Terfenadine

Terfenadine

Clinical data
Trade names	Seldane, Triludan, Teldane
AHFS/Drugs.com	Multum Consumer Information
MedlinePlus	a600034
Pregnancy category	US: C (Risk not ruled out)
ATC code	R06AX12 (WHO)
Legal status
Legal status	Withdrawn
Pharmacokinetic data
Protein binding	70%
Biological half-life	3.5 hours
Identifiers
IUPAC name (RS)-1-(4-tert-butylphenyl)-4-{4-[hydroxy(diphenyl)methyl]piperidin-1-yl}-butan-1-ol
CAS Number	50679-08-8 Y
PubChem CID	5405
IUPHAR/BPS	2608
DrugBank	DB00342 Y
ChemSpider	5212 Y
UNII	7BA5G9Y06Q
KEGG	D00521 Y
ChEMBL	CHEMBL17157 Y
ECHA InfoCard	100.051.537
Chemical and physical data
Formula	C32H41NO2
Molar mass	471.673 g/mol
3D model (Jmol)	Interactive image
Chirality	Racemic mixture
SMILES OC(c1ccccc1)(c2ccccc2)C4CCN(CCCC(O)c3ccc(cc3)C(C)(C)C)CC4
InChI InChI=1S/C32H41NO2/c1-31(2,3)26-18-16-25(17-19-26)30(34)15-10-22-33-23-20-29 (21-24-33)32(35,27-11-6-4-7-12-27)28-13-8-5-9-14-28/ h4-9,11-14,16-19,29-30,34-35H,10,15,20-24H2,1-3H3 N Key:GUGOEEXESWIERI-UHFFFAOYSA-N Y
NY (what is this?)

Terfenadine is an antihistamine formerly used for the treatment of allergic conditions. It was brought to market by Hoechst Marion Roussel (now Sanofi-Aventis) and was marketed under various 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 It was superseded by fexofenadine in the 1990s due to the risk of a particular type of disruption of the electrical rhythms of the heart (specifically cardiac arrhythmia caused by QT interval prolongation) and has been withdrawn from markets worldwide.

Terfenadine is a prodrug, generally completely metabolized to the active form fexofenadine in the liver by the enzyme . Due to its near complete metabolism by the liver immediately after leaving the gut, terfenadine normally is not measurable in the plasma. Terfenadine itself, however, is cardiotoxic at higher doses, while its major active metabolite is not. Terfenadine, in addition to its antihistamine effects, also acts as a potassium channel blocker (Kv11.1 encoded by the gene hERG). Since its active metabolite is not a potassium channel blocker, no cardiotoxicity is associated with fexofenadine. Toxicity is possible after years of continued use with no previous problems as a result of an interaction with other medications such as erythromycin, or foods such as grapefruit. The addition of, or a dosage increase in, these CYP3A4 inhibitors makes it harder for the body to metabolize and remove terfenadine. In larger plasma concentrations, it may lead to toxic effects on the heart's rhythm (e.g. ventricular tachycardia and torsades de pointes).