Terfenadine

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Terfenadine
Systematic (IUPAC) name
4-[4-(hydroxy-diphenyl-methyl)-1-piperidyl]- 1-(4-tert-butylphenyl)-butan-1-ol
Identifiers
CAS number	50679-08-8
ATC code	R06 AX12
PubChem	5405
DrugBank	APRD00606
Chemical data
Formula	C₃₂H₄₁N O₂
Mol. weight	471.673 g/mol
Pharmacokinetic data
Bioavailability	?
Protein binding	70%
Metabolism	?
Half life	3.5 hours
Excretion	?
Therapeutic considerations
Pregnancy cat.	?
Legal status
Routes	?

Terfenadine is an antihistamine formerly used for the treatment of allergic conditions. It was marketed under various the brand names including Seldane in the United States, Triludan in the United Kingdom, and Teldane in Australia. It was superseded by fexofenadine in the 1990s due to the risk of cardiac arrhythmia caused by QT interval prolongation.

Terfenadine is a prodrug, generally completely metabolised to the active form fexofenadine by intestinal CYP3A4. Terfenadine itself, however, has a cardiotoxic effect and may be absorbed and reach myocytes if the patient is concurrently taking a CYP3A4 inhibitor (e.g. erythromycin, grapefruit juice).

Antihistamines (primarily R06) edit
Aminoalkyl ethers:	Bromazine, Carbinoxamine, Clemastine, Chlorphenoxamine, Diphenylpyraline, Diphenhydramine, Doxylamine
Substituted alkylamines:	Brompheniramine, Chlorphenamine, Dexbrompheniramine , Dexchlorpheniramine, Dimetindene, Pheniramine, Talastine
Substituted ethylene diamines:	Chloropyramine, Histapyrrodine, Mepyramine, Methapyrilene
Phenothiazine derivatives:	Alimemazine, Hydroxyethylpromethazine, Isothipendyl, Mequitazine, Methdilazine, Oxomemazine, Promethazine
Piperazine derivatives:	Buclizine, Cetirizine, Chlorcyclizine, Cinnarizine, Cyclizine, Hydroxyzine, Levocetirizine, Meclozine, Oxatomide
Others for systemic use:	Acrivastine, Antazoline, Astemizole, Azatadine , Azelastine, Bamipine, Cyproheptadine, Deptropine, Desloratadine, Ebastine, Epinastine, Ketotifen, Loratadine, Mebhydrolin, Mizolastine, Phenindamine, Pimethixene, Pyrrobutamine, Rupatadine, Terfenadine, Triprolidine
For topical use:	Bamipine, Chloropyramine, Chlorphenoxamine, Clemastine, Dimetindene, Diphenhydramine, Isothipendyl, Mepyramine , Promethazine, Thenalidine
Antiallergic agents excluding corticosteroids:	Antazoline, Azelastine , Fexofenadine
Other antiallergics:	Emedastine, Epinastine, Ketotifen, Olopatadine