Fexofenadine (Telfast®)

Fexofenadine is a third-generation antihistamine and the active metabolite of terfenadine. It is used for the symptomatic treatment of seasonal allergic rhinitis (hay fever) and chronic idiopathic urticaria.

Fexofenadine is available under the brand name Telfast® and as a generic. It is characterized by particularly low sedation. Fexofenadine practically does not cross the blood-brain barrier.

In studies, fexofenadine showed no changes in the QT interval compared with placebo.

Fexofenadine selectively blocks peripheral H1 receptors:

Mechanism of action:

• Selective blockade of H1 histamine receptors
• Inhibits histamine-mediated vasodilation and edema formation
• Reduces itching, sneezing, and runny nose
• Additional anti-allergic properties (inhibits leukotriene release)

Special features:

• Practically does not cross the blood-brain barrier (substrate of P-glycoprotein)
• No relevant metabolism via CYP enzymes
• No QT prolongation
• No anticholinergic effects

Onset of action: Rapid onset of action within 1 hour. Maximum effect after 2–3 hours. Duration of action 24 hours.

Fexofenadine is suitable for:

• Adults and adolescents aged 12 years and older with seasonal allergic rhinitis
• Patients aged 12 years and older with chronic idiopathic urticaria
• People who depend on being fit to drive (professional drivers, pilots)

Especially recommended for:

• Working people who need to remain fully able to perform
• When other antihistamines cause tiredness

Not suitable:

• Children under 12 years (120/180 mg tablets)
• Hypersensitivity to fexofenadine

Seasonal allergic rhinitis:

• 120 mg once daily

Chronic urticaria:

• 180 mg once daily

Available strengths:

• 120 mg film-coated tablets (hay fever)
• 180 mg film-coated tablets (urticaria)

Dose adjustment:

• No dose adjustment in impaired kidney function
• No dose adjustment in mild to moderate liver impairment

Duration of use:

• Seasonal: during the pollen season
• For urticaria: until symptoms subside, as recommended by a doctor

How to take:

• Take once daily before a meal
• Swallow with water (no grapefruit juice!)
• Always at the same time of day

Important notes:

• Do NOT take with grapefruit, orange, or apple juice (reduced absorption)
• Take antacids (aluminum/magnesium) 2 hours apart
• If you miss a dose: take the next dose at the usual time, do not make up for the missed dose

Tips:

• Ideally take with a glass of tap water
• Fruit juices can reduce absorption by up to 36%
• Take regularly for optimal protection during the pollen season

Fexofenadine must not be taken in case of:

• Hypersensitivity to fexofenadine or any of the other ingredients

Caution in case of:

• Impaired kidney function
• Impaired liver function
• Elderly patients (increased exposure possible)
• A history of cardiovascular disease

Pregnancy and breastfeeding: Should only be taken during pregnancy if there is a compelling indication. Animal studies showed no teratogenicity. Whether fexofenadine passes into breast milk has not been fully clarified. Caution during breastfeeding.

Common (1–10%):

• Headache
• Drowsiness
• Nausea
• Dizziness

Uncommon (0.1–1%):

• Dry mouth
• Tiredness
• Sleep disorders
• Gastrointestinal complaints

Rare:

• Hypersensitivity reactions (skin rash, angioedema)
• Tachycardia
• Diarrhea

Safety profile: In driving simulator studies and in pilots, no impairment of performance was found, even at double the dose.

Increased fexofenadine levels due to:

• Erythromycin (antibiotic)
• Ketoconazole (antifungal)
• Verapamil (calcium channel blocker)

→ However, these combinations are clinically safe (no QT prolongation)

Reduced absorption due to:

• Grapefruit juice, orange juice, apple juice (inhibit OATP transporters)
• Antacids containing aluminum hydroxide/magnesium hydroxide

No relevant interaction with:

• Alcohol (no enhancement of sedation)
• CYP enzyme-dependent medications

Important: Take fexofenadine with water, not with fruit juices. Take antacids at least 2 hours apart.