Side Effects of Clarinex (desloratadine)

Clarinex (desloratadine) is a long-acting antihistamine chemically similar to loratadine (Claritin) used to treat allergies and hives (chronic urticaria) in adults and children 12 years of age and older. 

Histamine is a chemical responsible for many of the signs and symptoms of allergic reactions, for example, swelling of the lining of the nose, sneezing, and itchy eyes. Histamine is released from histamine-storing cells (mast cells) and then attaches to other cells that have receptors for histamine. 

The attachment of the histamine to the receptors causes the cells to be "activated," releasing other chemicals which produce the effects that we associate with allergy. Clarinex blocks one type of receptor for histamine (the H1 receptor) and thus prevents activation of H1 receptor-containing cells by histamine. Clarinex does not readily enter the brain from the blood and, therefore, causes less drowsiness. 

Common side effects of Clarinex include

• headache,
• dizziness,
• nausea,
• weakness,
• sore throat,
• dry mouth,
• muscle pain,
• painful menstruation, and
• sleepiness.

Drug interactions of Clarinex include ketoconazole, erythromycin, azithromycin, fluoxetine, and cimetidine, which increase blood levels of Clarinex by reducing the elimination of Clarinex by liver enzymes. 

Clarinex has not been studied in pregnant women. Clarinex passes into breast milk and should be used with caution in women who are breastfeeding.

The most common side effects of desloratadine are:

• headache,
• dizziness,
• nausea,
• weakness,
• sore throat,
• dry mouth,
• muscle pain,
• painful menstruation, and
• sleepiness.

The following adverse reactions are discussed in greater detail in other sections of the label:

• Hypersensitivity reactions.

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice.

Adults And Adolescents

Allergic Rhinitis

• In multiple-dose placebo-controlled trials, 2834 patients ages 12 years or older received Clarinex Tablets at doses of 2.5 mg to 20 mg daily, of whom 1655 patients received the recommended daily dose of 5 mg.
• In patients receiving 5 mg daily, the rate of adverse events was similar between Clarinex and placebo-treated patients.
• The percent of patients who withdrew prematurely due to adverse events was 2.4% in the Clarinex group and 2.6% in the placebo group.
• There were no serious adverse events in these trials in patients receiving desloratadine.
• All adverse events that were reported by greater than or equal to 2% of patients who received the recommended daily dose of Clarinex Tablets (5 mg once daily), and that were more common with Clarinex Tablets than placebo, are listed in Table 1.

Table 1: Incidence of Adverse Events Reported by ≥2% of Adult and Adolescent Allergic Rhinitis Patients Receiving Clarinex Tablets

• The frequency and magnitude of laboratory and electrocardiographic abnormalities were similar in Clarinex and placebo-treated patients.
• There were no differences in adverse events for subgroups of patients as defined by gender, age, or race.

Chronic Idiopathic Urticaria

• In multiple-dose, placebo-controlled trials of chronic idiopathic urticaria, 211 patients ages 12 years or older received Clarinex Tablets and 205 received placebo.
• Adverse events that were reported by greater than or equal to 2% of patients who received Clarinex Tablets and that were more common with Clarinex than placebo were (rates for Clarinex and placebo, respectively):
  • headache (14%, 13%),
  • nausea (5%, 2%),
  • fatigue (5%, 1%),
  • dizziness (4%, 3%),
  • pharyngitis (3%, 2%),
  • dyspepsia (3%, 1%), and
  • myalgia (3%, 1%).

Pediatrics

• Two hundred and forty-six pediatric subjects 6 months to 11 years of age received Clarinex Oral Solution for 15 days in three placebo-controlled clinical trials.
• Pediatric subjects aged 6 to 11 years received 2.5 mg once a day, subjects aged 1 to 5 years received 1.25 mg once a day, and subjects 6 to 11 months of age received 1.0 mg once a day.
• In subjects 6 to 11 years of age, no individual adverse event was reported by 2 percent or more of the subjects.
• In subjects 2 to 5 years of age, adverse events reported for Clarinex and placebo in at least 2 percent of subjects receiving Clarinex Oral Solution and at a frequency greater than placebo were fever (5.5%, 5.4%), urinary tract infection (3.6%, 0%) and varicella (3.6%, 0%).
• In subjects 12 months to 23 months of age, adverse events reported for the Clarinex product and placebo in at least 2 percent of subjects receiving Clarinex Oral Solution and at a frequency greater than placebo were
  • fever (16.9%, 12.9%),
  • diarrhea (15.4%, 11.3%),
  • upper respiratory tract infections (10.8%, 9.7%),
  • coughing (10.8%, 6.5%),
  • appetite increased (3.1%, 1.6%),
  • emotional lability (3.1%, 0%),
  • epistaxis (3.1%, 0%),
  • parasitic infection (3.1%, 0%),
  • pharyngitis (3.1%, 0%),
  • rash maculopapular (3.1%, 0%).
• In subjects 6 months to 11 months of age, adverse events reported for Clarinex and placebo in at least 2 percent of subjects receiving Clarinex Oral Solution and at a frequency greater than placebo were
  • upper respiratory tract infections (21.2%, 12.9%),
  • diarrhea (19.7%, 8.1%),
  • fever (12.1%, 1.6%),
  •  irritability (12.1%, 11.3%),
  • coughing (10.6%, 9.7%),
  • somnolence (9.1%, 8.1%),
  • bronchitis (6.1%, 0%),
  • otitis media (6.1%, 1.6%),
  • vomiting (6.1%, 3.2%),
  • anorexia (4.5%, 1.6%),
  •  pharyngitis (4.5%, 1.6%),
  • insomnia (4.5%, 0%),
  • rhinorrhea (4.5%, 3.2%),
  • erythema (3.0%, 1.6%), and
  • nausea (3.0%, 0%).
• There were no clinically meaningful changes in any electrocardiographic parameter, including the QTc interval.
• Only one of the 246 pediatric subjects receiving Clarinex Oral Solution in the clinical trials discontinued treatment because of an adverse event.

Post-Marketing Experience

Because adverse events are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. The following spontaneous adverse events have been reported during the marketing of desloratadine:

• Cardiac disorders: tachycardia, palpitations
• Respiratory, thoracic and mediastinal disorders: dyspnea
• Skin and subcutaneous tissue disorders: rash, pruritus
• Nervous system disorders: psychomotor hyperactivity, movement disorders (including dystonia, tics, and extrapyramidal symptoms), seizures (reported in patients with and without a known seizure disorder)
• Immune system disorders: hypersensitivity reactions (such as urticaria, edema and anaphylaxis)
• Investigations: elevated liver enzymes including bilirubin
• Hepatobiliary disorders: hepatitis
• Metabolism and nutrition disorders: increased appetite

Inhibitors Of Cytochrome P450 3A4

• In controlled clinical studies co-administration of desloratadine with ketoconazole, erythromycin, or azithromycin resulted in increased plasma concentrations of desloratadine and 3 hydroxydesloratadine, but there were no clinically relevant changes in the safety profile of desloratadine.

Fluoxetine

• In controlled clinical studies co-administration of desloratadine with fluoxetine, a selective serotonin reuptake inhibitor (SSRI), resulted in increased plasma concentrations of desloratadine and 3 hydroxydesloratadine, but there were no clinically relevant changes in the safety profile of desloratadine.

Cimetidine

• In controlled clinical studies co-administration of desloratadine with cimetidine, a histamine H2-receptor antagonist, resulted in increased plasma concentrations of desloratadine and 3 hydroxydesloratadine, but there were no clinically relevant changes in the safety profile of desloratadine.

Drug Abuse And Dependence

• There is no information to indicate that abuse or dependency occurs with Clarinex Tablets.