage of an allergic reaction, and also reduces the migration of eosinophils, neutrophils and basophils, and stabilizes the membranes of mast cells. Reduces capillary permeability, prevents the development of tissue edema, relieves smooth muscle spasm. Eliminates the skin reaction to the introduction of histamine, specific allergens, as well as cooling (with cold urticaria). Reduces histamine-induced bronchoconstriction in mild bronchial asthma
Cetirizine does not have anticholinergic and antiserotonin effects. In therapeutic doses, the drug practically does not cause a sedative effect. After taking cetirizine in a single dose of 10 mg, its effect develops after 20 minutes (in 50% of patients), after 60 minutes (in 95% of patients) and lasts for more than 24 hours.Against the background of course treatment, tolerance to the antihistamine action of cetirizine does not develop. After discontinuation of therapy, the effect persists for up to 3 days.
Cetirizine is a metabolite of hydroxyzine, belongs to the group of competitive histamine antagonists and blocks H1- histamine receptors.
In addition to the antihistamine effect, cetirizine prevents the development and facilitates the course of allergic reactions: at a dose of 10 mg 1 or 2 times a day, it inhibits the late phase of eosinophil aggregation in the skin and conjunctiva of patients exposed to atopy.
Clinical efficacy and safety. Studies in healthy volunteers have shown that cetirizine at doses of 5 or 10 mg significantly inhibits the reaction in the form of rash and redness to the introduction of histamine into the skin in high concentrations, but a correlation with the effectiveness has not been established. In a 6-week placebo-controlled study involving 186 patients with allergic rhinitis and concomitant bronchial asthma of mild and moderate severity, it was shown that taking cetirizine at a dose of 10 mg once a day reduces the symptoms of rhinitis and does not affect lung function.
The results of this study confirm the safety of cetirizine in patients suffering from allergies and mild to moderate bronchial asthma.
In a placebo-controlled study, it was shown that taking cetirizine at a dose of 60 mg / day for 7 days did not cause a clinically significant prolongation of the QT interval. Taking cetirizine at the recommended dose showed an improvement in the quality of life of patients with year-round and seasonal allergic rhinitis.
Children. In a 35-day study involving patients aged 5-12 years, there were no signs of immunity to the antihistamine effect of cetirizine. The normal reaction of the skin to histamine was restored within 3 days after discontinuation of the drug with its repeated use.
In a 7-day placebo-controlled trial of cetirizine in the dosage form syrup with 42 patients aged 6 to 11 months, the safety of the drug was demonstrated.
Cetirizine was administered at a dose of 0.25 mg / kg 2 times a day, which approximately corresponded to 4.5 mg per day (the dose range was from 3.4 to 6.2 mg per day).
Use in children from 6 to 12 months is possible only on the prescription of a doctor and under strict medical supervision.
The pharmacokinetic parameters of cetirizine vary linearly.
Suction. After oral administration, the drug is quickly and completely absorbed from the gastrointestinal tract. Food intake does not affect the completeness of absorption, although its rate decreases. In adults after a single dose of the drug at a therapeutic dose of Cmax in the blood plasma is 300 ng / ml and is reached after (1±0.5) hours.
Distribution. Cetirizine binds to plasma proteins by (93±0.3)%. Vd it is 0.5 l/kg. When taking the drug at a dose of 10 mg for 10 days, cetirizine accumulation is not observed.
Metabolism. In small amounts, it is metabolized in the body by O-dealkylation (unlike other H antagonists1- histamine receptors, which are metabolized in the liver by the cytochrome system) to form a pharmacologically inactive metabolite.
Output. In adults, T1/2 it is approximately 10 hours, in children from 6 to 12 years — 6 hours, from 2 to 6 years-5 hours, from 6 months to 2 years-3.1 hours. Approximately 2/3 of the dose of the drug is excreted by the kidneys in unchanged form.
In elderly patients and patients with chronic liver diseases with a single dose of the drug at a dose of 10 mg T1/2 increases by about 50%, and system clearance decreases by 40%.
In patients with mild renal insufficiency (creatinine Cl >40 ml/min), the pharmacokinetic parameters are similar to those in patients with normal renal function.
In patients with moderate renal insufficiency and in patients on hemodialysis (creatinine Cl <7 ml / min), when taking the drug orally at a dose of 10 mg T1/2 it is prolonged by 3 times, and the total clearance is reduced by 70% relative to these indicators in patients with normal renal function, which requires a corresponding change in the dosage regimen.
Cetirizine is practically not removed from the body during hemodialysis.
The pharmacokinetic parameters of cetirizine when used in doses from 5 to 60 mg vary linearly.
Suction. Cmax in the blood plasma, it is reached after (1±0.5) h and is 300 ng / ml.
Various pharmacokinetic parameters, such as Cmax in blood plasma and AUC, have a homogeneous character.
Food intake does not affect the full absorption of cetirizine, although its rate decreases. The bioavailability of various dosage forms of cetirizine (solution, capsules, tablets) is comparable.
Distribution. Cetirizine binds to plasma proteins by (93±0.3)%.
Vd it is 0.5 l/kg. Cetirizine does not affect the binding of warfarin to proteins.
Metabolism. Cetirizine does not undergo extensive primary metabolism.
Output. T1/2 it is approximately 10 hours.
When taking the drug at a daily dose of 10 mg for 10 days, cetirizine accumulation was not observed.
Approximately 2/3 of the taken dose of the drug is excreted in the urine in an unchanged form.
Elderly patients. In 16 elderly patients with a single dose of the drug at a dose of 10 mg T1/2 It was 50% higher and clearance was 40% lower compared to non-elderly patients. The decrease in cetirizine clearance in elderly patients is probably associated with a decrease in renal function in this category of patients.
Kidney failure. In patients with mild renal insufficiency (creatinine Cl >40 ml/min), the pharmacokinetic parameters are similar to those in healthy volunteers with normal renal function.
In patients with moderate renal insufficiency and in patients on hemodialysis (creatinine Cl <7 ml / min), when taking the drug orally at a dose of 10 mg T1/2 it is extended by 3 times, and the total clearance is reduced by 70% relative to healthy volunteers with normal kidney function.
For patients with moderate or severe renal insufficiency, a corresponding change in the dosage regimen is required (see "Method of administration and doses").
Cetirizine is poorly removed from the body during hemodialysis.
Liver failure. In patients with chronic liver diseases (hepatocellular, cholestatic and biliary cirrhosis) with a single dose of the drug at a dose of 10 or 20 mg T1/2 increases by about 50%, and clearance decreases by 40% compared to healthy subjects. Dose adjustment is only necessary in the case of a patient with hepatic insufficiency there is also a concomitant renal failure.
Children. T1/2 in children from 6 to 12 years is 6 hours, from 2 to 6 years-5 hours, from 6 months to 2 years-reduced to 3.1 hours.
