Can cetirizine and chlorpheniramine maleate be prescribed together?

Cetirizine and Chlorpheniramine Combination Therapy

Yes, cetirizine and chlorpheniramine maleate can be prescribed together, with the common practice being to use cetirizine (non-sedating) during the day and chlorpheniramine (sedating) at night to improve sleep in patients with urticaria or allergic conditions. 1

Rationale for Combination Therapy

• The British Journal of Dermatology guidelines specifically mention that adding a sedating antihistamine at night (such as chlorpheniramine 4-12 mg) to a non-sedating antihistamine (like cetirizine) taken during the day can help patients sleep better 1
• This combination leverages the complementary properties of both medications:
  • Cetirizine: Second-generation, less sedating, once-daily dosing, effective for 24-hour symptom control 2
  • Chlorpheniramine: First-generation, sedating properties beneficial at night, helps with sleep disruption from allergic symptoms 1, 3

Clinical Considerations

Efficacy

• Cetirizine demonstrates effective 24-hour relief of allergic symptoms regardless of dosing regimen 4
• Cetirizine has shown superior antiallergic activity compared to chlorpheniramine in studies of chronic idiopathic urticaria 5
• The combination may provide better symptom control, particularly for overnight and early morning symptoms 4

Safety Concerns

1. Sedation risk:

   • Chlorpheniramine has significant sedative effects that can lead to cognitive impairment 6
   • Only 2.8% of patients on cetirizine experience drowsiness compared to 54.2% on chlorpheniramine 5
   • The intentional use of chlorpheniramine's sedating properties at night can be beneficial for sleep but patients should be warned about morning drowsiness

2. Special populations:

   • Liver disease: Both medications should be used with caution in severe liver disease; chlorpheniramine should be avoided as its sedating effect is inappropriate 1
   • Renal impairment: Cetirizine dose should be halved in moderate renal impairment 1
   • Elderly: Higher risk of cognitive decline, falls, and anticholinergic effects with chlorpheniramine 6
   • Pregnancy: Both should be avoided if possible, especially in first trimester 1

Practical Prescribing Approach

1. Standard dosing regimen:

   • Cetirizine 10 mg once daily in the morning
   • Chlorpheniramine 4-12 mg at bedtime

2. Monitoring:

   • Assess for excessive daytime drowsiness
   • Monitor for anticholinergic side effects (dry mouth, urinary retention, constipation)
   • Evaluate efficacy of symptom control throughout the 24-hour period

3. Cautions:

   • Advise patients about potential driving impairment, especially in the morning
   • If planning allergy testing, cetirizine should be discontinued appropriately before testing 6

Alternative Approaches

• If the combination causes excessive sedation, consider using cetirizine alone at a higher dose (off-label) 1
• For patients with liver disease, consider using second-generation antihistamines at reduced doses 6
• Addition of an H2 antihistamine may sometimes provide better control of urticaria than an H1 antihistamine alone 1

While this combination is commonly used in clinical practice, the prescriber should carefully consider the individual patient's circumstances, particularly regarding sedation risk, comorbidities, and potential drug interactions.