What is the recommended dosage and treatment plan for Allegra M (fexofenadine and montelukast) in managing allergy symptoms and asthma?

Allegra M (Fexofenadine + Montelukast) Dosing and Treatment Plan

For managing allergic rhinitis with or without asthma, administer fexofenadine 120-180 mg once daily (or 60 mg twice daily) combined with montelukast 10 mg once daily in the evening. 1, 2

Specific Dosing Recommendations

Fexofenadine Component

• Adults and children ≥12 years: 60 mg twice daily OR 180 mg once daily with water 1
• Children 6-11 years: 30 mg twice daily with water 1
• Renal impairment: Start with 60 mg once daily (adults) or 30 mg once daily (children 6-11 years) 1
• Onset of action: Relief begins within ≤2 hours 3

Montelukast Component

• Adults and children ≥12 years: 10 mg once daily, preferably in the evening 2, 4
• Children 6-11 years: 5 mg once daily 4
• Children 1-5 years: 4 mg once daily 4
• Onset of action: Clinical benefits begin within 1-2 days 2

Treatment Algorithm by Condition Severity

For Allergic Rhinitis Alone

• Mild intermittent symptoms: Fexofenadine monotherapy may suffice 3, 5
• Moderate-to-severe or persistent symptoms: Combination therapy with fexofenadine + montelukast provides additive benefit 4, 2
• Important caveat: This combination is less effective than intranasal corticosteroids but serves as an alternative for patients unable or unwilling to use nasal steroids 4, 5

For Allergic Rhinitis with Concurrent Asthma

• Mild persistent asthma: Montelukast 10 mg daily can serve dual purpose for both conditions 4
• Step 2 asthma care: Montelukast is an alternative (not preferred) to low-dose inhaled corticosteroids 4
• Step 3 or higher asthma: Montelukast should be added to inhaled corticosteroids, not used as monotherapy 4
• Critical safety point: Approximately 40% of allergic rhinitis patients have coexisting asthma, making this combination particularly rational 4

Administration Guidelines

Timing and Coordination

• No timing restrictions: Both medications can be taken concurrently without drug interactions 2
• Optimal timing: Montelukast preferably in evening based on pharmacodynamics; fexofenadine can be taken morning or evening 2
• Food considerations: Fexofenadine should be taken with water; avoid fruit juices which may reduce absorption 1

Duration of Therapy

• Continuous daily use: Both medications provide preventive control rather than acute symptom relief 2, 5
• Seasonal allergic rhinitis: Use throughout pollen season 3
• Perennial allergic rhinitis: Ongoing daily therapy as needed 1, 5

Critical Safety Monitoring

FDA Black Box Warning for Montelukast

• Monitor for neuropsychiatric events: Depression, mood changes, suicidal thoughts, and unusual behavioral changes 2
• Patient counseling required: Inform patients and caregivers to report any mood or behavioral changes immediately 2

Fexofenadine Safety Profile

• Cardiac safety: No QT prolongation or cardiac toxicity, even with doses up to 240 mg/day 3, 6
• Non-sedating: Does not cross blood-brain barrier; no cognitive or psychomotor impairment 3, 6
• Adverse events: Headache most common, but incidence similar to placebo 3, 6

Dose Adjustments Required

• Renal impairment: Reduce fexofenadine to 60 mg once daily (adults) or 30 mg once daily (children) 1, 2
• Hepatic impairment: No specific adjustments listed for fexofenadine; montelukast requires no adjustment 2
• Normal organ function: No dose adjustments needed when using combination therapy 2

Common Pitfalls to Avoid

Inappropriate Monotherapy

• Never use montelukast alone for moderate-to-severe asthma: Must be combined with inhaled corticosteroids at Step 3 or higher 4
• Recognize limitations: Montelukast is less effective than inhaled corticosteroids for both rhinitis and asthma 4, 5

Unrealistic Expectations

• Symptom profile: Fexofenadine effectively treats sneezing, rhinorrhea, itching, and eye symptoms but has modest effects on nasal congestion 3
• Consider adding decongestant: If nasal congestion predominates, pseudoephedrine may be needed in addition 3, 7

Quality of Life Considerations

• Fexofenadine improves QOL: Produces clinically meaningful improvements compared to loratadine 3
• Compliance advantage: Once-daily dosing for both medications enhances adherence 4, 5
• Steroid-phobic families: This combination particularly useful when treating children whose parents refuse corticosteroids 4