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 abiraterone and atomoxetine. Please also consult the relevant specialist information.
|Atomoxetine||1.25 [0.45,11.15] 1||1.25|
The reported changes in exposure correspond to the changes in the plasma concentration-time curve [ AUC ]. Atomoxetine exposure increases to 125%, when combined with abiraterone (125%). The AUC is between 45% and 1115% depending on the CYP2D6
The pharmacokinetic parameters of the average population are used as the starting point for calculating the individual changes in exposure due to the interactions.
Abiraterone has a mean oral bioavailability [ F ] of 50%, which is why the maximum plasma levels [Cmax] tend to change with an interaction. The terminal half-life [ t12 ] is 18 hours and constant plasma levels [ Css ] are reached after approximately 72 hours. The protein binding [ Pb ] is very strong at 99.8% and the volume of distribution [ Vd ] is very large at 2815 liters, The metabolism mainly takes place via CYP3A4.
Atomoxetine has a mean oral bioavailability [ F ] of 63%, which is why the maximum plasma levels [Cmax] tend to change with an interaction. The terminal half-life [ t12 ] is rather short at 5.2 hours and constant plasma levels [ Css ] are reached quickly. The protein binding [ Pb ] is 98% strong and the volume of distribution [ Vd ] is 60 liters, Since the substance has a low hepatic extraction rate of 0.28, displacement from protein binding [Pb] in the context of an interaction can lead to increased exposure. The metabolism takes place via CYP2C19 and CYP2D6, among others.
|Serotonergic Effects a||0||Ø||Ø|
Rating: According to our knowledge, neither abiraterone nor atomoxetine increase serotonergic activity.
|Kiesel & Durán b||0||Ø||Ø|
Rating: According to our knowledge, neither abiraterone nor atomoxetine increase anticholinergic activity.
QT time prolongation
Rating: In combination, abiraterone and atomoxetine can potentially trigger ventricular arrhythmias of the torsades de pointes type.
General adverse effects
|Side effects||∑ frequency||abi||ato|
|Peripheral edema||20.0 %||20.0||n.a.|
|Loss of appetite||16.0 %||n.a.||16.0|
|Elevated ALT||13.0 %||13.0||n.a.|
Elevated AST (13%): abiraterone
Liver failure: atomoxetine
Urinary tract infection (10%): abiraterone
Abdominal pain (10%): atomoxetine
Vomiting (10%): atomoxetine
Diarrhea (5.5%): abiraterone
Headache (10%): atomoxetine
Somnolence (10%): atomoxetine
Dizziness (8%): atomoxetine
Fatigue (10%): atomoxetine
Sepsis (5.5%): abiraterone
Dysmenorrhea (3%): atomoxetine
Erectile dysfunction: atomoxetine
Atrial fibrillation (2.6%): abiraterone
Angina pectoris (1.6%): abiraterone
Weight loss (2%): atomoxetine
Mood changes: atomoxetine
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: No Abstract available
Abstract: Atomoxetine (Strattera, a potent and selective inhibitor of the presynaptic norepinephrine transporter, is used clinically for the treatment of attention-deficit hyperactivity disorder (ADHD) in children, adolescents and adults. Atomoxetine has high aqueous solubility and biological membrane permeability that facilitates its rapid and complete absorption after oral administration. Absolute oral bioavailability ranges from 63 to 94%, which is governed by the extent of its first-pass metabolism. Three oxidative metabolic pathways are involved in the systemic clearance of atomoxetine: aromatic ring-hydroxylation, benzylic hydroxylation and N-demethylation. Aromatic ring-hydroxylation results in the formation of the primary oxidative metabolite of atomoxetine, 4-hydroxyatomoxetine, which is subsequently glucuronidated and excreted in urine. The formation of 4-hydroxyatomoxetine is primarily mediated by the polymorphically expressed enzyme cytochrome P450 (CYP) 2D6. This results in two distinct populations of individuals: those exhibiting active metabolic capabilities (CYP2D6 extensive metabolisers) and those exhibiting poor metabolic capabilities (CYP2D6 poor metabolisers) for atomoxetine. The oral bioavailability and clearance of atomoxetine are influenced by the activity of CYP2D6; nonetheless, plasma pharmacokinetic parameters are predictable in extensive and poor metaboliser patients. After single oral dose, atomoxetine reaches maximum plasma concentration within about 1-2 hours of administration. In extensive metabolisers, atomoxetine has a plasma half-life of 5.2 hours, while in poor metabolisers, atomoxetine has a plasma half-life of 21.6 hours. The systemic plasma clearance of atomoxetine is 0.35 and 0.03 L/h/kg in extensive and poor metabolisers, respectively. Correspondingly, the average steady-state plasma concentrations are approximately 10-fold higher in poor metabolisers compared with extensive metabolisers. Upon multiple dosing there is plasma accumulation of atomoxetine in poor metabolisers, but very little accumulation in extensive metabolisers. The volume of distribution is 0.85 L/kg, indicating that atomoxetine is distributed in total body water in both extensive and poor metabolisers. Atomoxetine is highly bound to plasma albumin (approximately 99% bound in plasma). Although steady-state concentrations of atomoxetine in poor metabolisers are higher than those in extensive metabolisers following administration of the same mg/kg/day dosage, the frequency and severity of adverse events are similar regardless of CYP2D6 phenotype.Atomoxetine administration does not inhibit or induce the clearance of other drugs metabolised by CYP enzymes. In extensive metabolisers, potent and selective CYP2D6 inhibitors reduce atomoxetine clearance; however, administration of CYP inhibitors to poor metabolisers has no effect on the steady-state plasma concentrations of atomoxetine.
Abstract: AIM: The effects of atomoxetine (20 and 60 mg twice daily), 400 mg moxifloxacin and placebo on QT(c) in 131 healthy CYP2D6 poor metabolizer males were compared. METHODS: Atomoxetine doses were selected to result in plasma concentrations that approximated expected plasma concentrations at both the maximum recommended dose and at a supratherapeutic dose in CYP2D6 extensive metabolizers. Ten second electrocardiograms were obtained for time-matched baseline on days -2 and -1, three time points after dosing on day 1 for moxifloxacin and five time points on day 7 for atomoxetine and placebo. Maximum mean placebo-subtracted change from baseline model-corrected QT (QT(c)M) on day 7 was the primary endpoint. RESULTS: QT(c)M differences for atomoxetine 20 and 60 mg twice daily were 0.5 ms (upper bound of the one-sided 95% confidence interval 2.2 ms) and 4.2 ms (upper bound of the one-sided 95% confidence interval 6.0 ms), respectively. As plasma concentration of atomoxetine increased, a statistically significant increase in QT(c) was observed. The moxifloxacin difference from placebo met the a priori definition of non-inferiority. Maximum mean placebo-subtracted change from baseline QT(c)M for moxifloxacin was 4.8 ms and this difference was statistically significant. Moxifloxacin plasma concentrations were below the concentrations expected from the literature. However, the slope of the plasma concentration-QT(c) change observed was consistent with the literature. CONCLUSION: Atomoxetine was not associated with a clinically significant change in QT(c). However, a statistically significant increase in QT(c) was associated with increasing plasma concentrations.
Abstract: Three open-label, single-dose studies investigated the impact of hepatic or renal impairment on abiraterone acetate pharmacokinetics and safety/tolerability in non-cancer patients. Patients (n = 8 each group) with mild/moderate hepatic impairment or end-stage renal disease (ESRD), and age-, BMI-matched healthy controls received a single oral 1,000 mg abiraterone acetate (tablet dose); while patients (n = 8 each) with severe hepatic impairment and matched healthy controls received 125- and 2,000-mg abiraterone acetate (suspension doses), respectively (systemic exposure of abiraterone acetate suspension is approximately half to that of tablet formulation). Blood was sampled at specified timepoints up to 72 or 96 hours postdose to measure plasma abiraterone concentrations. Abiraterone exposure was comparable between healthy controls and patients with mild hepatic impairment or ESRD, but increased by 4-fold in patients with moderate hepatic impairment. Despite a 16-fold reduction in dose, abiraterone exposure in patients with severe hepatic impairment was about 22% and 44% of the Cmax and AUC∞ of healthy controls, respectively. These results suggest that abiraterone pharmacokinetics were not changed markedly in patients with ESRD or mild hepatic impairment. However, the capacity to eliminate abiraterone was substantially compromised in patients with moderate or severe hepatic impairment. A single-dose administration of abiraterone acetate was well-tolerated.
Abstract: Atomoxetine is indicated for the treatment of attention deficit hyperactivity disorder and is predominantly metabolized by the CYP2D6 enzyme. Differences in pharmacokinetic parameters as well as clinical treatment outcomes across CYP2D6 genotype groups have resulted in dosing recommendations within the product label, but clinical studies supporting the use of genotype guided dosing are currently lacking. Furthermore, pharmacokinetic and clinical studies have primarily focused on extensive as compared with poor metabolizers, with little information known about other metabolizer categories as well as genes involved in the pharmacodynamics of atomoxetine. This review describes the pharmacogenetic associations with atomoxetine pharmacokinetics, treatment response and tolerability with considerations for the clinical utility of this information.
Abstract: Atomoxetine is a selective norepinephrine (NE) reuptake inhibitor approved for the treatment of attention-deficit/hyperactivity disorder (ADHD) in children (≥6 years of age), adolescents, and adults. Its metabolism and disposition are fairly complex, and primarily governed by cytochrome P450 (CYP) 2D6 (CYP2D6), whose protein expression varies substantially from person to person, and by race and ethnicity because of genetic polymorphism. These differences can be substantial, resulting in 8-10-fold differences in atomoxetine exposure between CYP2D6 poor metabolizers and extensive metabolizers. In this review, we have attempted to revisit and analyze all published clinical pharmacokinetic data on atomoxetine inclusive of public access documents from the new drug application submitted to the United States Food and Drug Administration (FDA). The present review focuses on atomoxetine metabolism, disposition, and genetic polymorphisms of CYP2D6 as they specifically relate to atomoxetine, and provides an in-depth discussion of the fundamental pharmacokinetics of the drug including its absorption, distribution, metabolism, and excretion in pediatric and adult populations. Further, a summary of relationships between genetic variants of CYP2D6 and to some degree, CYP2C19, are provided with respect to atomoxetine plasma concentrations, central nervous system (CNS) pharmacokinetics, and associated clinical implications for pharmacotherapy. Lastly, dosage adjustments based on pharmacokinetic principles are discussed.
Abstract: Two novel oral drugs that target androgen signaling have recently become available for the treatment of metastatic castration-resistant prostate cancer (mCRPC). Abiraterone acetate inhibits the synthesis of the natural ligands of the androgen receptor, whereas enzalutamide directly inhibits the androgen receptor by several mechanisms. Abiraterone acetate and enzalutamide appear to be equally effective for patients with mCRPC pre- and postchemotherapy. Rational decision making for either one of these drugs is therefore potentially driven by individual patient characteristics. In this review, an overview of the pharmacokinetic characteristics is given for both drugs and potential and proven drug-drug interactions are presented. Additionally, the effect of patient-related factors on drug disposition are summarized and the limited data on the exposure-response relationships are described. The most important pharmacological feature of enzalutamide that needs to be recognized is its capacity to induce several key enzymes in drug metabolism. The potency to cause drug-drug interactions needs to be addressed in patients who are treated with multiple drugs simultaneously. Abiraterone has a much smaller drug-drug interaction potential; however, it is poorly absorbed, which is affected by food intake, and a large interpatient variability in drug exposure is observed. Dose reductions of abiraterone or, alternatively, the selection of enzalutamide, should be considered in patients with hepatic dysfunction. Understanding the pharmacological characteristics and challenges of both drugs could facilitate decision making for either one of the drugs.
Abstract: We present a case of a 77 year-old gentleman with previous coronary artery bypass grafting, admitted to hospital with recurrent torsades de pointes (TdP) due to abiraterone-induced hypokalaemia and prolonged QTc. The patient was on abiraterone and prednisone for metastatic prostate cancer. He required multiple defibrillations for recurrent TdP. Abiraterone is a relatively novel drug used in metastatic prostate cancer and we discuss this potential adverse effect and its management in this unusual presentation.
Abstract: BACKGROUND: The effects of atomoxetine on QT in adults remain unclear. In this study, we examined whether the use of atomoxetine to treat attention-deficit hyperactivity disorder in adults is associated with QT prolongation. METHODS: Forty-one subjects with attention-deficit hyperactivity disorder were enrolled in this study. Participants were administered 40, 80, or 120 mg atomoxetine daily and were maintained on their respective dose for at least 2 weeks. We conducted electrocardiographic measurements and blood tests, measuring plasma atomoxetine concentrations after treatment. Electrocardiograms of 24 of the patients were also obtained before atomoxetine treatment. The QT interval was corrected using Bazett (QTcB) and Fridericia (QTcF) correction formulas. RESULTS: In these 24 patients, only the female patients had prolonged QTcB (P = 0.039) after atomoxetine treatment. There was no correlation between plasma atomoxetine concentrations and the corrected QT interval (QTc), or between atomoxetine dosage and the QTc. However, in female patients, there was a significant positive correlation between atomoxetine dosage and the QTcB (r = 0.631, P = 0.012), and there was a marginally significant positive correlation between atomoxetine dosage and the QTcF (r = 0.504, P = 0.055). In male patients, there was no correlation between atomoxetine dosage and the QTcB or QTcF intervals. There was no correlation between plasma atomoxetine concentrations and the QTc in either female or male patients. IMPLICATIONS: Clinicians should exhibit caution when prescribing atomoxetine, particularly for female patients.
Abstract: Physiologically based pharmacokinetic (PBPK) modeling of drug disposition and drug-drug interactions (DDIs) has become a key component of drug development. PBPK modeling has also been considered as an approach to predict drug disposition in special populations. However, whether models developed and validated in healthy populations can be extrapolated to special populations is not well established. The goal of this study was to determine whether a drug-specific PBPK model validated using healthy populations could be used to predict drug disposition in specific populations and in organ impairment patients. A full PBPK model of atomoxetine was developed using a training set of pharmacokinetic (PK) data from CYP2D6 genotyped individuals. The model was validated using drug-specific acceptance criteria and a test set of 14 healthy subject PK studies. Population PBPK models were then challenged by simulating the effects of ethnicity, DDIs, pediatrics, and renal and hepatic impairment on atomoxetine PK. Atomoxetine disposition was successfully predicted in 100% of healthy subject studies, 88% of studies in Asians, 79% of DDI studies, and 100% of pediatric studies. However, the atomoxetine area under the plasma concentration versus time curve (AUC) was overpredicted by 3- to 4-fold in end stage renal disease and hepatic impairment. The results show that validated PBPK models can be extrapolated to different ethnicities, DDIs, and pediatrics but not to renal and hepatic impairment patients, likely due to incomplete understanding of the physiologic changes in these conditions. These results show that systematic modeling efforts can be used to further refine population models to improve the predictive value in this area.