3          PHARMACUTICAL FORM

Clear solution

4.1        Therapeutic Indications

In adults and children 2 years of age and above

4.2        Posology and Method of Administration

            Adults and Children over 12 years: 10mg (10ml oral suspension 2 full spoons) once a day.

Children between 6 and 12 years: 5 mg (5 ml a full spoonful) twice a day.

Children between 2 and 6 years for seasonal rhinitis (hayfever):  (2.5 ml oral solution twice daily) a half spoonful twice a day.

At present there are insufficient clinical data to recommend use of cetirizine in children under 2 years of age. 

Patients with moderate to severe renal impairment

The dosing intervals must be individualized according to renal function. Refer to the following table and adjust the dose as indicated. To use this dosing table, an estimate of the patient’s creatinine clearance (CLcr) in ml/min is needed. The CLcr (ml/min) may be estimated from serum creatinine (mg/dl) determination using the following formula:

Dosing adjustments for adult patients with impaired renal function

In paediatric patients who suffer from renal impairment, the dose will have to be adjusted on an individual basis taking into account the renal clearance of the patient and his body weight.

Patients with hepatic impairment

No dose adjustment is required in patients with solely hepatic impairment.

Patients with hepatic impairment and renal impairment

Adjustment of the dose is recommended (see Patients with renal impairment above).

Cetirizine dihydrochloride is contraindicated in patients with severe renal impairment. In patients with moderate renal impairment the dose should be adjusted to 5 mg (1/2 tablet per day). Caution should be exercised in patients with mild to moderate renal impairment or impaired liver function (see section 4.4 Special warnings and precautions for use).

Elderly subjects

Data do not suggest that the dose needs to be reduced in elderly subjects provided that the renal function is normal.

4.3        Contra-indications

-           History of hypersensitivity to any of the constituents of the formulation, to hydroxyzine or to any piperazine derivatives.

-           Patients with severe renal impairment at less than 10 ml/min creatinine clearance

-           Patients with rare hereditary problems of fructose intolerance should not take cetirizine 1 mg/ml oral solution.

4.4        Special Warnings and Special Precautions for Use

At therapeutic doses, no clinically significant interactions have been demonstrated with alcohol (blood alcohol level of 0.5 g/L). Although precaution is recommended if taken concomitantly with alcohol.

Caution in epileptic patients and patients’ at risk of convulsions is recommended.

The use of the product is not recommended in children aged less than 2 years (see section 4.2)..

Methyl parahydroxybenzoate and propyl parahydroxybenzoate included in the 10 mg/ml oral drops and in the 1 mg/ml oral solution may cause allergic reactions (possibly delayed).

4.5        Interaction with other Medicinal Products and other forms of Interaction

Due to the pharmacokinetic, pharmacodynamic and tolerance profile of cetirizine, no interactions are expected with this antihistamine. Neither the pharmacodynamic nor significant pharmacokinetic interaction was reported in drug-drug interactions studies performed, notably with pseudoephedrine or theophylline (400 mg/day).

The extent of absorption of the cetirizine is not reduced with food, although the rate of absorption is decreased.

4.6        Pregnancy and Lactation

Pregnancy

For cetirizine very rare clinical data on exposed pregnancies are available. Animal studies do not indicate direct or indirect harmful effects with respect to pregnancy, embryonal/fetal development, parturition or postnatal development. Caution should be exercised when prescribing to pregnant women.

Lactation

Cetirizine is excreted in human milk at concentrations representing 0.25 to 0.90 those measured in plasma, depending on sampling time after administration. Therefore, caution should be exercised when prescribing cetirizine to lactating women.

4.7        Effects on Ability to Drive and Use Machines

Objective measurements of driving ability, sleep problems and assembly line performance have not demonstrated any clinically relevant effects at the recommended dose of 10 mg.

Patients intending to drive, or engage in potentially hazardous activities or operating machinery should not exceed the recommended dose and should take their response to the medicinal product into account.

In sensitive patients, concurrent use with alcohol or other CNS depressants may cause additional reductions in alertness and impairment of performance.

4.8        Undesirable Effects

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 drug.

Clinical trials

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 reactions were reported for cetirizine 10 mg in the placebo-controlled trials at rates of 1.0% or greater:

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.

Adverse reactions at rates of 1% or greater in children aged from 6 months to 12 years, included in placebo-controlled clinical trials are:

Post-marketing experience

In addition to the adverse reactions reported during clinical studies and listed above, the following undesirable effects have been reported in post-marketing experience.

Undesirable effects are described according to MedDRA System Organ Class and by estimated frequency based on post-marketing experience.

Frequencies are defined as follows: 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

Psychiatric disorders

Uncommon:      agitation

Rare:    aggression, confusion, depression, hallucination, insomnia

Very rare:          tics

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

Cardiac disorders

Rare:    tachycardia

Gastro-intestinal disorders

Uncommon:      diarrhea

Hepatobiliary disorders

Rare:    hepatic function abnormal (increased transaminases, alkaline phosphatase, γ-GT and bilirubin)

Skin and subcutaneous tissue disorders

Uncommon:      pruritus, rash

Rare:    urticaria

Very rare:          angioneurotic oedema, fixed drug eruption

Renal and urinary disorders

Very rare:          dysuria, enuresis

General disorders and administration site conditions

Uncommon:      asthenia, malaise

Rare:    oedema

Investigations

Rare:    weight increased

5.1        Pharmacodynamic Properties

Pharmacotherapeutic group: Piperazine derivatives, ATC code: R06A E07

Cetirizine a 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.

In addition to its anti-H₁ effect, cetirizine displays an anti-allergic activities: at a dose of 10 mg once or twice daily, it inhibits the late phase recruitment of eosinophils, in the skin and conjunctiva of atopic subjects submitted to allergen challenge.

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 in the skin but this correlation with efficacy has not  been established.

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 a treatment with cetirizine is stopped after repeated administration, the skin recovers its normal reactivity to histamine within 3 days.

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 do 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 improves the quality of life of patients with perennial and seasonal allergic rhinitis.

5.2        Pharmacokinetic Properties

The steady- state peak plasma concentrations of approximately 300 ng/ml is achieved within 1.0 ± 0.5 h. No accumulation is observed for cetirizine following daily doses of 10 mg for 10 days. The distribution of pharmacokinetic parameters such as peak plasma concentration (C_max) and area under curve (AUC), is unimodal in volunteers.

The extent of absorption of cetirizine is not reduced with food, although the rate of absorption is decreased. The extent of bioavailability is similar whether the cetirizine its given as a solution, capsules or tablet.

The apparent volume of distribution is 0.50 l/kg. The plasma protein binding of cetirizine is 93 ± 0.3 %. Cetirizine does not modify the protein binding of warfarin.

Cetirizine does not undergo extensive first pass metabolism, approximately two thirds of the dose are excreted unchanged in urine. The terminal half-life is approximately 10 hours.

Cetirizine exhibits linear kinetics over the range of 5 to 60 mg.

Special populations:

Elderly: Following a single 10 mg oral dose the half-life increased by about 50 % and clearance decreased by 40 % in 16 elderly subjects compared to the normal subjects. The decrease in cetirizine clearance in these elderly volunteers appeared to be related to their decreased renal function.

Children, infants and toddlers: The half-life of cetirizine was about 6 hours in children aged 6-12 years and 5 hours in children 2-6 years. In infants and toddlers aged 6 to 24 months its reduced to 3.1 hours.

Renal impaired patients: The pharmacokinetics of the drug were similar in patients with mild impairment (creatinine clearance < 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 normal patients. Cetirizine was poorly cleared by haemodialysis. A dosing adjustment is necessary in patients with moderate or severe renal impairment (see section 4.2).

Hepatically impaired patients: 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 hepatic impairment patients if concomitant renal impairment is present.

5.3        Preclinical Safety Data

Non-clinical data revealed no special hazard for humans based on conventional studies of safety pharmacology, repeated dose toxicity, genotoxicity, carcinogenic potential, toxicity to reproduction.