Indications of fexofenadine in dermatology
- Chronic urticaria: 180 mg daily in adults.
- Mastocytosis: 360 mg in the morning + up to 40 mg of cetirizine at night in adults.
Mechanism of action
- Fexofenadine is the active metabolite of terfenadine.
- It is a selective H1 receptor inverse agonist.
- Fexofenadine has low sedative and anticholinergic effects.
Side effects
- COMMON: headache, dizziness, drowsiness.
- RARE: hypersensitivity reaction, back pain, upper respiratory infection, dyspepsia, fatigue, cough, fever, otitis, sinusitis.
Contraindications
- Hypersensitivity to drug/class.
- Impaired renal function.
- Pregnancy.
Interactions
- Decreased levels of fexofenadine: antacids.
- Increased levels of fexofenadine: ketoconazole, erythromycin.
Pregnancy &Lactation
- Pregnancy category C.
- Lactation: Because of its lack of sedation and low milk levels, maternal use of fexofenadine would not be expected to cause any adverse effects in breastfed infants.
- Fexofenadine might have a negative effect on lactation, especially in combination with a sympathomimetic agent such as pseudoephedrine.
Precautions
- Grapefruit juice can significantly reduce the plasma concentration of fexofenadine.
- It is advised that elderly patients use caution when using fexofenadine, particularly when there is concern for renal impairment.
Drug Info
- Fexofenadine is a second-generation nonsedating antihistamine
- It has the widest therapeutic window of the second‐generation antihistamines, it is least likely to cause sedation.
- Fexofenadine is not metabolized by the liver and is excreted essentially unchanged.
- There is no need for dosage adjustment in the elderly or in patients with mild renal or hepatic impairment.
- No evidence for cardiotoxicity has been detected with fexofenadine.
- Taking erythromycin or ketoconazole while taking fexofenadine does increase the plasma levels of fexofenadine, but this increase does not influence the QT interval.
- Fexofenadine should not to be taken with apple, orange, or grapefruit juice because it could decrease absorption of the drug.
- Fexofenadine should be taken with water.
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