Loratadine (INN) is a second-generation H1 histamine antagonist drug used to treat allergies. Structurally, it is closely related to tricyclic antidepressants, such as imipramine, and is distantly related to the atypical antipsychotic quetiapine. Loratadine is marketed by Schering-Plough under several trade names (e.g., Claritin) and also by Shionogi in Japan. It is available as a generic drug and is marketed for its non-sedating properties. In a version named Claritin-D or Clarinase, it is combined with pseudoephedrine, a decongestant; this makes it useful for colds as well as allergies but adds potential side-effects of insomnia, anxiety, and nervousness. Contents [hide] 1 History 2 Indications 2.1 Forms 3 Cautions and contraindications 4 Adverse effects 5 Mechanism of action 6 Pharmacokinetics 7 Interactions 8 Legal status 9 References 10 External links  HistorySchering-Plough developed loratadine as part of a quest for a potential blockbuster drug: a nonsedating antihistamine. However, by the time Schering submitted the drug to the U.S. Food and Drug Administration (FDA) for approval, the agency had already approved a competitor's non-sedating antihistamine, terfenadine (trade name Seldane), and, therefore, put loratadine on a lower priority as a "me too" drug. Loratadine was eventually approved by the FDA in 1993. It accounted for 28% of Schering's total sales. The drug continued to be available only by prescription in the U.S. until it went off patent in 2002. It was then immediately approved for over-the-counter sales. Once it became an unpatented over-the-counter drug, the price dropped precipitously, and insurance companies no longer paid for it. In response, Schering launched an expensive advertising campaign to convince users to switch to desloratadine (descarboethoxyloratadine, trade name Clarinex), which is the active metabolite of loratadine. A 2003 study comparing the two drugs found that "There is no clinical advantage to switching a patient from loratadine to desloratadine. However, it may be an option for patients whose medical insurance no longer covers loratadine if the co-pay is less than the cost of the over-the-counter product." However, as of 2009, 10 mg loratadine tablets can be purchased relatively inexpensively, as generic manufacturers offer 120-day supplies for less than $25.  IndicationsLoratadine is indicated for the symptomatic relief of allergy such as hay fever (allergic rhinitis), urticaria (hives), and other skin allergies. For allergic rhinitis (hay fever), loratadine is effective for both nasal and eye symptoms: sneezing, runny nose, itchy or burning eyes. Loratadine could be also used to treat mild to moderate pain from headaches.