Levocetirizine

Levocetirizine is the active enantiomer (levorotatory form) of cetirizine and belongs to the second generation of antihistamines. It is used for allergic rhinitis (hay fever), perennial rhinitis, and chronic idiopathic urticaria.

At a dose of only 5 mg, levocetirizine achieves the same efficacy as 10 mg of cetirizine, but with a side effect profile that tends to be more favorable. Levocetirizine is available as a generic (e.g., Levocetirizin-ratiopharm®, Levocetirizin HEXAL®) and under the brand name Xusal®.

It acts very quickly.

Levocetirizine selectively blocks H1 histamine receptors:

Mechanism of action:

• High-affinity blockade of peripheral H1 receptors
• Twice the receptor affinity compared with cetirizine
• Inhibits histamine-mediated vasodilation, edema formation, and itching
• Additional anti-inflammatory properties

Pharmacokinetics:

• Rapid absorption: onset of action after 30–60 minutes
• High oral bioavailability (> 85%)
• Half-life: 7–10 hours
• Duration of action: over 24 hours with a single dose

Advantages:

• Fastest onset of action among oral antihistamines
• High efficacy at a low dose
• Less sedation than cetirizine

Levocetirizine is suitable for:

• Adults and children aged 6 years and older with seasonal allergic rhinitis
• Patients with perennial (year-round) allergic rhinitis
• Chronic idiopathic urticaria

Particularly recommended for:

• Patients who need very rapid symptom relief
• When cetirizine 10 mg causes too much tiredness (levocetirizine 5 mg is often better tolerated)
• Severe allergic symptoms that require a potent antihistamine

Not suitable:

• Children under 2 years of age
• Severe renal insufficiency (creatinine clearance < 10 ml/min)
• Hypersensitivity to levocetirizine, cetirizine, or hydroxyzine

Adults and adolescents aged 12 years and older:

• 5 mg once daily (one film-coated tablet)

Children:

• 6–11 years: 5 mg once daily
• 2–5 years: 1.25 mg twice daily (as drops)

Available dosage forms:

• 5 mg film-coated tablets
• Oral drops (for children)

Dose adjustment in renal insufficiency:

• Mild (CrCl 50–79): 5 mg daily
• Moderate (CrCl 30–49): 5 mg every 2 days
• Severe (CrCl 10–29): 5 mg every 3 days
• Dialysis: contraindicated

How to take:

• Once daily, preferably in the evening (if mild tiredness occurs)
• Regardless of meals (food slightly delays absorption)
• Swallow the film-coated tablet whole with water, without chewing
• Drops directly into the mouth or on a spoon

Important notes:

• Take regularly for optimal effect
• If tiredness occurs: move intake to the evening
• Alcohol can increase the sedative effect – use caution
• Do not take together with other sedating medications

Duration of use:

• Seasonal allergy: during the pollen season
• Perennial allergy: year-round as recommended by a doctor
• Urticaria: until symptom-free

Levocetirizine must not be taken in cases of:

• Hypersensitivity to levocetirizine, cetirizine, or hydroxyzine
• Severe renal insufficiency (creatinine clearance < 10 ml/min)
• Renal insufficiency requiring dialysis

Caution in cases of:

• Impaired kidney function (dose adjustment required)
• Epilepsy or increased susceptibility to seizures
• Concurrent alcohol consumption
• Predisposition to urinary retention (e.g., spinal cord lesion, prostatic hyperplasia)

Pregnancy and breastfeeding: There are insufficient data on use during pregnancy. It passes into breast milk. During pregnancy and breastfeeding, use only after consulting a doctor.

Common (1–10%):

• Headache
• Drowsiness/tiredness (less than with cetirizine)
• Dry mouth
• Fatigue

Uncommon (0.1–1%):

• Abdominal pain

Frequency not known:

• Nausea
• Dizziness
• Visual disturbances
• Palpitations
• Weight gain
• Hypersensitivity reactions
• Seizures
• Liver function disorders
• Aggression, agitation

Note: Compared with cetirizine 10 mg, the rate of sedation with levocetirizine 5 mg is somewhat lower.

Caution when taken at the same time as:

• Alcohol (increased sedation possible)
• Other CNS depressants (benzodiazepines, opioids)
• Theophylline (slight inhibition of levocetirizine clearance)
• Ritonavir (may increase levocetirizine levels)

No relevant interaction with:

• Pseudoephedrine
• Food (slight delay, but no loss of effect)
• Medications dependent on CYP enzymes (minimal CYP metabolism)

Note: Levocetirizine has a relatively favorable interaction profile, as it is hardly metabolized by the liver and is mainly excreted by the kidneys.