43076-30-8Relevant articles and documents
Mechanism of block of a human cardiac potassium channel by terfenadine racemate and enantiomers
Yang,Prakash,Roden,Snyders
, p. 267 - 274 (1995)
1. The cardiac toxicity of racemic terfenadine (marked QT prolongation and polymorphic ventricular arrhythmias) is probably due to potassium channel blockade. To test whether one of its enantiomers would be a less efficient potassium channel blocker, we compared the mechanism of action of the racemate with that of the individual enantiomers. 2. We synthesized the individual enantiomers of terfenadine and examined under whole cell voltage-clamp conditions the mechanism of action of the racemate, both enantiomers and a major metabolite on a cloned human cardiac potassium channel, hKv1.5. This delayed rectifier is sensitive to quinidine, clofilium and other 'class III' antiarrhythmic drugs at clinically relevant concentrations. 3. Upon depolarization, racemic terfenadine and its enantiomers induced a fast decline of hKv1.5 current towards a reduced steady state current level. During subsequent repolarization the tail currents deactivated more slowly than the control, resulting in a 'crossover' phenomenon. 4. The voltage-dependence of block was biphasic with a steep increase in block over the voltage range of channel opening (-30 to 0 mV), and a more shallow phase positive to 0 mV (where the channel is fully open). The latter was consistent with a binding reaction sensing 21% of the transmembrane electrical field (with reference to the cell interior). 5. The EC50 for hKv1.5 block by racemic terfenadine was 0.88 μM, while the values for R- and S-terfenadine were 1.19 μM and 1.16 μM, respectively. In contrast, the acid metabolite reduced hKv1.5 current by only 5% at a concentration of 50 μM. 6. These findings suggest that terfenadine blocks the hKv1.5 channel after it opens by entering into the internal mouth of the channel. We have previously shown that quinidine blocks hKv1.5 in a similar manner but with an apparent affinity of ~6 μM. Thus, terfenadine and its enantiomers are approximately equipotent open state blockers of this human K+ channel and about 6 times more potent than quinidine. The similar state-, time-, and voltage-dependence of hKv1.5 block by both enantiomers also indicates that the chiral centre does not significantly constrain the orientation of critical binding determinants of terfenadine with respect to the receptor site.
METHODS AND COMPOSITIONS FOR TREATING INFECTION
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Paragraph 0205, (2015/09/28)
Provided herein are compositions and methods for treating or preventing infection.
Identification of terfenadine as an inhibitor of human CD81-receptor HCV-E2 interaction: Synthesis and structure optimization
Holzer, Marcel,Ziegler, Sigrid,Albrecht, Beatrice,Kronenberger, Bernd,Kaul, Artur,Bartenschlager, Ralf,Kattner, Lars,Klein, Christian D.,Hartmann, Rolf W.
, p. 1081 - 1110 (2008/09/21)
Terfenadine (4-[4-(hydroxydiphenylmethyl)-1-piperidyl]-1-(4-tert- butylphenyl)-butan-1-ol) was identified in a biological screening to be a moderate inhibitor (27 % inhibition) of the CD81-LEL-HCV-E2 interaction. To increase the observed biological activity, 63 terfenadine derivates were synthesized via microwave assisted nucleophilic substitution. The prepared compounds were tested for their inhibitory potency by means of a fluorescence labeled antibody assay using HUH7.5 cells. Distinct structure-activity relationships could be derived. Optimization was successful, leading to 3g, identfied as the most potent compound (69 % inhibition). Experiments with viral particles revealed that there might be additional HCV infection reducing mechanisms.
