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Am Fam Physician. 2003;68(10):2015-2016

Synopsis: Desloratadine (Clarinex) is the orally active metabolite of the nonsedating histamine-1 (H1) receptor antagonist loratadine (Claritin). It is indicated for seasonal and perennial allergic rhinitis and chronic idiopathic urticaria in patients 12 years of age and older.

NameStarting dosageDose formsMonthly cost*
Desloratadine (Clarinex)Adults and children 12 years of age: 5 mg orally daily5-mg tablets$67
Renal/hepatic impairment: 5 mg orally every other day

Safety: There are no major safety issues associated with desloratadine. It does not have any adverse cardiovascular effects or cause the heart conduction changes that have occurred with other second-generation antihistamines. Desloratadine is category C in pregnancy, and passes through the milk during breastfeeding. Loratadine is minimally excreted in the breast milk (<0.1 percent) after oral doses.1 While this may indicate safety with desloratadine, confirmatory studies are needed. The manufacturer recommends that women discontinue breastfeeding if they choose to take desloratadine.

Tolerability: Desloratadine is well tolerated. The type and number of side effects associated with desloratadine are similar to those associated with placebo. The most common adverse events are headache, fatigue, and dry mouth, which occur in 2 to 3 percent of people.

Effectiveness: Desloratadine decreases both nasal symptoms (rhinorrhea, congestion, nasal itching, and sneezing) and nonnasal symptoms (itchy, watery, red eyes, and itchy ears) in patients with seasonal allergic rhinitis. The benefit is statistically significant but not very impressive clinically: approximately 0.25 points on a 3-point scale compared with placebo in both categories.2,3 Desloratadine also is effective for chronic idiopathic urticaria.4 Over six weeks, desloratadine reduced pruritus symptom scores by 74 percent compared with 48.7 percent for placebo (P<.001). A well-designed randomized crossover trial found that desloratadine is no more effective than fexofenadine (Allegra) at usual therapeutic dosages in relieving symptoms of seasonal allergic rhinitis.5

Price: A one-month supply of desloratadine costs between $60 and $70, similar to the cost of other prescription antihistamines such as fexofenadine and cetirizine (Zyrtec). This is about twice the cost of nonprescription loratadine and is much more expensive than other nonprescription antihistamines.

Simplicity: Desloratadine is available in 5-mg tablets. The daily dose in patients older than 12 years is 5 mg once a day. Patients with renal or hepatic impairment should take 5 mg every other day.

Bottom line: Desloratadine is somewhat effective for the treatment of seasonal allergic rhinitis and may decrease nasal congestion. It also is effective for chronic urticaria. Desloratadine is similar in effectiveness to fexofenadine and would be expected to produce results similar to loratadine and other nonsedating antihistamines. 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.

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