Levocetirizine

Levecetirizine is a drug from the group of antihistamines. It belongs to the second generation of H₁ antihistamines, which are less sedating than those of the first generation. It is used for allergic reactions such as hay fever, or for skin rashes of unknown cause. Levocetirizine is taken perorally.

From a chemical point of view, levocetirizine is the (R)-enantiomer of the antihistamine cetirizine. Levocetirizine has higher selectivity for the H1 receptor than cetirizine, resulting in a more favorable side effect profile for patients. It was first approved in Europe in the early 2000s.

Pharmacodynamics

Levocetirizine is a highly selective H₁ receptor antagonist. It binds to the H₁-receptor, preventing the binding of its endogenous ligand histamine. The failure to bind histamine reduces typical symptoms of allergic reactions.

Pharmacokinetics

Levocetirizine has a very broad therapeutic range and a long duration of action, making once-daily administration sufficient. Plasma protein binding of the substance is about 96%. About 85% of the administered oral dose is excreted unchanged. The remaining 15% is metabolized by the liver to a variety of metabolites and excreted in the urine. The average half-life of levocetirizine is approximately 7 hours.

Drug Interactions

There are no known significant interactions with other drugs.

Adverse effects:

• Mild drowsiness or fatigue
• Headache
• Dry mouth
• Drowsiness
• Visual disturbances (mainly blurred vision)
• Palpitations

Pregnancy and lactation

Use in pregnancy appears to be safe, but is not considered well studied. The safety of use in lactation is unclear.

Toxicological Data

The maximum non-lethal dose in mice and rats is 240mg/kg.