Cetirizine + Pseudoephedrine

Oral
Allergic rhinitis

1 tab once daily.

Cetirizine + Pseudoephedrine extended-release: May be taken with or without food. Swallow whole, do not chew/crush.

Severe hypertension, severe coronary artery disease, uncontrolled hyperthyroidism, increased IOP, urinary retention, severe arrhythmia. Concomitant use with or within 2 weeks of discontinuing MAOI treatment.

Patient with CV disease (e.g. mild or controlled hypertension), diabetes mellitus, thyroid dysfunction. Renal and hepatic impairment. Children and elderly. Pregnancy and lactation.

Significant: CNS depression (e.g. sedation, drowsiness, fatigue); rebound pruritus (usually after long-term use).
Cardiac disorders: Tachycardia.
Ear and labyrinth disorders: Vertigo.
Gastrointestinal disorders: Xerostomia, nausea.
General disorders and administration site conditions: Asthenia.
Nervous system disorders: Dizziness, headache.
Psychiatric disorders: Insomnia, nervousness.
Respiratory, thoracic and mediastinal disorders: Pharyngitis, epistaxis.

PO: C

This drug may cause drowsiness, if affected, do not drive or operate machinery.

Symptoms: Cetirizine: Drowsiness. Pseudoephedrine: Irritability, tremor, convulsions, palpitations, hypertension, difficulty in micturition, tachycardia, arrhythmia, CNS depression or stimulation. Management: Symptomatic and supportive treatment. Perform gastric lavage if indicated. After vomiting, activated charcoal may be used for the remaining drug in the stomach. Monitor vital parameters regularly. Catheterisation of the bladder may be needed. Elimination of pseudoephedrine may be increased by acid diuresis or dialysis. Administer α-blockers to treat hypertension and β-blockers for tachycardia. Diazepam may be administered to control seizures.

Cetirizine: May increase drowsiness with CNS depressants (e.g. sedatives, tranquillisers).
Pseudoephedrine: Increased ectopic pacemaker activity with digitalis. Increased rate of absorption with antacids. Decreased rate of absorption with kaolin. Concomitant use with other sympathomimetic agents (e.g. decongestants, TCAs, appetite suppressants, amphetamine-like psychostimulants) may cause elevated blood pressure. May reduce the effect of antihypertensive drugs that interfere with sympathetic activity (e.g. guanethidine, reserpine, methyldopa, α- and β-adrenergic blockers).
Potentially Fatal: Pseudoephedrine: May increase the risk of hypertensive crisis with MAOIs.

May increase drowsiness with alcohol.

Cetirizine: May inhibit allergy skin tests.

Description:
Mechanism of Action: Cetirizine is a 2nd generation antihistamine. It selectively competes with histamine for H₁-receptor sites on effector cells in the respiratory tract, blood vessels and gastrointestinal tract.
Pseudoephedrine is a sympathomimetic agent. It directly activates α-adrenergic receptors of respiratory mucosa leading to vasoconstriction. It also stimulates β-adrenergic receptors leading to bronchial smooth muscle relaxation and increased heart rate and contractility.
Pharmacokinetics:
Absorption: Cetirizine: Rapidly and almost completely absorbed. Time to peak plasma concentration: Approx 1 hour.
Pseudoephedrine: Rapidly and completely absorbed. Time to peak plasma concentration: 3.8-6.1 hours.
Distribution: Enters breast milk.
Cetirizine: Volume of distribution: Approx 0.5 L/kg. Plasma protein binding: 93%.
Metabolism: Cetirizine: Limited metabolism in the liver.
Pseudoephedrine: Metabolised via N-demethylation to norpseudoephedrine.
Excretion: Cetirizine: Via urine (70%; 50% as unchanged drug); faeces (10%). Elimination half-life: 8 hours.
Pseudoephedrine: Via urine (43-96% as unchanged drug, 1-6% as norpseudoephedrine). Elimination half-life: 3-6 hours (pH of 5); 9-16 hours (pH of 8).

Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 2678, Cetirizine. https://pubchem.ncbi.nlm.nih.gov/compound/Cetirizine. Accessed Sept. 24, 2024.

Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 7028, Pseudoephedrine. https://pubchem.ncbi.nlm.nih.gov/compound/Pseudoephedrine. Accessed July 26, 2024.

Store below 30°C.

Antihistamines & Antiallergics

R01BA52 - pseudoephedrine, combinations ; Belongs to the class of systemic sympathomimetic preparations used as nasal decongestants.

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