| Item |
Information |
|
Drug Groups
|
approved; withdrawn |
|
Description
|
In the U.S., Terfenadine was superseded by fexofenadine in the 1990s due to the risk of cardiac arrhythmia caused by QT interval prolongation. |
| Indication |
For the treatment of allergic rhinitis, hay fever, and allergic skin disorders. |
| Pharmacology |
Terfenadine, an H1-receptor antagonist antihistamine, is similar in structure to astemizole and haloperidol, a butyrophenone antipsychotic. The active metabolite of terfenadine is fexofenadine. |
| Toxicity |
Mild (e.g., headache, nausea, confusion), but adverse cardiac events including cardiac arrest, ventricular arrhythmias including torsades de pointes and QT prolongation have been reported. LD50=mg/kg (orally in mice) |
| Affected Organisms |
| • |
Humans and other mammals |
|
| Biotransformation |
Hepatic |
| Absorption |
On the basis of a mass balance study using 14C labeled terfenadine the oral absorption of terfenadine was estimated to be at least 70% |
| Half Life |
3.5 hours |
| Protein Binding |
70% |
| External Links |
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