Terfenadine is an antihistamine. Antihistamines prevent sneezing, runny nose, itching and watering of the eyes, and other allergic symptoms. This is used to treat allergies, hives (urticaria), and other allergic inflammatory conditions. Terfenadine may also be used for purposes other than those listed in this medication guide.

Pharmacology

Terfenadine competes with histamine for binding at H1-receptor sites in the GI tract, uterus, large blood vessels, and bronchial muscle. This reversible binding of terfenadine to H1-receptors suppresses the formation of edema, flare, and pruritus resulting from histaminic activity. As the drug does not readily cross the blood-brain barrier, CNS depression is minimal.

Terfenadine is indicated for the treatment of allergic rhinitis, hay fever, and allergic skin disorders.

Adult (>12 year and >50 kg): 60-120 mg in the morning or 60 mg bid. Max: 120 mg daily.

Renal Impairment: CrCl <40: Half the usual daily dose

Porphyria.

Anxiety, palpitations, insomnia, mild GI distubances, erythema multiforme and galactorrhoea.

Child and elderly. Avoid in patients with cardiac or significant hepatic disease, electrolyte imbalance, or known or suspected prolongation of the QT interval. Lactation, pregnancy.

Pregnancy & Lactation

Pregnancy Category C. Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.