QT time prolongation
Adverse drug events
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Explanations of the substances for patients
We have no additional warnings for the combination of abarelix and ibutilide. Please also consult the relevant specialist information.
The reported changes in exposure correspond to the changes in the plasma concentration-time curve [ AUC ]. We do not expect any change in exposure for abarelix, when combined with ibutilide (100%). We do not expect any change in exposure for ibutilide, when combined with abarelix (100%).
The pharmacokinetic parameters of the average population are used as the starting point for calculating the individual changes in exposure due to the interactions.
The bioavailability of abarelix is unknown. The terminal half-life [ t12 ] is rather long at 316.8 hours and constant plasma levels [ Css ] are only reached after more than 1267.2 hours. The protein binding [ Pb ] is 97.5% strong. The metabolism via cytochromes is currently still being worked on.
The bioavailability of ibutilide is unknown. The terminal half-life [ t12 ] is rather short at 6 hours and constant plasma levels [ Css ] are reached quickly. The protein binding [ Pb ] is rather weak at 40%. The metabolism does not take place via the common cytochromes.
|Serotonergic Effects a||0||Ø||Ø|
Rating: According to our knowledge, neither abarelix nor ibutilide increase serotonergic activity.
|Kiesel & Durán b||0||Ø||Ø|
Rating: According to our knowledge, neither abarelix nor ibutilide increase anticholinergic activity.
QT time prolongation
Rating: In combination, abarelix and ibutilide can potentially trigger ventricular arrhythmias of the torsades de pointes type.
General adverse effects
|Side effects||∑ frequency||aba||ibu|
|Ventricular arrhythmia||2.6 %||n.a.||2.6|
|Cerebrovascular accident||0.0 %||n.a.||0.01|
|Renal failure||0.0 %||n.a.||0.01|
|Pulmonary edema||0.0 %||n.a.||0.01|
Based on your answers and scientific information, we assess the individual risk of undesirable side effects. These recommendations are intended to advise professionals and are not a substitute for consultation with a doctor. In the restricted test version (alpha), the risk of all substances has not yet been conclusively assessed.
Abstract: BACKGROUND: Clinical and experimental in vitro observations indicate that female gender is associated with a higher risk of developing torsades de pointes with repolarizing-delaying agents. The present study addressed the question of gender difference in the susceptibility towards developing torsades de pointes in a rabbit model of the acquired long QT syndrome in vivo. METHODS AND RESULTS: Female (F, n = 40) or male (M, n = 40) NZW rabbits, characterized as young (Y, n = 20) or adult (A, n = 20) were anesthetized with alpha-chloralose and sensitized to developing torsades de pointes by a continuous infusion of methoxamine. The class III antiarrhythmic agent ibutilide was subsequently infused at a rate of 8 nmol/kg/min for 30 minutes maximum. Before commencement of drug infusion, no gender-related differences in the QT interval were observed (121 +/- 1.9 msec and 126 +/- 3.3 msec in FA and in MA and 116 +/- 1.6 msec and 113 +/- 1.7 msec in the FY and MY, respectively). Infusion of ibutilide was associated with a rapid and marked increase in the QT interval, which did not differ significantly between the groups. Hence, the maximal QT lengthening observed was 39 +/- 3.1% in FA, 46 +/- 5.7% in MA, 38 +/- 3.9% in FY and 36 +/- 3.4% in MY, respectively (p > 0.05 between gender). In the adults, the incidence of torsades de pointes in F was 70% and in M 90% (p = 0.235), whereas in the young, the incidence in F was 45% and in M 70% (p = 0.200). The cumulative doses of ibutilide causing torsades de pointes were not statistically significantly different between the four groups of rabbits (70 +/- 15.5 nmol/kg in FA, 50 +/- 5.3 nmol/kg in MA, 59 +/- 17.2 nmol/kg in FY and 61 +/- 15.9 nmol/kg in MY, respectively). CONCLUSIONS: In this in vivo rabbit model of the acquired long QT syndrome, female gender was not associated with a longer repolarization time (QT interval), an excessive change in the baseline QT interval or a higher incidence of torsades de pointes in response to ibutilide challenge.
Abstract: Ibutilide is a class III antiarrhythmic agent used for the termination of atrial fibrillation and atrial flutter. It mainly affects membrane potassium currents and prolongs the cardiac action potential. This effect is reflected as QT interval prolongation on the surface electrocardiogram. Like other drugs that affect potassium currents, ibutilide is prone to induce a malignant ventricular tachycardia, torsade de pointes. We report four cases of torsade de pointes after administration of ibutilide for pharmacologic cardioversion of atrial fibrillation and atrial flutter; three of these cases required direct current cardioversion for termination of torsade de pointes. All four patients were female. We discuss the risk factors for development of ibutilide-induced torsade de pointes.