hydroxyzine hydrochloride: clinical use

Prescribing considerations

• Assess acquired or congenital QT prolongation, cardiovascular disease, bradycardia, electrolyte disturbance, family history of sudden cardiac death and interacting medicines before prescribing.
• Use in older people is not recommended because elimination is reduced and anticholinergic adverse effects are more likely.
• Review renal and hepatic function, sedation risk, antimuscarinic burden and the need to drive or operate machinery.
• Account for interference with allergy skin and methacholine testing.

Contraindications and cautions

• Hypersensitivity to hydroxyzine, cetirizine, other piperazine derivatives, aminophylline, ethylenediamine or an excipient.
• Known acquired or congenital QT prolongation, or specified QT-risk factors including cardiovascular disease, significant hypokalaemia or hypomagnesaemia, significant bradycardia, family history of sudden cardiac death or concomitant QT-prolonging medicines.
• Previous serious antihistamine-induced bronchopulmonary reaction in a person with asthma.
• Porphyria.
• Pregnancy and breastfeeding under the selected product licence.
• Relevant rare hereditary disorders of lactose metabolism.

Monitoring

• Monitor for excessive sedation, impaired cognition, paradoxical excitation and antimuscarinic effects.
• Reassess promptly if palpitations, syncope, breathlessness or other possible arrhythmia symptoms develop.
• Consider ECG and electrolyte assessment where cardiac risk is uncertain or potentially reversible risk factors are present.
• Monitor clinically for accumulation or adverse effects in renal or hepatic impairment.

Clinical pharmacology

Hydroxyzine is a first-generation piperazine H1-receptor antagonist that crosses the blood–brain barrier. It has sedative and antimuscarinic properties, is metabolised mainly in the liver through alcohol dehydrogenase and CYP3A4/5 pathways, and forms the active metabolite cetirizine, which is predominantly renally eliminated.

Formulation and product differences

• The selected product is a white, circular, biconvex film-coated oral tablet.
• It contains lactose monohydrate and is supplied in blister packaging.
• Products from different manufacturers may vary in excipients, tablet markings and pack sizes; check the product-specific information.

Tablet

Route: Oral

Strengths: 10 mg, 25 mg