Loratadine

Loratadine is a drug used to treat allergies. It is marketed by Schering-Plough under several trade names such as Claritin®, Clarityn® or Claratyne® depending on the market, and by Wyeth as Alavert. It is also available as a generic. Its active metabolite, desloratadine, is also on the market, though loratadine itself is the only drug of its class available over the counter (at least in the US and UK) as of 2005. It is sometimes combined with pseudoephedrine to add a decongestant aspect to the treatment, making it somewhat useful for colds as well as allergies.

Available forms

Loratadine is available as tablets and oral suspension.

Mechanism of action

Loratadine is a tricyclic antihistamine, which has a selective and peripheral H₁-antagonist action. It has a long-lasting effect and does not cause drowsiness because it does not readily enter the central nervous system.

Pharmacokinetics

Loratadine is rapidly absorbed from the gastro-intestinal tract and it has rapid first-pass hepatic metabolism . Loratadine is almost totally bound to plasma proteins. Its metabolite, desloratadine (descarboethoxyloratadine), is also active, but binds to plasma proteins only moderately. The half-life of loratadine is on average 8 hours, and its metabolite's 28 hours. About 40% is excreted as conjugated metabolites into the urine and similar amount into the feces. Traces of unmetabolised loratadine can be found in the urine.

Recommended dosage

10mg every 24 hours, not to exceed 10mg every 24 hours. (From product packaging for Claritin 24 Hour Tablets.)

Side effects

Most common side-effects are fatigue, drowsiness, dry mouth, headache, and gastrointestinal disturbances.

References