Zyrtec, drops 10 mg/ml 20 ml

Zyrtec is an antihistamine, anti-allergic.

Pharmacodynamics

Cetirizine – the active substance of the drug Zyrtec® – 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 actions. Cetirizine affects the early histamine-dependent stage of allergic reactions, limits the release of inflammatory mediators at the later stage of the allergic reaction, and also reduces migration of eosinophils, neutrophils and basophils and stabilizes mast cell membranes. It 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 (in cold urticaria). Reduces histamine-induced bronchoconstriction in mild bronchial asthma.

Cetirizine has no anticholinergic and antiserotonin effects. In therapeutic doses the drug practically does not cause a sedative effect. After a single dose of 10 mg of cetirizine it causes the action in 20 minutes (in 50% of patients), in 60 minutes (in 95% of patients) and lasts more than 24 hours. During a course of treatment, tolerance to the antihistamine effect of cetirizine does not develop. After discontinuation of therapy the effect lasts up to 3 days.

Pharmacokinetics

The pharmacokinetic parameters of cetirizine change linearly.

Intake. 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 speed decreases. In adults after a single use of the drug in a therapeutic dose Cmax in plasma is 300 ng/ml and is reached in (1±0.5) hours.

Distribution. Cetirizine is (93±0.3)% bound to plasma proteins. Vd is 0.5 l/kg. No cetirizine cumulation is observed when taking the drug in a dose of 10 mg for 10 days.

Metabolism. In small amounts, it is metabolized in the body by O-dealkylation (unlike other H1-histamine receptor antagonists, which are metabolized in the liver via the cytochrome system) to form a pharmacologically inactive metabolite.

Elimination. In adults, T1/2 is approximately 10 h; in children from 6 to 12 years, 6 h; from 2 to 6 years, 5 h; from 6 months to 2 years, 3.1 h. About 2/3 of the taken dose of the drug is excreted unchanged by the kidneys.

In elderly patients and patients with chronic liver disease in single use of the preparation in dose of 10 mg T1/2 is increased approximately by 50%, and systemic clearance is decreased by 40%.

In patients with mild renal impairment (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 Cl1/2 is increased by a factor of 3 and total clearance is decreased by 70% relative to these parameters in patients with normal renal function, which requires appropriate changes in dosing regimen.

Cetirizine is almost not eliminated from the body by hemodialysis.

Indications

Cetirizine Dihydrochloride Oral Drops 10 mg/mL is indicated in adults and children 6 months and older for relief:

– nasal and ocular symptoms of year-round (persistent) and seasonal (intermittent) allergic rhinitis and allergic conjunctivitis: itching sneezing nasal congestion rhinorrhea lacrimation conjunctival hyperemia;

– symptoms of chronic idiopathic urticaria.

The use in children from 6 to 12 months is possible only with the prescription of a physician and under strict medical supervision.

Active ingredient

Composition

The active ingredient:

cetirizine hydrochloride 10 mg;

Excipients:

Glycerol – 250 mg;

Propylene glycol – 350 mg;

sodium saccharinate – 10 mg;

Methylparabenzene – 1.35 mg;

propylparabenzene – 0.15 mg;

sodium acetate – 10 mg;

glacial acetic acid – 0.53 mg;

purified water – up to 1 ml

How to take, the dosage

Ingestion.

Children over 6 years of age and adults: the initial dose is 5 mg (1/2 tablet or 10 drops) once a day, if necessary, can be increased to 10 mg (1 tablet or 20 drops) once a day. Sometimes an initial dose of 5 mg (1/2 tablet or 10 drops) may be sufficient to achieve the therapeutic effect. The daily dose is 10 mg (1 tablet or 20 drops).

Children 6 to 12 months: 2.5 mg (5 drops) once a day.

Children 1 to 2 years: 2.5 mg (5 drops) up to 2 times a day.

Children 2 to 6 years: 2.5 mg (5 drops) 2 times a day or 5 mg (10 drops) once a day.

In patients with renal insufficiency the dose is decreased depending on creatinine clearance: in creatinine Cl 30-49 ml/min – 5 mg once a day, in 10-29 ml/min – 5 mg every other day.

Interaction

In the study of drug interactions of cetirizine with pseudoephedrine, cimetidine, ketoconazole, erythromycin, azithromycin, diazepam, glipizide and antipyrine no clinically significant adverse interactions were found.

Concomitant use with theophylline (400 mg/day) decreases total clearance of cetirizine by 16% (the kinetics of theophylline is not changed).

Concomitant use with ritonavir increased AUC of cetirizine by 40%, while that of ritonavir changed slightly (-11%).

When used concomitantly with macrolides (azithromycin, erythromycin) and ketoconazole there were no changes in the AUC.

When using the drug in therapeutic doses no data on interaction with alcohol (at blood alcohol concentration of 0.5 g/l) were obtained. Nevertheless, it is necessary to refrain from drinking alcohol during the therapy with the drug in order to avoid CNS depression.

A 3-day “washout” period is recommended before allergy testing due to the fact that H1-histamine receptor blockers inhibit cutaneous allergic reactions.

Special Instructions

In patients with spinal cord injury, prostatic hyperplasia, and in the presence of other predisposing factors to urinary retention, caution is required because cetirizine may increase the risk of urinary retention.

It is recommended to refrain from drinking alcohol (see “Interactions”).

Impact on the ability to drive vehicles and operate machinery. No undesirable effects have been reliably detected in objective assessment of the ability to drive vehicles and operate mechanisms when using the drug in the recommended dose. Nevertheless, during the use of the drug it is reasonable to refrain from potentially dangerous activities requiring high concentration and quick psychomotor reactions.

In view of potential CNS depressant effect it is necessary to be careful when prescribing Zirtek® in children under 1 year old in case of the following risk factors of sudden infant death syndrome, such as (but not limited to this list):

Contraindications

– Hypersensitivity to cetirizine hydroxyzine or any piperazine derivatives or other components of the drug;

– terminal renal failure (creatinine clearance < 10 ml/min);

– children under 6 months of age (due to the limited data concerning efficiency and safety of using the drug Zirtek®;

Side effects

Immune system: rare – hypersensitivity reactions; very rare – anaphylactic shock.

Nervous system disorders: often – headache, increased fatigue, dizziness, somnolence; infrequent – paresthesias; rare – seizures; very rare – perversion of taste, dyskinesia, dystonia, syncope, tremor, tics; frequency unknown – memory disorders, including amnesia.

Psychiatric disorders: infrequent – agitation; rare – aggression, confusion, depression, hallucinations, sleep disorders; frequency unknown – suicidal ideation.

An organ of vision: very rare – accommodation disorder, blurred vision, nystagmus.

Hearing organ: frequency is unknown – vertigo.

The digestive system: often – dry mouth, nausea; infrequently – diarrhea, abdominal pain.

System disorders: rarely – tachycardia.

Respiratory system: often – rhinitis, pharyngitis.

Metabolism: rarely – weight gain.

The urinary system: very rare – dysuria, enuresis; frequency unknown – urinary retention.

Laboratory measures: rare – changes of liver function tests (increased liver transaminases activity, alkaline phosphatase, GGT and bilirubin concentration); very rare – thrombocytopenia.

Skin: infrequent – rash, itching, rarely – urticaria, very rare – angioedema, erythema persistent.

General disorders: infrequent – asthenia, malaise; rarely – peripheral edema; frequency unknown – increased appetite.

Overdose

Symptoms (when taken once in a dose of 50 mg): confusion, diarrhea, dizziness, fatigue, headache, malaise, mydriasis, itching, weakness, restlessness, sedation, drowsiness, stupor, tachycardia, tremor, urinary retention.

Treatment: immediately after taking the drug – gastric lavage or induction of vomiting. Administration of activated charcoal, symptomatic and supportive therapy is recommended. There is no specific antidote. Hemodialysis is ineffective.

Pregnancy use

Pregnancy

An analysis of prospective data from more than 700 cases of pregnancy outcomes showed no cases of fetal and neonatal toxicity malformations with a clear causal relationship.

The experimental studies on animals did not reveal any direct or indirect adverse effects of cetirizine on the developing fetus (including in the postnatal period) during pregnancy and postnatal development.

There have been no adequate and strictly controlled clinical studies on the safety of the drug during pregnancy; therefore, Zyrtec® should not be used during pregnancy.

Breastfeeding

Cetirizine is excreted with breast milk at concentrations of 25% to 90% of the drug concentration in blood plasma, depending on the time after administration. During breastfeeding, use after consultation with a physician if the estimated benefit to the mother exceeds the potential risk to the baby.

Fertility

The available data on the effects on human fertility are limited but no negative effects on fertility have been identified.

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