Recently, there has been considerable attention focused on drugs that prolong the QT interval of the electrocardiogram, with the H(1)-receptor antagonist class of drugs figuring prominently. Albeit rare, incidences of QT prolongation and ventricular arrhythmias, in particular torsade de pointes, have been reported with the antihistamines astemizole and terfenadine and more recently with loratad...

It has been reported that some of H1 receptor antagonists have important effects on cardiovascular system. Terfenadine as a non-sedative H1 receptor antagonist has an arrhythmogenic activity. In this study we have shown the effects of four antihistamine drugs: terfenadine, loratadine, clemastine and diphenhydramine, on the rate and contractions of isolated rat atria. Terfenadine (1-10 µM) cause...

Neurokinin A (NKA) elicits a potent contractile effect in asthmatic airways. Its mechanism of action in bronchial asthma is still unknown. Recent work supports the view that NKA may stimulate mediator release from mast cells. To investigate the relative contribution of mast cell degranulation to the action of NKA, a randomized, double-blind study has been undertaken, to evaluate the effect of a...

Staphylococcus aureus is a rapidly growing health threat in the U.S., with resistance to several commonly prescribed treatments. A high-throughput screen identified the antihistamine terfenadine to possess, previously unreported, antimicrobial activity against S. aureus and other Gram-positive bacteria. In an effort to repurpose this drug, structure-activity relationship studies yielded 84 terf...

The heightened safety concern was precipitated by repeated reports on torsade de pointes (TdP) and other arrhythmias occurring in patients treated with an antihistamine drug (terfenadine) [1]. ECG measurements performed during the clinical development process by cardiologists (allegedly using "eyeball/calliper" techniques), have failed to identify drug-related QT prolongation. The false-negativ...

since the introduction of our local manufacturing of terfenadine, we have observed and expressed our concern about a small but increasing number of serious ventricular arrhythmias associated with the use of this non sedating antihistamine. in january 1997 a case of torsade de pointes ventricular tachycardia was detected in a previously healthy woman taking terfenadine with erythromycin. electro...

It has been proposed that exercise provokes bronchoconstriction in asthma by inducing mast cell degranulation, and that this occurs secondary to the hyperpnoea of exercise causing hypertonicity of the airway lining fluid. We investigated the contribution of the mast cell products, histamine and prostaglandins, to the bronchoconstriction induced by isocapnic hyperventilation (ISH) using single d...

STUDY OBJECTIVE The duration of action of several new non-sedative antihistamine preparations as assessed by skin and bronchial reactivity to histamine has still not been well established. The aim of the study was to evaluate the duration of effect of loratadine (10 mg) and terfenadine (120 mg) administered once a day for one week on cutaneous and inhaled reactivity to histamine by comparison w...

Terfenadine reacts with mixed anhydrides (malonic and acetic anhydrides) producing a yellow-coloured product with intense fluorescence. Based on this fact, a spectrophotometric method was developed for the determination of terfenadine in dosage forms. The relation between the absorbance at 395 nm and the concentration is rectilinear over the range 0.5-5 microg ml(-1) (molar absorptivity is 1.40...