Tablet: Each film-coated tablet contains: Cetirizine Hydrochloride 10 mg.
Oral solution: Each mL contains Cetirizine Dihydrochloride 1 mg.
Oral drops: Each mL contains: Cetirizine Dihydrochloride 2.5 mg.
Cetirizine hydrochloride is a piperazine derivative and a metabolite of hydroxyzine. It competes reversibly with histamine to block the histamine (H1) receptor sites. Cetirizine hydrochloride is considered a long-acting non-sedating antihistamine and has some mast-cell stabilizing activity.
Pharmacology: Cetirizine hydrochloride is a long-acting antihistamine causing little or no drowsiness. It does not demonstrate any antimuscarinic activity. This drug competes reversibly with histamines which are released from mast cells. Once bound to H1 receptor sites in the tissues, cetirizine inhibits histamine-induced allergic reactions by blocking eosinophil infiltration to the site of allergen-induced cutaneous reactions.
Pharmacokinetics: Upon oral administration, cetirizine hydrochloride is rapidly absorbed from the gastrointestinal tract. Peak plasma concentration (Cmax) is achieved after an hour. Cmax of the drug may be delayed by food. However, it does not change the amount of drug absorbed. It has higher affinity to peripheral rather than central histamine H1 receptors and does not penetrate the blood-brain barrier to a significant extent.
Cetirizine hydrochloride is highly protein bound (93%) and has a half life of approximately 11 hours in adults. This is mainly excreted in the urine as unchanged drug.
Cetirizine has been detected in breast milk.
For the treatment of perennial rhinitis, seasonal allergic rhinitis, chronic idiopathic urticaria and allergic conjunctivitis.
Cetirizine hydrochloride is given orally at 10 mg per day or 5 mg twice a day for adults and children 6 years and older. There was no additional benefit seen in increasing dose of cetirizine hydrochloride to 20 mg.
In children 2 to 5 years, cetirizine hydrochloride may be given at 5 mg per day given as one dose or 2.5 mg twice a day given every after twelve hours.
For children ages 6 months to 2 years with perennial allergic rhinitis and chronic urticaria, the initial dose is 2.5 mg per day. This may be increased to a maximum of 5 mg per day given two times per day.
Or as prescribed by the physician.
For patients with hepatic and renal impairment, the dose should be reduced to half their usual dose per day.
In managing seasonal rhinitis, it is recommended that cetirizine hydrochloride be given at the beginning of hay fever season when pollens are still few.
Cetirizine hydrochloride may be administered with or without food as it will not affect absorption of the drug.
Oral drops: Adults & children >12 years: 20 drops once daily (eq. to 1 mL).
Children 6-12 years: 20 drops (eq. to 1 mL) once daily or as divided doses, 10 drops (eq. to 0.5 mL) on the morning and 10 drops (eq. to 0.5 mL) in the evening.
2-5 years: 10 drops (eq. to 0.5 mL) once daily or as divided doses, 5 drops (eq. to 0.25 mL) on the morning and 5 drops (eq. to 0.25 mL) in the evening.
6 months to 2 years: 5 drops (eq. to 0.25 mL) once daily or as divided doses, 2.5 drops (eq. to 0.125 mL) on the morning and 2.5 drops (eq. to 0.125 mL) in the evening.
Oral dose: Overdose may be fatal especially in infants and children. It is associated with antimuscarinic, extrapyramidal, gastrointestinal and CNS effects.
Infants and Children: CNS stimulation predominates over CNS depression, causing ataxia, excitements tremors, psychoses, hallucinations, convulsions and hyperpyrexia. Deepening coma and cardiorespiratory collapse may follow.
Adults: CNS depressions is more common with drowsiness, coma and convulsions progressing to respiratory failure or possibly cardiovascular collapse.
Hypersensitivity to antihistamines. History of unusual severe reactions such as excessive sedation or CNS stimulation. Prostatic hypertrophy, narrow-angle glaucoma. Neonates and preterm/premature infants.
Oral soln: Reduced dosage is recommended for patients with renal impairment.
Oral drops: Cetirizine should not be given to premature infants or neonates; this group of patients have an increased susceptibility to antimuscarinic effects. Elderly patients are also susceptible to affect such as antimuscarinic effect, sedation and hypotension. Cetirizine may cause drowsiness, patients are advised that they should not drive or operate machinery. Patients should avoid alcoholic drink. Cautions are suggested to patients with epilepsy and severe cardiovascular disorders. Reduced dosage is recommended for patients with renal impairment.
Use in Pregnancy: Some antihistamine has been associated with fetal abnormalities when taken during pregnancy but no adverse effects have been reported from animal studies. As with other drugs, the use of Cetirizine in pregnancy should be avoided.
Oral drops: Use in Pregnancy: Some antihistamine have been associated with fetal abnormalities when taken during pregnancy but no adverse effects have been reported from animal studies. As with other drugs, the use of Cetirizine in pregnancy should be avoided.
Cetirizine hydrochloride, though considered as a 'non-sedating' anti-histamine, was found to cause drowsiness.
Recurrent acute hepatitis developed in one patient taking cetirizine hydrochloride for control of seasonal allergic rhinitis.
Other adverse effects associated with the use of cetirizine hydrochloride are irritability, insomnia, somnolence, fatigue, dry mouth, pharyngitis, dizziness, headache, abdominal pain, cough, diarrhea, epistaxis, bronchospasm, nausea and vomiting and hypersensitivity manifested by urticaria and fixed drug eruptions.
Although cetirizine hydrochloride has low potential for severe hepatotoxicity, the possibility of developing autoimmune-mediated hepatotoxicity should be considered when administering the drug. A patient under long-term treatment with cetirizine hydrochloride for atopic dermatitis was reported to have developed life-threatening hepatitis.
The most common adverse effect of cetirizine is sedation. Other adverse effects including hypotension, tinnitus, headache, dizziness, paresthesias, gastrointestinal disturbances and blood disorders.
Sedation may be enhanced upon concomitant use of antihistamines in general with central nervous system depressants such as barbiturates, alcohol, hypnotic, opioid analgesics, anxiolytic sedatives and neuroleptics.
The use of cetirizine hydrochloride with drugs that inhibit the cytochrome P-450 microsomal enzymes such as azithromycin, erythromycin and ketoconazole, did not cause clinically significant changes.
Oral drops: Sedative interactions apply to a lesser extent with the non-sedating antihistamines; they do not appear to potentiate the effects of alcohol, but it should be avoided in excess. Sedating antihistamines have an additive antimuscarinic action with other antimuscarinic drugs, such as atropine and some antidepressants (both tricyclics and MAOIs).
Store at temperatures not exceeding 30°C.
Oral drops: Shake well before use.
R06AE07 - cetirizine ; Belongs to the class of piperazine derivatives used as systemic antihistamines.
FC tab/Oral soln:Rx; Oral drops:Non-Rx
FC tab 10 mg x 100's. Oral soln 1 mg/mL x 30 mL, 60 mL. Oral drops 2.5 mg/mL x 15 mL.