Levocetirizine

Table of contents

• What is levocetirizine?
• How does levocetirizine work?
• Which conditions is it used or studied for?
• How is levocetirizine given?
• What do the clinical trials show?
• What side effects are known?

What is levocetirizine?

Levocetirizine is a second-generation antihistamine, specifically a histamine H1-receptor antagonist.^[2] It is the active enantiomer of cetirizine, meaning it is the specific chemical form responsible for the antihistamine effect. The substance is also known as levocetirizine dihydrochloride, the salt form used in tablets.^[2] Levocetirizine is an authorised medicine, with initial U.S. approval dating back to 1995, and is available as a prescription drug.^[2] Its ATC code is R06AE09, placing it among other antihistamines for systemic use.^[3]

How does levocetirizine work?

Levocetirizine works by blocking histamine H1 receptors. Histamine is a substance released during allergic reactions, and when it binds to H1 receptors it causes symptoms such as itching, sneezing, runny nose, and hives. By occupying these receptors, levocetirizine prevents histamine from triggering those symptoms.^[2] Because it is a second-generation antihistamine, it is designed to cause less drowsiness than older antihistamines, although the label still lists somnolence among possible effects.^[2]

Which conditions is it used or studied for?

• Perennial allergic rhinitis — year-round allergy symptoms such as sneezing, itchy and runny nose caused by indoor allergens like dust mites or pet dander.^[2]
• Chronic idiopathic urticaria — long-lasting hives with no identified cause, where levocetirizine treats the uncomplicated skin manifestations.^[2]
• IgA nephropathy — in one Phase 3 clinical trial, levocetirizine is not the treatment being studied but is given as a premedication to help manage possible infusion-related reactions in participants receiving felzartamab.^[1]

How is levocetirizine given?

Levocetirizine is given by mouth. It is available as immediate-release, breakable film-coated tablets of 5 mg.^[2] A sugar-free orodispersible tablet form of 5 mg also exists, which dissolves in the mouth without water.^[3] In the IgA nephropathy trial, levocetirizine is administered orally at a dose of 2.5 mg as part of a premedication regimen before felzartamab infusion.^[1] The product information describes a 5 mg once-daily dose in the evening for adults and children 12 years and older with chronic idiopathic urticaria, and 2.5 mg once daily for children aged 6 to 11 years.^[2]

What do the clinical trials show?

One clinical trial in the EU Clinical Trials Information System lists levocetirizine: a Phase 3 study called PREVAIL (NCT06935357) in adults with IgA nephropathy.^[1] Levocetirizine is not the main study drug in this trial; the trial investigates felzartamab infusions compared with placebo. Levocetirizine appears among several premedications, including paracetamol, diphenhydramine, famotidine, methylprednisolone, and other antihistamines such as cetirizine, loratadine, desloratadine, and fexofenadine.^[1]

The trial is authorised, meaning it has received regulatory approval to proceed, and plans to enrol 660 participants.^[1] The primary outcome is the percent change from baseline in proteinuria, measured by the urine protein-to-creatinine ratio (UPCR). Proteinuria means protein in the urine and is a key marker of kidney damage in IgA nephropathy.^[1] Because levocetirizine is used only as a premedication in this study, the trial does not measure levocetirizine's own effectiveness in IgA nephropathy.

What side effects are known?

The prescribing information for levocetirizine dihydrochloride tablets lists warnings and precautions, including a risk of new onset pruritus, or itching, after discontinuation of the medicine.^[2] The label also mentions somnolence, or sleepiness, as a possible effect, consistent with its class of antihistamines.^[2] The product is contraindicated in patients with a known hypersensitivity to levocetirizine, any of its ingredients, or to cetirizine, and in patients with end-stage renal disease with creatinine clearance below 10 mL per minute.^[2] The supplementary sources provided do not include a full list of adverse reactions from clinical experience, so only these label statements are reported here.