Loratadiini

Loratadiini, the Italian name for loratadina, is a second-generation oral antihistamine used to relieve symptoms of allergic rhinitis, conjunctivitis, and chronic idiopathic urticaria. It acts as a selective antagonist of peripheral histamine H1 receptors, reducing sneezing, itching, runny nose, and hives. Compared with first-generation antihistamines, loratadina is designed to cause less drowsiness because it crosses the blood–brain barrier to a lesser extent.

Pharmacokinetics and metabolism: after oral administration, loratadina is rapidly absorbed and reaches peak plasma levels within one to three hours; it is extensively metabolized in the liver by cytochrome P450 enzymes (mainly CYP3A4 and CYP2D6) to desloratadina, an active metabolite. The drug's elimination half-life supports once-daily dosing in most adults; desloratadina has a longer half-life, contributing to prolonged effect.

Formulations and dosing: available as tablets and rapidly disintegrating tablets for oral use, with dosing tailored to age and condition. It is commonly used for seasonal and perennial allergic rhinitis, conjunctivitis, and chronic urticaria.

Safety and regulation: adverse effects are generally mild and may include headache, fatigue, dry mouth, or somnolence in a minority of patients. Interactions with alcohol or other sedating drugs are possible, and caution is advised in significant liver impairment. Loratadina has a pregnancy safety profile of category B in many guidelines and is widely available over the counter in many countries.

History: loratadina was developed in the late 20th century and marketed under brand names such as Claritin; it became one of the first widely used second-generation antihistamines.