Zyrtec

Cetirizine dihydrochloride.

Cetirizine dihydrochloride, 10 mg, film-coated tablet: Each film-coated tablet contains 10 mg of cetirizine dihydrochloride.
Cetirizine dihydrochloride, 1 mg/ml, oral solution: Each 1 ml contains 1 mg of cetirizine dihydrochloride.
Cetirizine dihydrochloride, 10 mg/ml, oral drops, solution: Each 1 ml contains 10 mg of cetirizine dihydrochloride.
Excipients/Inactive Ingredients: Cetirizine dihydrochloride, 10 mg, film-coated tablet: Microcrystalline cellulose, Lactose monohydrate, Colloidal anhydrous silica, Magnesium stearate, Opadry Y-1-7000 which consists of Hydroxypropylmethylcellulose (E464), Titanium dioxide (E171), Macrogol 400.
Cetirizine dihydrochloride, 1 mg/ml, oral solution: Sorbitol solution at 70% (non crystallizing), Glycerol (85%), Propylene glycol, Sodium saccharinate, Methyl parahydroxybenzoate, Propyl parahydroxybenzoate, Banana flavour 54.330/A, Sodium Acetate, Glacial Acetic Acid, Purified water.
Cetirizine dihydrochloride, 10 mg/ml, oral drops, solution: Glycerol (85%), Propylene glycol, Sodium saccharinate, Methyl parahydroxybenzoate, Propyl parahydroxybenzoate, Sodium acetate, Glacial acetic acid, Purified water.

Pharmacotherapeutic group: Antihistamines for systemic use, piperazine derivatives. ATC Code: R06AE07.
Pharmacology: Pharmacodynamics: Mechanism of Action and Pharmacodynamic Effects: Cetirizine, a human metabolite of hydroxyzine, is a potent and selective antagonist of peripheral H₁-receptors. In vitro receptor binding studies have shown no measurable affinity for other than H₁-receptors.
Ex vivo experiments in mice have shown that systemically administered cetirizine does not significantly occupy the cerebral H₁-receptors.
In addition to its anti-H₁ effect, cetirizine was shown to display anti-allergic activities: at a dose of 10 mg once or twice daily, it inhibits the late phase recruitment of inflammatory cells, notably eosinophils, in the skin and conjunctiva of atopic subjects submitted to antigen challenge, and the dose of 30 mg/day inhibits the influx of eosinophils in the bronchoalveolar lavage fluid during a late-phase bronchial constriction induced by allergen inhalation in asthmatic subjects. Moreover, cetirizine inhibits the late-phase inflammatory reaction induced in chronic urticaria patients by intradermal administration of kallikrein. It also down-regulates the expression of adhesion molecules, such as ICAM-1 and VCAM-1, which are markers of allergic inflammation.
Studies in healthy volunteers show that cetirizine, at doses of 5 and 10 mg strongly inhibits the wheal and flare reactions induced by very high concentrations of histamine into the skin, but the correlation with efficacy is not established. The onset of activity after a single 10 mg dose occurs within 20 minutes in 50% of the subjects and within one hour in 95%. This activity persists for at least 24 hours after a single administration.
In a six-week, placebo-controlled study of 186 patients with allergic rhinitis and concomitant mild to moderate asthma, cetirizine 10 mg once daily improved rhinitis symptoms and did not alter pulmonary function. This study supports the safety of administering cetirizine to allergic patients with mild to moderate asthma.
In a placebo-controlled study, cetirizine given at the high daily dose of 60 mg for seven days did not cause statistically significant prolongation of QT interval.
At the recommended dosage, cetirizine has demonstrated that it improves the quality of life of patients with perennial and seasonal allergic rhinitis.
In a 35-day study in children aged 5 to 12, no tolerance to the antihistaminic effect (suppression of wheal and flare) of cetirizine was found. When treatment with cetirizine is stopped after repeated administration, the skin recovers its normal reactivity to histamine within 3 days.
Pharmacokinetics: Absorption: The steady-state peak plasma concentration is approximately 300 ng/ml and is achieved within 1.0 ± 0.5 h.
The distribution of pharmacokinetic parameters such as peak plasma concentration (C_max) and area under the curve (AUC), is unimodal.
The extent of absorption of cetirizine is not reduced with food, although the rate of absorption is decreased. The extent of bioavailability is similar when cetirizine is given as solutions, capsules or tablets.
Distribution: The apparent volume of distribution is 0.50 l/kg. Plasma protein binding of cetirizine is 93 ± 0.3%. Cetirizine does not modify the protein binding of warfarin.
Metabolism and Elimination: Cetirizine does not undergo extensive first pass metabolism. About two-thirds of the dose is excreted unchanged in urine. The terminal half-life is approximately 10 hours and no accumulation is observed for cetirizine following daily doses of 10 mg for 10 days. Cetirizine exhibits linear kinetics over the range 5 to 60 mg.
Special patient populations: Children: The half-life of cetirizine was about 6 hours in children of 6-12 years and 5 hours in children 2-6 years.
Elderly: Following a single 10 mg oral dose, half-life increased by about 50% and clearance decreased by 40% in 16 elderly subjects compared to the younger subjects. The decrease in cetirizine clearance in these elderly volunteers appeared to be related to their decreased renal function.
Renal impairment: The pharmacokinetics of the drug was similar in patients with mild impairment (creatinine clearance higher than 40 ml/min) and healthy volunteers. Patients with moderate renal impairment had a 3-fold increase in half-life and 70% decrease in clearance compared to healthy volunteers.
Patients on haemodialysis (creatinine clearance less than 7 ml/min) given a single oral 10 mg dose of cetirizine had a 3-fold increase in half-life and a 70% decrease in clearance compared to normals. Cetirizine was poorly cleared by haemodialysis. Dosing adjustment is necessary in patients with moderate or severe renal impairment.
Hepatic impairment: Patients with chronic liver diseases (hepatocellular, cholestatic, and biliary cirrhosis) given 10 or 20 mg of cetirizine as a single dose had a 50% increase in half-life along with a 40% decrease in clearance compared to healthy subjects.
Dosing adjustment is only necessary in hepatically impaired patients if concomitant renal impairment is present.
Toxicology: Non-Clinical Information: Non-clinical data reveal no special hazard for humans based on conventional studies of safety pharmacology, repeated dose toxicity, genotoxicity, carcinogenic potential, toxicity to reproduction.

Adults and children of 2 years and above: symptomatic treatment of seasonal allergic rhinitis, perennial allergic rhinitis and urticaria of allergic origin.

The tablets need to be swallowed with a glass of liquid.
The drops have to be diluted in liquid, while the solution can be swallowed as such.
Adults: 10 mg (20 drops or 10 ml oral solution or 1 tablet) once daily.
A 5 mg starting dose (10 drops or 5 ml of oral solution or half of the tablet) may be proposed if this leads to satisfactory control of the symptoms.
Children: Children aged from 2 to 6 years: 2.5 mg (5 drops or 2.5 ml of oral solution bid) twice daily.
Children aged from 6 to 12 years: 5 mg (10 drops or 5 ml of oral solution or half of the tablet) twice daily.
Children over 12 years of age: 10 mg (20 drops or 10 ml of oral solution or 1 tablet) once daily.
Elderly: Data do not suggest that the dose needs to be reduced in elderly subjects provided that the renal function is normal.
Patients with moderate to severe renal impairment: Since cetirizine is mainly excreted via renal route, in cases no alternative treatment can be used, the dosing intervals must be individualised according to renal function.
Refer to the table as follows and adjust the dose as indicated. To use this dosing table, an estimate of the patient's creatinine clearance (CL_cr) in ml/min is needed. The CL_cr (ml/min) may be estimated from serum creatinine (mg/dl) determination using the formula as follows: (see equation and Table 1.)

Click on icon to see table/diagram/image


Click on icon to see table/diagram/image

In paediatric patients suffering from renal impairment, the dose will have to be adjusted on an individual basis taking into account the renal clearance, age and body weight of the patient.
Patients with hepatic impairment: No dose adjustment is needed in patients with solely hepatic impairment.
Patients with hepatic impairment and renal impairment: Dose adjustment is recommended (see Patients with renal impairment as previously mentioned).
Route of Administration: For oral use.

Symptoms and signs: Symptoms observed after an important overdose of cetirizine are mainly associated with CNS effects or with effects that could suggest an anticholinergic effect.
Adverse events reported after an intake of at least 5 times the recommended daily dose are: confusion, diarrhoea, dizziness, fatigue, headache, malaise, mydriasis, pruritus, restlessness, sedation, somnolence, stupor, tachycardia, tremor, and urinary retention.
Treatment: There is no known specific antidote to cetirizine.
Should overdose occur, symptomatic or supportive treatment is recommended.
Cetirizine is not effectively removed by haemodialysis.
Management should be as clinically indicated or as recommended by the national poisons centre, where available.

Cetirizine is contraindicated in: hypersensitivity to any of the constituents of this formulation, to hydroxyzine or to any piperazine derivatives.
Patients with severe renal impairment at less than 10 ml/min creatinine clearance.

Alcohol: At therapeutic doses, no clinically significant interactions have been demonstrated with alcohol (for a blood alcohol level of 0.5 g/L). Nevertheless, precaution is recommended if alcohol is taken concomitantly (see Interactions).
Increased risk of urinary retention: Caution should be taken in patients with predisposition factors of urinary retention (e.g. spinal cord lesion, prostatic hyperplasia) as cetirizine may increase the risk of urinary retention (see Adverse Reactions).
Patients at risk of convulsions: Caution in epileptic patients and patients at risk of convulsions is recommended.
Skin reactions: Pruritus and/or urticaria may occur when cetirizine is stopped, even if those symptoms were not present before treatment initiation (see Adverse Reactions). In some cases, the symptoms may be intense and may require treatment to be restarted. The symptoms should resolve when the treatment is restarted.
Allergy skin tests: Allergy skin tests are inhibited by antihistamines and a wash-out period of 3 days is recommended before performing them.
Food: The extent of absorption of cetirizine is not reduced with food, although the rate of absorption is decreased.
Activities requiring mental alertness: In clinical trials, the occurrence of somnolence has been reported in some patients taking Zyrtec. Due caution should therefore be exercised when driving a car or operating potentially dangerous machinery.
Ability to perform tasks that require judgement, motor or cognitive skills: Objective measurements of driving ability, sleep latency and assembly line performance have not demonstrated any clinically relevant effects at the recommended dose of 10 mg.
However, patients who experience somnolence should refrain from driving, engaging in potentially hazardous activities or operating machinery.
Patients intending to drive, engaging in potentially hazardous activities or operating machinery should not exceed the recommended dose and should take their response to the medicinal product into account.
Use in Children: The use of the film-coated tablet formulation is not recommended in children aged less than 6 years since this formulation does not allow for appropriate dose adaptation. It is recommended to use a paediatric formulation of cetirizine.

Fertility: Limited data is available on human fertility but no safety concern has been identified.
Animal data show no safety concern for human reproduction.
Pregnancy: Caution should be exercised when prescribing to pregnant women. For cetirizine prospectively collected data on pregnancy outcomes do not suggest potential for maternal or foetal/embryonic toxicity above background rates.
Animal studies do not indicate direct or indirect harmful effects with respect to pregnancy, embryonal/fetal development, parturition or postnatal development.
Lactation: Caution should be exercised when prescribing cetirizine to lactating women. Cetirizine is excreted in human milk at concentrations representing 25% to 90% of those measured in plasma, depending on sampling time after administration.

Clinical Trial Data: Clinical studies have shown that cetirizine at the recommended dosage has minor adverse effects on the CNS, including somnolence, fatigue, dizziness and headache. In some cases, paradoxical CNS stimulation has been reported.
Although cetirizine is a selective antagonist of peripheral H₁-receptors and is relatively free of anticholinergic activity, isolated cases of micturition difficulty, eye accommodation disorders and dry mouth have been reported.
Instances of abnormal hepatic function with elevated hepatic enzymes accompanied by elevated bilirubin have been reported. Mostly this resolves upon discontinuation of the treatment with cetirizine.
Double-blind controlled clinical trials comparing cetirizine to placebo or other antihistamines at the recommended dosage (10 mg daily for cetirizine), of which quantified safety data are available, included more than 3200 subjects exposed to cetirizine.
From this pooling, the following adverse events were reported for cetirizine 10 mg in the placebo-controlled trials at rates of 1.0% or greater: (see Table 2.)

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Although statistically more common than under placebo, somnolence was mild to moderate in the majority of cases.
Objective tests as demonstrated by other studies have demonstrated that usual daily activities are unaffected at the recommended daily dose in healthy young volunteers.
Paediatric population: Adverse events at rates of 1% or greater in children aged from 6 months to 12 years, included in placebo-controlled clinical trials are: (see Table 3.)

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Post Marketing Data: Adverse drug reactions (ADRs) are listed as follows by MedDRA system organ class and by frequency.
Frequencies are defined as: 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).
Blood and lymphatic disorders: Very rare: thrombocytopenia.
Immune system disorders: Rare: hypersensitivity. Very rare: anaphylactic shock.
Metabolism and nutrition disorders: Not known: increased appetite.
Psychiatric disorders: Uncommon: agitation. Rare: aggression, confusion, depression, hallucination, insomnia. Very rare: tics. Not known: suicidal ideation, nightmare.
Nervous system disorders: Uncommon: paraesthesia. Rare: convulsions. Very rare: dysgeusia, dyskinesia, dystonia, syncope, tremor. Not known: amnesia, memory impairment.
Eye disorders: Very rare: accommodation disorder, blurred vision, oculogyration.
Ear and labyrinth disorders: Not known: vertigo.
Cardiac disorders: Rare: tachycardia.
Gastrointestinal disorders: Uncommon: diarrhoea.
Hepatobiliary disorders: Rare: hepatic function abnormal (transaminases increased, blood bilirubin increased, blood alkaline phosphatase increased, gamma-glutamyl transferase increased). Not known: hepatitis.
Skin and subcutaneous tissue disorders: Uncommon: pruritus, rash. Rare: urticaria. Very rare: angioedema, fixed drug eruption. Not known: acute generalized exanthematous pustulosis (AGEP).
Musculoskeletal and connective tissue disorders: Not known: arthralgia.
Renal and urinary disorders: Very rare: dysuria, enuresis. Not known: urinary retention (see Precautions).
General disorders and administration site conditions: Uncommon: asthenia, malaise. Rare: oedema.
Investigations: Rare: weight increased.
Skin reactions occurring after discontinuation of cetirizine: After discontinuation of cetirizine, pruritus (intense itching) and/or urticaria have been reported (see Precautions).

Due to the pharmacokinetic, pharmacodynamic and tolerance profile of cetirizine, no interactions are expected with this antihistamine. Neither pharmacodynamic nor significant pharmacokinetic interaction was reported in drug-drug interactions studies performed, notably with pseudoephedrine or theophylline (400 mg/day).
Alcohol and other CNS depressants: In sensitive patients, the concurrent use of alcohol or other CNS depressants may cause additional reductions in alertness and impairment of performance, although cetirizine does not potentiate the effect of alcohol (0.5 g/L blood levels) (see Precautions).

Incompatibilities: There are no relevant data available.
Use and Handling: There are no special requirements for use or handling of this product.

Do not store above 30°C. Keep tablets in a dry place.

Antihistamines & Antiallergics

R06AE07 - cetirizine ; Belongs to the class of piperazine derivatives used as systemic antihistamines.

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