- USES: Montelukast is indicated for the prophylaxis and chronic treatment of asthma and acute prevention of exercise-induced bronchoconstriction. It is also indicated for the relief of symptoms of seasonal or perennial allergic rhinitis. PHARMACOLOGY: Montelukast sodium is a selective and active leukotriene (LTD4, LTE4) receptor antagonist. It binds to cysteinyl leukotrienes (CysLT) type-1 receptors found in the human airway (smooth muscle cells and macrophages), which prevents airway edema, smooth muscle contraction and other respiratory inflammation. The leukotrienes are also released from the nasal mucosa after allergen exposure where montelukast sodium may inhibit symptoms of allergic rhinitis. EPIDEMIOLOGY: Exposure is common but significant toxicity is rare. TOXICITY: No clinical effects have been reported in the majority of overdose reports. The most common effects following pediatric overdose include thirst, somnolence, mydriasis, hyperkinesia, and abdominal pain. In postmarketing experience and clinical studies, abdominal pain, somnolence, thirst, headache, vomiting, and psychomotor hyperactivity were reported in adults and children after ingesting montelukast doses as high as 1000 mg. ADVERSE EFFECTS: Adverse effects associated with therapeutic montelukast use include fatigue, maculopapular rash, fever, dyspepsia, gastroenteritis, headache, nasal congestion, upper respiratory infection, cough, eosinophilia, elevated liver enzymes, palpitations, vomiting, pancreatitis, paresthesia, hypoesthesia, insomnia, tremor, drowsiness, abnormal dreams, seizures, agitation, suicidal thinking and behavior, and hallucinations. Montelukast and the other leukotriene antagonists have rarely been associated with the development of Churg-Strauss syndrome, a potentially fatal eosinophilic vasculitis, during therapeutic use. This occurred in adult asthma patients, in most of whom concomitant oral steroid doses were reduced. Effects have included worsening pulmonary symptoms, eosinophilia, vasculitic rash, cardiac complications, and neuropathy.
Range of Toxicity:
- TOXICITY: Overdose information is limited. It is not expected to produce severe toxicity in adults. In postmarketing experience and clinical studies, most adults and children did not experience any toxicity following montelukast doses as high as 1000 mg. The most common reported adverse effects were abdominal pain, somnolence, thirst, headache, vomiting, and psychomotor hyperactivity. In a large pediatric case series, montelukast ingestions of up to 536 mg resulted in minimal or no adverse events. THERAPEUTIC DOSE: ADULTS AND ADOLESCENTS (15 years or older): 10 mg once daily. PEDIATRIC: 6 to 14 years: 5 mg once daily; 2 to 5 years: 4-mg chewable tablet or 1 packet of 4-mg oral granules; 6 to 23 months: 1 packet of 4-mg oral granules.
- Support: MANAGEMENT OF MILD TO MODERATE TOXICITY: Treatment is symptomatic and supportive. MANAGEMENT OF SEVERE TOXICITY: Treatment is symptomatic and supportive. Treat seizures with IV benzodiazepines; barbiturates or propofol may be needed if seizures persist or recur.
- Decontamination: PREHOSPITAL: Serious toxicity is not expected after ingestion of montelukast alone, and prehospital gastrointestinal decontamination is not routinely required. HOSPITAL: Significant toxicity is not expected after overdose; gastrointestinal decontamination is generally not necessary. Activated charcoal should be considered after extremely large ingestions or if more toxic coingestants are involved.
- Antidote: None.
- Airway management: Endotracheal intubation and mechanical ventilation may be required in patients with severe allergic reactions, but this is rare.
- Acute allergic reaction: MILD/MODERATE: Monitor airway. Administer antihistamines with or without inhaled beta agonists, corticosteroids or epinephrine. SEVERE: Oxygen, aggressive airway management, antihistamines, epinephrine, corticosteroids, ECG monitoring and IV fluids.
- Monitoring of patient: Serum montelukast levels are not readily available and are not clinically useful. Monitor vital signs and liver enzymes in all symptomatic patients. Monitor fluid and electrolyte levels in patients with severe vomiting. In rare cases, systemic eosinophilia has been reported, sometimes presenting with the clinical features of Churg-Strauss syndrome. Monitor CBC in patients with worsening of pulmonary symptoms, vasculitic rash, or cardiac complications while receiving montelukast therapy.
- Enhanced elimination procedure: Hemodialysis and hemoperfusion are UNLIKELY to be of value because of the high degree of protein binding and large volume of distribution.
- Patient disposition: HOME CRITERIA: Patients with a minor unintentional exposure who are asymptomatic or have mild symptoms can likely be managed at home. In studies, pediatric ingestions of up to 536 mg (33.71 mg/kg) did not produce any serious adverse events. OBSERVATION CRITERIA: Patients with inadvertent overdoses who have more than mild symptoms and patients with deliberate self harm ingestions should be sent to a health care facility for evaluation and treated until symptoms resolve. ADMISSION CRITERIA: Patients who remain symptomatic despite adequate treatment should be admitted. CONSULT CRITERIA: Consult a Poison Center for assistance in managing patients with severe toxicity or in whom the diagnosis is unclear.