Levocetirizine
Levocetirizine, sold under the brand name Xyzal among others, is a second-generation antihistamine used for the treatment of allergic rhinitis (hay fever) and long term hives of unclear cause. It is less sedating than older antihistamines. It is taken by mouth.Common side effects include sleepiness, dry mouth, cough, vomiting, and diarrhea. Use in pregnancy appears safe but has not been well studied and use when breastfeeding is of unclear safety. It is classified as a second-generation antihistamine and works by blocking histamine H1-receptors.Levocetirizine was approved for medical use in the United States in 2007. It is available as a generic medication. In 2019, it was the 193rd most commonly prescribed medication in the United States, with more than 2 million prescriptions.

Medical uses
Levocetirizine is used for allergic rhinitis. This includes allergy symptoms such as watery eyes, runny nose, sneezing, hives, and itching.

Side effects
Levocetirizine is referred to as a non-sedating antihistamine as it does not enter the brain in significant amounts and is therefore unlikely to cause drowsiness. Cardiac safety with repolarization may be better than some other antihistamines, as levocetirizine does not significantly prolong the QT interval in healthy individuals. However, some people may still experience some slight sleepiness, headache, mouth dryness, lightheadedness, vision problems (mainly blurred vision), palpitations and fatigue.

Pharmacology
Levocetirizine is an antihistamine. It acts as an inverse agonist that decreases activity at histamine H1 receptors. This in turn prevents the release of other allergy chemicals and increases the blood supply to the area, providing relief from the typical symptoms of hay fever. Levocetirizine, (R)-(-)-cetirizine, is essentially a chiral switch of (±)-cetirizine. This enantiomer, the eutomer, is more selective and less sedative and the (S)-counterpart, the distomer, is inactive.

Chemistry
Chemically, levocetirizine is the active levorotary enantiomer of cetirizine, also called the l-enantiomer of cetirizine. It is a member of the diphenylmethylpiperazine group of antihistamines.

History
Levocetirizine was first launched in 2001 by the Belgian pharmaceutical company UCB (Union Chimique Belge).

Society and culture
Availability
On 31 January 2017, the Food and Drug Administration approved an over-the-counter preparation. Levocetirizine had previously received authorization by the FDA as a prescription drug in 2007, having already been brought to market throughout much of Europe. In India, a prescription-only drug containing levocetirizine hydrochloride and montelukast is sold as Crohist MK.

Brand names
Preparations of levocetirizine are sold under the following brand names:

Xyzal  in Australia, Austria, Bulgaria, Croatia, Cyprus, Czech Republic, Finland, France, Hungary, India, Ireland (also Rinozal), Italy, Japan, Lithuania, Netherlands, Poland, Portugal, Romania, Taiwan, Thailand, Turkey, The Philippines, Serbia, Singapore, Slovakia, Slovenia, South Africa, Spain, Switzerland and UK. On May 25, 2007, the United States Food and Drug Administration approved Xyzal, where it is co-marketed by Sanofi-Aventis.
Zobral in Cyprus
Levobert in India
Xusal in Germany and Mexico
Xozal in Greece
Degraler in Chile
Allevo in Egypt
Zilola, Histisynt, and Xyzal (UCB) in Hungary
Alcet, Curin, and Seasonix in Bangladesh
Vozet and Uvnil in India
T-Day Syrup in Pakistan
Curin in Nepal.
Zenaro in the Czech Republic and Slovakia
Xuzal and Zival in Chile
Cezera, Levosetil, Robenan, and Xyzal in Serbia.
Rinozal and Xyzal in Ireland

References
External links
"Levocetirizine". Drug Information Portal. U.S. National Library of Medicine.
"Levocetirizine dihydrochloride". Drug Information Portal. U.S. National Library of Medicine.