Fexofenadine in dermatology

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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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