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 felbamate and abarelix. 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 felbamate, when combined with abarelix (100%). We do not expect any change in exposure for abarelix, when combined with felbamate (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.
Felbamate has a high oral bioavailability [ F ] of 90%, which is why the maximum plasma level [Cmax] tends to change little during an interaction. The terminal half-life [ t12 ] is 21.5 hours and constant plasma levels [ Css ] are reached after approximately 86 hours. Protein binding [ Pb ] is not known. About 50.0% of an administered dose is excreted unchanged via the kidneys and this proportion is seldom changed by interactions. The metabolism takes place via CYP2E1 and CYP3A4, among others and the active transport takes place in particular via PGP.
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.
|Serotonergic Effects a||0||Ø||Ø|
Rating: According to our knowledge, neither felbamate nor abarelix increase serotonergic activity.
|Kiesel & Durán b||0||Ø||Ø|
Rating: According to our knowledge, neither felbamate nor abarelix increase anticholinergic activity.
QT time prolongation
Rating: In combination, felbamate and abarelix can potentially trigger ventricular arrhythmias of the torsades de pointes type.
General adverse effects
|Side effects||∑ frequency||fel||aba|
|Loss of appetite||1.0 %||+||n.a.|
|Aplastic anemia||0.0 %||0.01||n.a.|
|Liver failure||0.0 %||0.01||n.a.|
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: AIMS: The purpose of this study was to evaluate the effects of renal impairment on the single-dose pharmacokinetics of the antiepileptic felbamate. METHODS: Twelve subjects with three levels of renal dysfunction (creatinine clearance > 30-80, > 10-30 or 5-10 m min(-1)) and four controls with normal renal function (creatinine clearance > 80 ml min(-1) were studied). Plasma and urine samples were obtained for 144 h following administration of a single 1200 mg dose. RESULTS: Compared with controls, apparent total body clearance, renal clearance and urinary excretion of felbamate were decreased, and half-life, Cmax and AUC values were increased in subjects with renal dysfunction. The magnitude of these changes was associated with the degree of renal dysfunction. Nonrenal clearance and apparent volume of distribution values were also lower in renal dysfunction subjects, but there was no association between the extent of these changes and degree of renal dysfunction. Renal clearance of felbamate accounted for approximately 30% of apparent total body clearance in the control group and from 9-22% in the renal failure patients. Renal clearance of felbamate was significantly correlated with creatinine clearance (r = 0.75; P< 0.001). CONCLUSIONS: These data suggest that initial dosage and titration of felbamate may require adjustment in patients with renal dysfunction.