CYTOCHROME P450 3A4 IS THE MAJOR ENZYME INVOLVED IN THE METABOLISM OF THE SUBSTANCE P RECEPTOR ANTAGONIST APREPITANT

Analysis of Nausea and Vomiting Frequency Following Opioid Dose Escalation and Its Risk Factors: A Single-Center Retrospective Observational Study

Background and Objective: Opioid-induced nausea and vomiting (OINV) is known to develop not only upon opioid introduction but also during opioid dose escalation, but the actual details are unclear. The aim of this study was to investigate the frequency of OINV in opioid dose escalation at a single center and to identify risk factors. Methods: A retrospective analysis of the medical records of hospitalized patients with cancer who underwent increased intake of oral oxycodone extended-release tablets at Komaki City Hospital between January 2016 and December 2019 was performed. Associations between the incidence of OINV and multiple factors were analyzed, including patient demographics, opioid daily dose, comorbidities, history of nausea after opioid introduction, and prophylactic antiemetic drugs. Results: Of the 132 patients analyzed, 56 (42.4%; grades 1 and 2, 36 and 20, respectively) developed opioid-induced nausea after opioid dose escalation, 26 (19.7%; grades 1 and 2, 19 and 7, respectively) developed opioid-induced vomiting, 58 (43.9%) had either opioid-induced nausea or vomiting. Thirty-five of 60 patients (55.0%) developed OINV among those who received prophylactic antiemetic drugs at opioid dose escalation. Performance status (≥2) (odds ratio [OR]: 2.36, 95% confidence interval [95% CI]: 1.15-4.84, p = 0.02) and history of nausea for opioid introduction (OR: 2.92, 95% CI: 1.20-7.10, p = 0.02) were detected as risk factors for the development of OINV. Conclusion: This study revealed a high incidence of OINV during opioid dose escalation, indicating that careful monitoring is required as at the time of opioid introduction. Further validation by a prospective study is required.

Simulation of drug-drug interactions between breast cancer chemotherapeutic agents and antiemetic drugs

BACKGROUND

Chemotherapy-induced nausea and vomiting are commonly experienced side effects in breast cancer (BCa) patients. Antiemetic drugs used in BCa treatment are either inhibitors or inducers of cytochrome P450 (CYP) enzymes, while anticancer drugs are metabolized by CYPs.

OBJECTIVES

The purpose of the present work was to evaluate in silico drug-drug interaction (DDI) potential between BCa chemotherapeutic drugs and antiemetic agents.

METHODS

The Drug-Drug Interaction™ module of GastroPlus™ was employed to assess CYP-related interactions between antiemetic and anticancer therapy combinations. The CYP inhibitory or inducing parameters (IC50, Ki, EC50) used in simulations were obtained from the literature.

RESULTS

Analyses of twenty-three BCa drugs indicated that 22% of the chemotherapeutic drugs do not need an antiemetic agent due to their low emetogenicity, whereas 30% of the anticancer drugs are not metabolized by CYPs. The remaining eleven anticancer drugs metabolized by CYPs generated ninety-nine combinations with nine antiemetics. Simulation of DDIs suggest that about half of the pairs did not demonstrate any potential for DDI, whereas 30%, 10%, and 9% of the pairs showed weak, moderate, and strong interaction potential, respectively. In the present study, netupitant was the only antiemetic that showed strong inhibitory interactions (predicted AUC ratio > 5) with CYP3A4-metabolzied anticancer therapies (e.g., docetaxel, ribociclib, olaparib). Moderate to no interactions were observed with ondansetron, aprepitant, rolapitant, and dexamethasone in combination with anticancer agents.

CONCLUSION

It is critical to recognize that these interactions can get amplified in cancer patients because of the severity of the disease and chemotherapy toxicities. Clinicians need to be aware of the DDI likelihood of the drug combinations used in BCa treatment.

Associations of plasma aprepitant and its N-dealkylated metabolite with cachexia status and clinical responses in head and neck cancer patients

PURPOSE

Oral aprepitant has a large interindividual variation in clinical responses in advanced cancer. This study aimed to characterize plasma aprepitant and its N-dealkylated metabolite (ND-AP) based on the cachexia status and clinical responses in head and neck cancer patients.

METHODS

Fifty-three head and neck cancer patients receiving cisplatin-based chemotherapy with oral aprepitant were enrolled. Plasma concentrations of total and free aprepitant and ND-AP were determined at 24 h after a 3-day aprepitant treatment. The clinical responses to aprepitant and degrees of cachexia status were assessed using a questionnaire and Glasgow Prognostic Score (GPS).

RESULTS

Serum albumin level was negatively correlated with the plasma concentrations of total and free aprepitant but not ND-AP. The serum albumin level had a negative correlation with the metabolic ratio of aprepitant. The patients with GPS 1 or 2 had higher plasma concentrations of total and free aprepitant than those with GPS 0. No difference was observed in the plasma concentration of ND-AP between the GPS classifications. The plasma interleukin-6 level was higher in patients with GPS 1 or 2 than 0. The absolute plasma concentration of free ND-AP was higher in patients without the delayed nausea, and its concentration to determine the occurrence was 18.9 ng/mL. The occurrence of delayed nausea had no relation with absolute plasma aprepitant.

CONCLUSION

Cancer patients with a lower serum albumin and progressive cachectic condition had a higher plasma aprepitant level. In contrast, plasma free ND-AP but not aprepitant was related to the antiemetic efficacy of oral aprepitant.

A pharmacological overview of aprepitant for the prevention of postoperative nausea and vomiting

INTRODUCTION

Post-operative nausea and vomiting (PONV) affects 30% of all patients undergoing surgery and up to 80% of high-risk patients. Antiemetics for PONV prophylaxis target a variety of receptor systems, with varying degrees of efficacy and side effect profile. Neurokinin -1 receptor antagonists are the most recent class of compounds investigated for PONV prophylaxis, with aprepitant being the only one currently approved for this indication.

AREAS COVERED

This review covers the pathophysiology of PONV, current recommendations for PONV prophylaxis, pharmacokinetics, and pharmacodynamics of aprepitant, and the evidence for its efficacy in the management of PONV as a single agent and in combination therapy.

EXPERT OPINION

Aprepitant is effective for PONV prophylaxis. It has superior antivomiting efficacy, long half-life, and favorable side effect profile. Data on antiemetic combinations involving aprepitant are limited, and it not clear if the addition of other antiemetics to aprepitant result in improved PONV prophylaxis. The oral route of administration of aprepitant is a potential limitation in a busy clinical practice. However, the recent approval of an intravenous formulation could provide a more convenient route of administration. Aprepitant remains more expensive than other antiemetics, and there are no studies assessing the cost effectiveness of its use.

Population pharmacokinetic analysis reveals no impact of aprepitant on the pharmacokinetics of ifosfamide, 2-dechloroifosfamide, and 3-dechloroifosfamide

PURPOSE

Several case reports and retrospective series have clearly pointed to the role of aprepitant, an antiemetic drug, in the development of encephalopathy when used with ifosfamide. Described as an inhibitor of several CYP metabolic pathways, aprepitant is suspected of drug-drug-interaction on ifosfamide pharmacokinetics. The pharmacokinetics of ifosfamide and two of its metabolites (2-dechloroifosfamide and 3-dechloroifosfamide) was studied in patients with soft tissue sarcomas to evaluate the impact of aprepitant administration.

METHODS

A population pharmacokinetic approach was applied to analyze data obtained in 42 patients at cycle 1 (without aprepitant) and cycle 2 (with aprepitant for 34 of them).

RESULTS

A previously published pharmacokinetic model including a time-dependency process well fit the data. Aprepitant had no impact on ifosfamide or its two metabolite pharmacokinetic parameters.

CONCLUSION

This study suggests that aprepitant does not lead to a significant modification of ifosfamide metabolization, even though other metabolites such as 4 hydroxyifosfamide and chloroacetaldehyde were not monitored in this study.

Evaluation of hepatic CYP3A enzyme activity using endogenous markers in lung cancer patients treated with cisplatin, dexamethasone, and aprepitant

PURPOSE

Aprepitant is used with dexamethasone and 5-HT₃ receptor antagonists as an antiemetic treatment for chemotherapy, including cisplatin. Aprepitant is a substrate of cytochrome P450 (CYP) 3A4 and is known to cause its inhibition and induction. In addition, dexamethasone is a CYP3A4 substrate that induces CYP3A4 and CYP3A5 expression. In this study, we aimed to quantitatively evaluate the profile of CYP3A activity using its endogenous markers in non-small cell lung cancer patients receiving a standard cisplatin regimen with antiemetics, including aprepitant.

METHODS

Urinary 11β-hydroxytestosterone (11β-OHT)/testosterone concentration ratio and plasma 4β-hydroxycholesterol (4β-OHC) concentrations were measured before and after cisplatin treatment (days 1, 4, and 8). CYP3A5 was genotyped, and plasma aprepitant concentrations were measured on day 4 to examine its influence on CYP3A endogenous markers.

RESULTS

The urinary 11β-OHT/testosterone concentration ratio in the 35 patients included in this study increased by 2.65-fold and 1.21-fold on days 4 and 8 compared with day 1, respectively. Their plasma 4β-OHC concentration increased by 1.46-fold and 1.66-fold, respectively. The mean plasma aprepitant concentration on day 4 was 1,451 ng/mL, which is far lower than its inhibitory constant. The allele frequencies of CYP3A5*1 and CYP3A5*3 were 0.229 and 0.771, respectively. In patients with the CYP3A5*1 allele, the plasma 4β-OHC concentration was significantly lower at baseline but more potently increased with chemotherapy.

CONCLUSION

CYP3A activity was significantly induced from day 4 to day 8 in patients receiving cisplatin and three antiemetic drugs.

Simple Liquid Chromatography-Tandem Mass Spectrometry Method for Quantitation of Total and Free Aprepitant and Its Active N-Dealkylated Metabolites in Human Plasma

BACKGROUND

Aprepitant, an antiemetic selective neurokinin-1 receptor antagonist, is primarily metabolized to the active N-dealkylated form (ND-AP) and then converted to its carbonyl form (ND-CAP) in humans. This study developed a simple liquid chromatography-tandem mass spectrometry method using electrospray ionization for the quantitation of plasma total and free aprepitant and its N-dealkylated metabolites and used them to analyze patient plasma.

METHODS

Free aprepitant and ND-AP in plasma were fractionated using centrifugal ultrafiltration. The analytes in plasma or their ultrafiltered specimens treated with triethylamine/acetonitrile were isocratically separated using a 3-μm octadecylsilyl column with a total run time of 10 minutes and scanned using positive ion electrospray ionization.

RESULTS

The calibration curves of total aprepitant, ND-AP, and ND-CAP were prepared at concentration ranges of 50-2500, 20-1000, and 5-250 ng/mL, respectively, whereas that of free aprepitant and ND-AP were at a concentration range of 2-150 ng/mL. The intraassay and interassay accuracy and imprecision values were 93.5%-107.7% and 94.6%-103.3%, and 2.1%-7.5% and 1.0%-8.9%, respectively. Aprepitant and its metabolites did not exhibit any matrix effects or instabilities in the plasma specimens. In cancer patients receiving oral aprepitant, the plasma concentration ranges of total aprepitant, ND-AP, and ND-CAP, and free aprepitant and ND-AP were 137-2170, 104-928, 22.4-97.6, 8.11-60.0, and 3.53-56.0 ng/mL, respectively. The median plasma free fraction proportion of aprepitant and ND-AP was 4.14% and 4.90%, respectively.

CONCLUSIONS

The present developed method showed an acceptable analytical performance and can be used to evaluate total and free aprepitant and its N-dealkylated metabolites in patient plasma.

Pharmacokinetics of Dexamethasone when Administered with Fosaprepitant for Chemotherapy-Induced Nausea and Vomiting and Differences in Dose-Dependent Antiemetic Effects

BACKGROUND

Fosaprepitant, an NK1 receptor antagonist, inhibits and induces cytochrome P450 3A4 (CYP3A4) as its substrate. Contrarily dexamethasone is metabolized by CYP3A4. Therefore, in combination therapy wherein both agents interact with each other, it is recommended that the dexamethasone dose be reduced in the first two days. Thus far, there are only a few studies on the optimum dose of dexamethasone after day 3. Thus, we aimed to determine the pharmacokinetics of dexamethasone on day3 when administered together with fosaprepitant and investigate the dose-dependent differences in its antiemetic effect in patients with cancer.

METHODS

Twelve patients with esophageal, stomach, or lung cancer received primary highly emetogenic chemotherapy (HEC). We intravenously administered 9.9 mg and 6.6 mg of dexamethasone on days 1 and 2, respectively, and 6.6 mg or 13.2 mg on day 3 together with the administration of 150 mg fosaprepitant and 0.75 mg palonosetron. We assessed the pharmacokinetics of dexamethasone on day 3 by dose and examined the dose-dependent antiemetic effect.

RESULTS

No differences were observed in the time-to-maximum concentration and blood half-life of dexamethasone between patient groups that received dexamethasone at doses of 6.6 mg and 13.2 mg. In contrast, the area under the blood concentration-time curve and the maximum concentration of dexamethasone correlated with its dose. Moreover, the blood dexamethasone concentration on day 3 increased by twofold after the administration of a higher dose than after a lower dose. The severity of nausea in the delayed phase significantly decreased in a dose-dependent manner.

CONCLUSION

Administration of a higher dexamethasone dose on day 3 improved the antiemetic effect of the combined regimen in patients with cancer who underwent HEC.<br />.

Understanding Mechanisms of Food Effect and Developing Reliable PBPK Models Using a Middle-out Approach

Over the last 10 years, 40% of approved oral drugs exhibited a significant effect of food on their pharmacokinetics (PK) and currently the only method to characterize the effect of food on drug absorption, which is recognized by the authorities, is to conduct a clinical evaluation. Within the pharmaceutical industry, there is a significant effort to predict the mechanism and clinical relevance of a food effect. Physiologically based pharmacokinetic (PBPK) models combining both drug-specific and physiology-specific data have been used to predict the effect of food on absorption and to reveal the underlying mechanisms. This manuscript provides detailed descriptions of how a middle-out modeling approach, combining bottom-up in vitro-based predictions with limited top-down fitting of key model parameters for clinical data, can be successfully used to predict the magnitude and direction of food effect when it is predicted poorly by a bottom-up approach. For nefazodone, a mechanistic clearance for the gut and liver was added, for furosemide, an absorption window was introduced, and for aprepitant, the biorelevant solubility was refined using multiple solubility measurements. In all cases, these adjustments were supported by literature data and showcased a rational approach to assess the factors limiting absorption and exposure.

Reversible Mechanisms of Enzyme Inhibition and Resulting Clinical Significance

Inhibition of a drug-metabolizing enzyme by the reversible interaction of a drug with the enzyme, thus decreasing the metabolism of another drug, is a major cause of clinically significant drug-drug interactions. This chapter defines the four reversible mechanisms of inhibition exhibited by drugs: competitive, noncompetitive, uncompetitive, and mixed competitive/noncompetitive. An in vitro procedure to determine the potential of a drug to be a reversible inhibitor is also provided. Finally, a number of examples of clinically significant drug-drug interactions resulting from reversible inhibition are described.

Evaluation of tradipitant, a selective NK1 antagonist, on response to oxycodone in humans

RATIONALE

Preclinical studies demonstrate that the NK1 receptor is involved in opioid reinforcement and withdrawal expression. Few studies have examined the impact of treatment with NK1 antagonists on opioid response in humans.

OBJECTIVE

To explore the potential for a selective NK1 antagonist, tradipitant, to attenuate the abuse liability and reinforcing and analgesic effects of oxycodone in opioid-experienced individuals.

METHODS

Participants with recreational opioid use, but without opioid physical dependence, were enrolled as inpatients for ~6 weeks (n = 8). A within-subject, double-blind, randomized, placebo-controlled, crossover design was employed. The pharmacodynamic response to intranasal oxycodone across a range of doses (0 to 30 mg) was examined during two counterbalanced maintenance periods (tradipitant 0 or 85 mg/bid). Oxycodone self-administration was assessed with a modified progressive ratio procedure, and analgesia was assessed with the cold pressor test.

RESULTS

Oxycodone produced significant and dose-related increases on a broad array of prototypic opioid measures, including subjective ratings related to abuse liability (e.g., liking) and physiological outcomes (i.e., expired CO₂). Oxycodone self-administration increased with increasing dose, as did analgesia. Tradipitant largely did not alter any of these effects of oxycodone, with the exception of producing a reduction in ratings of desire for opioids.

CONCLUSIONS

Given that the vast majority of oxycodone effects were unchanged by tradipitant, these data do not provide support for the utility of NK1 antagonists as a potential treatment for opioid use disorder.

Chemotherapy-Induced Nausea and Vomiting: Pathogenesis, Recommendations, and New Trends

The significant physical and emotional effects of chemotherapy-induced nausea and vomiting (CINV) are experienced by cancer patients. Severe symptoms decrease the patient's quality of life and potentially deters further treatment. The five main forms of CINV (i.e., acute, delayed, anticipatory, breakthrough, and refractory) require different treatment regimens, which often include 5-HT3 receptor antagonists, NK1 receptor antagonists, and corticosteroids. Despite a significant amount of research and development of antiemetic agents, management of CINV remains a great challenge with many needs waiting to be adequately addressed, such as controlling non-acute CINV, developing appropriate CINV treatment protocols for multiple-day chemotherapy patients, and providing options for those prone to CINV despite treatment. Further research is required to optimize CINV management for these patients.

Intestinal absorption of BCS class II drugs administered as nanoparticles: A review based on in vivo data from intestinal perfusion models

An established pharmaceutical strategy to increase oral drug absorption of low solubility–high permeability drugs is to create nanoparticles of them. Reducing the size of the solid-state particles increases their dissolution and transport rate across the mucus barrier and the aqueous boundary layer. Suspensions of nanoparticles also sometimes behave differently than those of larger particles in the fed state. This review compares the absorption mechanisms of nano- and larger particles in the lumen at different prandial states, with an emphasis on data derived from in vivo models. Four BSC class II drugs—aprepitant, cyclosporine, danazol and fenofibrate—are discussed in detail based on information from preclinical intestinal perfusion models.

Modeling and Simulation Analysis of Aprepitant Pharmacokinetics in Pediatric Patients With Postoperative or Chemotherapy-Induced Nausea and Vomiting

OBJECTIVES

Aprepitant is effective for the prevention of chemotherapy-induced or postoperative nausea and vomiting (CINV/PONV). The aim of this study was to develop a population pharmacokinetic (PK) model of aprepitant in pediatric patients and to support dosing recommendations for oral aprepitant in pediatric patients at risk of CINV.

METHODS

A population PK model was constructed based on data from 3 clinical studies in which children (6 months to 12 years) and adolescents (12–19 years) were treated with a 3-day regimen of oral aprepitant (capsules or suspension), with or without intravenous fosaprepitant on day 1 (CINV), or a single dose of oral aprepitant (capsules or suspension; PONV). Nonlinear mixed-effects modeling was used for model development, and a stepwise covariate search determined factors influencing PK parameters. Simulations were performed to guide final dosing strategies of aprepitant in pediatric patients.

RESULTS

The analysis included 1326 aprepitant plasma concentrations from 147 patients. Aprepitant PK was described by a 2-compartment model with linear elimination and first-order absorption, with allometric scaling for central and peripheral clearance and volume using body weight, and a cytochrome P450 3A4 maturation component for the effect of ontogeny on systemic clearance. Simulations established that application of a weight-based (for those &lt;12 years) and fixed-dose (for those 12–17 years) dosing regimen results in comparable exposures to those observed in adults.

CONCLUSIONS

The developed population PK model adequately described aprepitant PK across a broad pediatric population, justifying fixed (adult) dosing for adolescents and weight-based dosing of oral aprepitant for children.

Comparison of Pharmacokinetics of Aprepitant in Healthy Chinese and Caucasian Subjects

Purpose

Aprepitant is used to prevent nausea and vomiting associated with moderately and highly emetogenic chemotherapy. In this open-label, 2-period study, the safety, tolerability, and pharmacokinetics (PK) of aprepitant (EMEND^®) were evaluated in healthy Chinese and Caucasian subjects.

Patients and Methods

Twelve Chinese and 12 Caucasian subjects were to receive a 125 mg single-dose of aprepitant during period 1; subsequently, after 15 days washout, only Chinese subjects were to receive the 3-day regimen in period 2. In each period, serial blood samples were collected and analyzed by a validated liquid chromatographic and mass spectrometric method to characterize aprepitant PK across both groups.

Results

In both Chinese and Caucasian subjects, there were no serious adverse events. AUC_0-∞, C_max, T_max, and t_1/2 were largely comparable between the two ethnicities. Comparing the result of period 1 in Chinese and Caucasian subjects, the geometric least-squares mean maximum plasma concentrations (C_max) were 1482 ng/mL and 1435 ng/mL, and the area under the concentration–time curve (AUC_0-∞) 34,035 hr·ng/mL and 34,188 hr·ng/mL. In period 2, the geometric mean AUC_0–24 on Day 1 and Day 3 were 19,446 hr·ng/mL and 27,843 hr·ng/mL, and the geometric mean C_max on Day 1 and Day 3 were 1423 ng/mL and 1757 ng/mL, respectively.

Conclusion

Aprepitant is generally safe and well tolerated in healthy Chinese and Caucasian subjects. Aprepitant PK is comparable between Chinese and Caucasian subjects following single-dose administration. The PK following a clinical 3-day regimen on healthy Chinese subjects has been characterized.

Morpholine as ubiquitous pharmacophore in medicinal chemistry: Deep insight into the structure-activity relationship (SAR)

Morpholine is a versatile moiety, a privileged pharmacophore and an outstanding heterocyclic motif with wide ranges of pharmacological activities due to different mechanisms of action. The ability of morpholine to enhance the potency of the molecule through molecular interactions with the target protein (kinases) or to modulate the pharmacokinetic properties propelled medicinal chemists and researchers to synthesize morpholine ring by the efficient ways and to incorporate this moiety to develop various lead compounds with diverse therapeutic activities. The present review primarily focused on discussing the most promising synthetic leads containing morpholine ring along with structure-activity relationship (SAR) to reveal the active pharmacophores accountable for anticancer, anti-inflammatory, antiviral, anticonvulsant, antihyperlipidemic, antioxidant, antimicrobial and antileishmanial activity. This review outlines some of the recent effective chemical synthesis for morpholine ring. The review also highlighted the metabolic liability of some clinical drugs containing this nucleus and various researches on modified morpholine to enhance the metabolic stability of drugs as well. Drugs bearing morpholine ring and those under clinical trials are also mentioned with the role of morpholine and their mechanism of action. This review will provide the necessary knowledge base to the medicinal chemists in making strategic structural changes in designing morpholine derivatives.

Divergent synthesis of oxazolidines and morpholines via PhI(OAc)2-mediated difunctionalization of alkenes

Herein we describe the PhI(OAc)₂-mediated 1,1- and 1,2-difunctionalization of alkenes with N-tosyl amino alcohols to form oxazolidine and morpholine derivatives.

Evaluation of Dissolution Enhancement of Aprepitant Drug in Ternary Pharmaceutical Solid Dispersions with Soluplus® and Poloxamer 188 Prepared by Melt Mixing

In the present study Aprepitant (APT) ternary solid dispersions (SDs) were developed and evaluated for the first time. Specifically, ternary SDs of APT with Poloxamer 188 and Soluplus® (SOL) were prepared via melt mixing and compared to binary APT/Poloxamer 188 and APT/SOL SDs. Initially, combined thermo-gravimetric and hot-stage polarized light microscopy studies indicated that all tested compounds were thermally stable up to 280 °C, while Poloxamer 188 acted as a plasticizer to SOL by significantly reducing the temperature required to fully solubilize the API during SD preparation. Differential scanning calorimetry combined with wide angle X-ray diffraction studies showed that crystalline API was dispersed in both binary and ternary SDs, while Fourier transformation-infrared spectroscopy studies revealed no molecular interactions among the components. Scanning electron microscopy combined with EDAX element analysis showed that the API was dispersed in nano-scale within the polymer matrices, while increasing APT content led to increasing API nano-crystals within the SDs. Finally, dissolution studies showed that the prepared formulations enhanced dissolution of Aprepitant and its mechanism analysis was further studied. A mathematical model was also investigated to evaluate the drug release mechanism.

The NK1 receptor antagonist serlopitant for treatment of chronic pruritus

Introduction: Pruritus is a common symptom associated with several potential underlying causes, including both dermatologic and systemic diseases; it can also occur without an identifiable cause. Current treatment options are limited and most patients experience impaired quality of life. Serlopitant is a neurokinin 1 (NK₁) receptor antagonist under development for the treatment of pruritus associated with various dermatologic conditions and chronic pruritus of unknown origin. Areas covered: This review describes the epidemiology and unmet needs of patients with chronic pruritus, focusing specifically on patients with prurigo nodularis, psoriatic itch, and chronic pruritus of unknown origin; the rationale for targeting the NK₁ receptor for treatment of chronic pruritus; and the clinical development of serlopitant, including efficacy and safety data from completed phase II studies. Expert opinion: There is an unmet need for novel, safe, and effective therapies to treat chronic pruritus. Serlopitant has shown promising efficacy, safety, and tolerability across different patient populations, including adolescents and elderly patients. In contrast to less convenient administration options, serlopitant is a once-daily oral tablet, which is expected to facilitate compliance.

Neurokinin-1 receptor antagonists: review of their role for the prevention of chemotherapy-induced nausea and vomiting in adults

Introduction: The addition of neurokinin-1 receptor antagonists (NK₁RAs) to standard prophylaxis of 5-hydroxytryptamine-3 RA (5-HT₃RA) plus dexamethasone more effectively prevents chemotherapy-induced nausea and vomiting (CINV) associated with highly and moderately emetogenic chemotherapy. Areas covered: This review presents the evidence base for the use of oral and intravenous (IV) NK₁RAs, focusing on the pharmacologic and clinical properties as a class, and highlighting differences between agents. A PubMed literature search was conducted from 2000 to 2018. Expert opinion: Adherence to international antiemetic guidelines remains a clinical challenge. Strategies to simplify antiemetic regimens and facilitate their administration may improve compliance and treatment outcomes. The use of fixed-combination antiemetics offers clinical utility, in combining an NK₁RA with a 5-HT₃RA in a single oral dose. The use of long-lasting NK₁RAs and administering CINV prophylaxis closer to the time of chemotherapy may also assist with guideline and treatment compliance, diminishing the need for home-based administration, and potentially reducing resource utilization. The availability of IV and oral formulations of NK₁RAs and NK₁RA-5-HT₃RA fixed combinations offers further utility, particularly for those patients unsuited for oral administration. However, safety considerations with respect to injection site toxicity and hypersensitivity reactions of the new NK₁RA IV formulations deserve close attention.

Aprepitant Drug in Ternary Pharmaceutical Solid Dispersions with Soluplus® and Poloxamer 188 Prepared by Melt Mixing

In the present study Aprepitant (APT) ternary solid dispersions (SDs) were developed and evaluated for the first time. Specifically, ternary SDs of APT with Poloxamer 188 and Soluplus® (SOL) were prepared via melt mixing and compared to binary APT/Poloxamer 188 and APT/SOL SDs. Initially, combined thermo-gravimetric and hot-stage polarized light microscopy studies indicated that all tested compounds were thermally stable up to 280 °C, while Poloxamer 188 acted as a plasticizer to SOL by significantly reducing the temperature required to fully solubilize the API during SD preparation. Differential scanning calorimetry combined with wide angle X-ray diffraction studies showed that crystalline API was dispersed in both binary and ternary SDs, while Fourier transformation-infrared spectroscopy studies revealed no molecular interactions among the components. Scanning electron microscopy combined with EDAX element analysis showed that the API was dispersed in nano-scale within the polymer matrices, while increasing APT content led to increasing API nano-crystals within the SDs. Finally, dissolution studies showed that the prepared formulations enhanced dissolution of Aprepitant and its mechanism analysis was further studied. A mathematical model was also investigated to evaluate the drug release mechanism

Efficacy, Tolerability and Pharmacokinetic Impact of Aprepitant in Sarcoma Patients Receiving Ifosfamide and Doxorubicin Chemotherapy: A Randomized Controlled Trial

INTRODUCTION

Aprepitant, a selective neurokinin-1 receptor antagonist approved for prevention of chemotherapy-induced nausea and vomiting (CINV), is an inhibitor of the cytochrome P450 3A4 (CYP3A4) enzyme, which is involved in the clearance of several chemotherapeutic agents. Here we evaluated the efficacy and toxicity of a combination of aprepitant, palonosetron, and dexamethasone as antiemetic prophylaxis in sarcoma patients receiving ifosfamide and doxorubicin chemotherapy, and examined the potential of aprepitant to affect the pharmacokinetics of ifosfamide, which is primarily metabolized by CYP3A4.

METHODS

A total of 108 sarcoma patients were randomly assigned to either the aprepitant group (antiemetic regimen: aprepitant, palonosetron, and dexamethasone) or the control group (antiemetic regimen: palonosetron and dexamethasone). Data on nausea, vomiting, and use of rescue medication were collected, and the primary efficacy end point was the proportion of patients with complete response (CR), defined as no vomiting and no use of rescue therapy during 120 h after initiation of chemotherapy. Tolerability was evaluated on the basis of reported adverse events and laboratory assessments. Blood samples for ifosfamide pharmacokinetic analysis were collected in ten patients.

RESULTS

The percentage of patients achieving CR was significantly higher in the aprepitant group compared with that in the control group in the acute, delay, and overall phase (78.4% vs. 59.3%, 74.5% vs. 48.1%, and 68.6% vs. 37.0%, p < 0.05, respectively). No significant differences of adverse events or hematological toxicity were detected between the two groups. Concomitant administration of aprepitant did not cause any statistically significant changes in ifosfamide pharmacokinetics. Values for aprepitant group vs. control group were as follows: geometric mean of C_max was 119 vs. 120 ng/mL, AUC_0-last was 648 vs. 635 ng h/mL, AUC_0-inf was 681 vs. 668 ng h/mL, plasma clearance was 4.40 vs. 4.49 (L/h/m²), respectively; harmonic means of t_1/2 was 2.11 vs. 2.25 h.

CONCLUSIONS

This study showed that aprepitant in combination with palonosetron and dexamethasone was safe and effectively controlled CINV in sarcoma patients receiving ifosfamide and doxorubicin chemotherapy. Aprepitant may have a low potential to affect the pharmacokinetics of chemotherapeutic agents metabolized by CYP3A4.

Nightmares and hallucinations with aprepitant and opium powder: a suspected drug-drug interaction

Polypharmacy of elderly oncology patients and fragmented medication management are well-known risk factors for drug-drug interactions (DDIs). These interactions can occur among antineoplastic, ongoing chronic treatment(s) and chemotherapy-associated treatments, like antiemetics. Clinically relevant interactions based on enzyme- or transporter-inhibition phenomena of active drugs can increase the frequency of their DDIs. We describe a strongly suspected elderly cancer patient's DDI between aprepitant and opium powder in the context of an irinotecan-based regimen manifested by nightmares and visual hallucinations. We discuss this DDI's hypothetical pharmacological mechanisms and management.

Acute chemotherapy-induced nausea and vomiting in children with cancer: Still waiting for a common consensus on treatment

Chemotherapy-induced nausea and vomiting (CINV) is one of the most common treatment side-effects, and remains a significant concern, in children undergoing chemotherapy. Although adult patients receive chemotherapy regimens combined with appropriate standardized antiemetic treatment, children can receive markedly varying antiemetic treatments. A narrative review of CINV was performed regarding CINV definition, scoring system, prevention and treatment, specifically focussing on studies conducted with paediatric oncology patients. The review highlighted a lack of rigorously developed CINV scoring systems and standardized CINV pharmacological treatment for paediatric oncology patients. Different scoring systems were found to identify potential risk factors for CINV associated with the use of several different antiemetic drugs, however, few studies have been performed in children undergoing chemotherapy. Thus, CINV remains a distressing and partially controlled side-effect in the paediatric patient population. To reduce emesis and improve quality of life in paediatric oncology patients, standardized antiemetic treatment may be preferred, using a unique CINV scoring system that accounts for the emetogenic level of the chemotherapy regimen adopted and the children's clinical characteristics.

NK1 receptor antagonists for depression: Why a validated concept was abandoned

BACKGROUND

NK1 receptor antagonists were abandoned despite antidepressant efficacy in five randomized clinical trials. The loss of confidence may be attributed to the failure of a Phase III clinical program with the NK1 receptor antagonist aprepitant in Major Depression. This review examines how PET receptor occupancy was used to select doses for aprepitant and that these may not have achieved adequate exposure.

METHODS

PubMed, Google Scholar, and FDA databases were searched for articles concerning NK1 receptor antagonists, human PET receptor occupancy and clinical trials in Major Depression.

RESULTS

Antidepressant efficacy was initially demonstrated with three NK1 receptor antagonists, including aprepitant. A nanoparticle formulation of aprepitant was then developed to improve oral bioavailability. In PET studies, doses of 80 and 160mg achieved a high level (~ 90%) of occupancy of NK1 receptors in the human brain and were selected for Phase III. The efficacy of these doses of the nanoparticle formulation may not have been established in depressed patients prior to Phase III, and previous formulations required a dose of 300mg of aprepitant for efficacy. No antidepressant effect of 80 or 160mg of aprepitant was found, and it was concluded that the NK1 antagonist concept was flawed. However, subsequent studies with other compounds showed that a higher level of NK1 receptor occupancy (100%) was required for antidepressant efficacy.

LIMITATIONS

Key data concerning the bioequivalence of different formulations of aprepitant have not been published. The importance of NK1 antagonists for pharmacotherapy of depression and other psychiatric disorders has not been established in clinical practice.

CONCLUSION

Aprepitant may have failed in Phase III because of an inadequate understanding of the relationship between brain NK1 receptor occupancy and clinical response. A validated and novel mechanistic approach to treat depression has been misperceived as ineffective and abandoned. Caution should be exercised in the appropriate use of PET occupancy data to select doses for drug development programs in neuropsychiatry. The relationship between exposure, receptor occupancy and clinical response should be established. A crisis of confidence has followed the failure of this and other programs in neuropsychiatry, with a far reaching and detrimental impact on pharmaceutical research.

Neurokinin 1 receptor antagonists in the prevention of chemotherapy-induced nausea and vomiting: focus on fosaprepitant

Chemotherapy-induced nausea and vomiting (CINV) remains a challenge in cancer care. Improved understanding of CINV pathophysiology has triggered the development of new antiemetic therapeutic options, such as selective neurokinin-1 (NK₁) receptor antagonists (RAs), which effectively prevent CINV when added to a standard antiemetic regimen (serotonin-3 RA and dexamethasone). Aprepitant and its water-soluble prodrug, fosaprepitant dimeglumine, are the most widely used NK₁ RAs, with extensive clinical use worldwide. Recently, a Phase III trial prospectively evaluated fosaprepitant-based antiemetic therapy for CINV prevention in a large, well-defined nonanthracycline- and cyclophosphamide-based moderately emetogenic chemotherapy population. Fosaprepitant demonstrated significantly improved efficacy outcomes compared with a control regimen and was generally well tolerated, indicating that NK₁ RAs are a valuable therapeutic option in this setting.

Recent developments in the clinical pharmacology of rolapitant: subanalyses in specific populations

Knowledge of the involvement of the neurokinin substance P in emesis has led to the development of the neurokinin-1 receptor antagonists (NK-1 RAs) for control of chemotherapy-induced nausea and vomiting (CINV), in combination with serotonin type 3 receptor antagonists and corticosteroids. The NK-1 RA rolapitant, recently approved in oral formulation, has nanomolar affinity for the NK-1 receptor, as do the other commercially available NK-1 RAs, aprepitant and netupitant. Rolapitant is rapidly absorbed and has a long half-life in comparison to aprepitant and netupitant. All three NK-1 RAs undergo metabolism by cytochrome P450 (CYP) 3A4, necessitating caution with the concomitant use of CYP3A4 inhibitors, but in contrast to aprepitant and netupitant, rolapitant does not inhibit or induce CYP3A4. However, rolapitant is a moderate inhibitor of CYP2D6, and concomitant use with CYP2D6 substrates with narrow therapeutic indices should be avoided. Aprepitant, netupitant, and rolapitant have all demonstrated efficacy in the control of delayed CINV in patients receiving moderately and highly emetogenic chemotherapy in randomized controlled trials, including over multiple cycles of chemotherapy. We reviewed recent post hoc analyses of clinical trial data demonstrating that rolapitant is efficacious in the control of CINV in patient populations with specific tumor types, namely, breast cancers, gastrointestinal/colorectal cancers, and lung cancers. In addition, we show that rolapitant has efficacy in the control of CINV in specific age groups of patients receiving chemotherapy (<65 and ≥65 years of age). Overall, the safety profile of rolapitant in these specific patient populations was consistent with that observed in primary analyses of phase 3 trials.

Genetic Risk Factors Associated With Antiemetic Efficacy of Palonosetron, Aprepitant, and Dexamethasone in Japanese Breast Cancer Patients Treated With Anthracycline-based Chemotherapy

INTRODUCTION

Breast cancer patients often receive anthracycline-based chemotherapy, and chemotherapy-induced nausea and vomiting (CINV) remains one of the most uncomfortable and distressing adverse reactions. Poor control of CINV reduces the relative dose intensity of chemotherapy agents, which has been associated with poor clinical outcomes and shorter survival. The aim of the present study was to identify genetic risk factors associated with anthracycline-based CINV.

PATIENTS AND METHODS

We evaluated CINV attributable to anthracycline-based chemotherapy in Japanese breast cancer patients treated with an antiemetic regimen that included palonosetron, aprepitant, and dexamethasone. Furthermore, we investigated the associations between CINV and single nucleotide polymorphisms in 6 candidate genes.

RESULTS

Emesis episodes were rarely observed in the 125 patients included in the present survey (7.2%; n = 9); however, significant nausea occurred in more than one half of the patients (52.8%; n = 66). In particular, acute significant nausea was not effectively controlled. Multivariate logistic regression analysis revealed that the ABCG2 (rs2231142) AA genotype is significantly associated with acute significant nausea (odds ratio, 4.87; 95% confidence interval, 1.01-23.60; P = .049).

CONCLUSION

The findings of the present study provide significant insights for developing personalized antiemetic strategies for breast cancer patients receiving anthracycline-based chemotherapy.

The safety of antiangiogenic agents and PARP inhibitors in platinum-sensitive recurrent ovarian cancer

INTRODUCTION

Recurrence is a common event in endothelial ovarian cancer (EOC) patients, and the choice of the most appropriate treatment is driven by the platinum-free interval, molecular characteristics of the disease such as BRCA mutational status, previous treatments and toxicity. Areas covered: This review focuses on the main hematologic and non-hematologic toxicities correlated with the use of licensed antiangiogenic agents and PARP inhibitors in recurrent platinum-sensitive EOC, providing recommendations for their management. Expert opinion: The clinical research over the next years will be focused on a more precise characterization of molecular pathways underlying tumorigenesis of the five ovarian tumors, to improve the decision-making process in these rare diseases. For this purpose, new study designs and international collaborations will become mandatory. Immunotherapy, antiangiogenic agents and PARP inhibitors will be combined to build a treatment strategy algorithm which will allow patients to receive all the available treatment option, in the more appropriate sequence.

2016 updated MASCC/ESMO consensus recommendations: Prevention of acute chemotherapy-induced nausea and vomiting in children

PURPOSE

To update the 2009 recommendations for the prevention of acute chemotherapy-induced emesis in children.

METHODS

We updated the original systematic literature search. Randomized studies were included in the evidence to support this guideline if they were primary studies fully published in full text in English or French; included only children less than 18 years old or, for mixed studies of adults and children, reported the pediatric results separately or the median or mean age was no more than 13 years; evaluated acute chemotherapy-induced nausea and vomiting (CINV) prophylaxis; provided sufficient information to permit determination of the emetogenicity of the antineoplastic therapy administered or the study investigators stated the emetogenicity of the chemotherapy administered; included an implicit or explicit definition of complete acute CINV response; described the antiemetic regimen in full; and reported the complete acute CINV response rate as a proportion.

RESULTS

Twenty-five randomized studies, including eight published since 2009, met the criteria for inclusion in this systematic review. Prophylaxis with a 5-HT3 antagonist (granisetron or ondansetron or palonosetron or tropisetron) ± dexamethasone ± aprepitant is recommended for children receiving highly or moderately emetogenic chemotherapy. For children receiving chemotherapy of low emetogenicity, a 5-HT3 antagonist is recommended.

CONCLUSIONS

The findings of several randomized trials were used to update recommendations for the prevention of acute CINV. However, significant research gaps remain and must be addressed before CINV control in children can be optimized.

Rolapitant for the treatment of chemotherapy-induced nausea and vomiting: a review of the clinical evidence

Chemotherapy-induced nausea and vomiting (CINV), both acute and delayed, has a dramatic effect on the well-being and quality of life of patients with cancer. Improved understanding of the mechanisms involved in CINV has led to the development of agents targeting the 5-HT3 receptor as well as the NK-1 receptor. Antiemetic prophylaxis given to patients receiving highly emetogenic chemotherapy combines agents blocking the 5-HT3 and NK-1 receptors along with corticosteroids given regularly and repeatedly. Rolapitant is a long-acting NK-1 receptor antagonist with proven efficacy in controlling CINV as part of the prophylaxis regimen. This review will detail the clinical efficacy and safety of rolapitant in the treatment of patients with cancer receiving highly or moderately emetogenic chemotherapy.

Drug interactions with aprepitant or fosaprepitant: Review of literature and implications for clinical practice

Purpose Aprepitant and its parenteral formulation fosaprepitant are widely used for the prevention of chemotherapy-induced nausea and vomiting. Aprepitant exerts modest inhibitory effect on CYP3A4 and modest inductive effect on CYP2C9 substrates such as some antineoplastics and multiple other medications. This article is aimed to provide pharmacists and other healthcare professionals with an updated summary of drug-drug interactions of aprepitant/fosaprepitant and implications for clinical practice. Method We reviewed publications reporting drug-drug interactions between aprepitant/fosaprepitant and other medications. Results Coadministration of aprepitant with antineoplastics or opiods may result in significant elevations in the serum levels of the agents metabolized via CYP3A4, with the best documentation for cyclophosphamide, ifosfamide, erlotinib and oxycodone. These alterations did not translate into adverse outcomes and/or necessitate dosing adjustments. The levels of warfarin were significantly decreased by aprepitant requiring prolonged monitoring after discontinuation of aprepitant. Among direct oral anticoagulants, a theoretical interaction between aprepitant and rivaroxaban or apixaban exists. Interactions between aprepitant and quetiapine or diltiazem or sirolimus required dose reductions to avoid adverse outcomes. The intravenous route had a weaker inhibitory effect on CYP3A4 than the oral pathway. Conclusion The evidence on drug interactions of aprepitant with other medications is limited, and the impact on therapeutic outcomes remains to be determined. The intravenous regimen may be a preferred option. As utilization of aprepitant is expanding, practitioners and patients need to be educated about the potential for drug interactions and a need for careful monitoring of patients concurrently receiving aprepitant and CYP2C9 or CYP3A4 substrates, especially those with a narrow therapeutic window.

Aprepitant loaded solid preconcentrated microemulsion for enhanced bioavailability: A comparison with micronized Aprepitant

Aprepitant (APT) is a lipophilic, poorly water soluble drug with moderate permeability characteristic. Therefore, we aimed to improve solubility as well as permeability that could possibly improve oral bioavailability of APT. For this purpose, Quality by design (QbD) approach employing simplex lattice mixture design was used to prepare solid preconcentrated microemulsion (S-PCM). Further, the software generated numerically optimized S-PCM formulations were developed by utilizing desirability function. The spectral attributes (powder X-ray diffraction, ATR-FTIR, and differential scanning calorimetry) of S-PCM formulations suggested that APT was present in amorphous form. The results of droplet size (150-180 nm), zeta potential (-13 to -15 mV), poly dispersity index (PDI) (0.211-0.238) and emulsification time (<1 min), of these S-PCM formulations (SP1, SP2 and SP3) suggested spherical shape morphology (Transmission electron microscopy) with thermodynamic stability. The comparison of in vitro/ex vivo behavior of S-PCM (SP1) with micronized and non-micronized formulations of APT suggested 2-fold and 5-fold enhancement in solubility and permeability, respectively. This was further evident from pharmacokinetic studies in rabbits that showed 1.5-fold enhancement in bioavailability of S-PCM with respect to micronized APT. Thus, it could be envisaged that development of S-PCM formulation of APT is the best alternative to micronization technology based APT formulations reported earlier.

Pharmacokinetic and pharmacodynamic drug interactions with ethanol (alcohol)

Ethanol (alcohol) is one of the most widely used legal drugs in the world. Ethanol is metabolized by alcohol dehydrogenase (ADH) and the cytochrome P450 (CYP) 2E1 drug-metabolizing enzyme that is also responsible for the biotransformation of xenobiotics and fatty acids. Drugs that inhibit ADH or CYP2E1 are the most likely theoretical compounds that would lead to a clinically significant pharmacokinetic interaction with ethanol, which include only a limited number of drugs. Acute ethanol primarily alters the pharmacokinetics of other drugs by changing the rate and extent of absorption, with more limited effects on clearance. Both acute and chronic ethanol use can cause transient changes to many physiologic responses in different organ systems such as hypotension and impairment of motor and cognitive functions, resulting in both pharmacokinetic and pharmacodynamic interactions. Evaluating drug interactions with long-term use of ethanol is uniquely challenging. Specifically, it is difficult to distinguish between the effects of long-term ethanol use on liver pathology and chronic malnutrition. Ethanol-induced liver disease results in decreased activity of hepatic metabolic enzymes and changes in protein binding. Clinical studies that include patients with chronic alcohol use may be evaluating the effects of mild cirrhosis on liver metabolism, and not just ethanol itself. The definition of chronic alcohol use is very inconsistent, which greatly affects the quality of the data and clinical application of the results. Our study of the literature has shown that a significantly higher volume of clinical studies have focused on the pharmacokinetic interactions of ethanol and other drugs. The data on pharmacodynamic interactions are more limited and future research addressing pharmacodynamic interactions with ethanol, especially regarding the non-central nervous system effects, is much needed.

In vitro glucuronidation of aprepitant: a moderate inhibitor of UGT2B7

1. Aprepitant, an oral antiemetic, commonly used in the prevention of chemotherapy-induced nausea and vomiting, is primarily metabolized by CYP3A4. Aprepitant glucuronidation has yet to be evaluated in humans. The contribution of human UDP-glucuronosyltransferase (UGT) isoforms to the metabolism of aprepitant was investigated by performing kinetic studies, inhibition studies and correlation analyses. In addition, aprepitant was evaluated as an inhibitor of UGTs. 2. Glucuronidation of aprepitant was catalyzed by UGT1A4 (82%), UGT1A3 (12%) and UGT1A8 (6%) and Kms were 161.6 ± 15.6, 69.4 ± 1.9 and 197.1 ± 28.2 µM, respectively. Aprepitant glucuronidation was significantly correlated with both UGT1A4 substrates anastrazole and imipramine (rs = 0.77, p < 0.0001 for both substrates; n = 44), and with the UGT1A3 substrate thyroxine (rs = 0.58, p < 0.0001; n = 44). 3. We found aprepitant to be a moderate inhibitor of UGT2B7 with a Ki of ∼10 µM for 4-MU, morphine and zidovudine. Our results suggest that aprepitant can alter clearance of drugs primarily eliminated by UGT2B7. Given the likelihood for first-pass metabolism by intestinal UGT2B7, this is of particular concern for oral aprepitant co-administered with oral substrates of UGT2B7, such as zidovudine and morphine.

Use of a Physiologically Based Pharmacokinetic Model for Quantitative Prediction of Drug-Drug Interactions via CYP3A4 and Estimation of the Intestinal Availability of CYP3A4 Substrates

The purpose of this study was to predict the drug-drug interactions (DDIs) via CYP3A4 by estimating the extent of hepatic CYP3A4 inhibition based on a physiologically based pharmacokinetic (PBPK) model of both substrate and inhibitor and the increase in the intestinal availability (Fg ) due to the enzyme inhibition. For the DDIs resulting from reversible inhibition of CYP3A4, the prediction using in vivo Ki values estimated from other clinical DDI studies and predicted in vivo Ki values calculated using the correlation between the log P and the in vivo Ki /in vitro Ki ratio was more accurate than that using in vitro Ki values. Incorporating inhibition of both intestinal and hepatic metabolism resulted in better prediction than that obtained considering inhibition in the liver alone, and all the DDIs (AUC increase by the inhibitor) were predicted within 2-fold accuracy when in vivo Ki values were used. In addition, Fg values were successfully back-calculated from the clinical DDI data based on the present model. In conclusion, the present PBPK model incorporating the in vivo Ki values was found to be useful for quantitative prediction of clinical DDIs and for estimation of the Fg values for CYP3A4 substrates for which intravenous data were not available.

Drug-drug interaction profile of components of a fixed combination of netupitant and palonosetron: Review of clinical data

Neurokinin-1 (NK₁) receptor antagonists (RAs) are commonly coadministered with serotonin (5-HT₃) RAs (e.g. palonosetron (PALO)) to prevent chemotherapy-induced nausea/vomiting. Netupitant/palonosetron (NEPA), an oral fixed combination of netupitant (NETU)—a new NK₁ RA—and PALO, is currently under development. In vitro data suggest that NETU inhibits CYP3A4 and is a substrate for and weak inhibitor of P-glycoprotein (P-gp). This review evaluates potential drug–drug interactions between NETU or NEPA and CYP3A4 substrates/inducers/inhibitors or P-gp substrates in healthy subjects. Pharmacokinetic (PK) parameters were evaluated for each drug when NETU was coadministered with PALO (single doses) and when single doses of NETU or NEPA were coadministered with CYP3A4 substrates (erythromycin (ERY), midazolam (MID), dexamethasone (DEX), or oral contraceptives), inhibitors (ketoconazole (KETO)), or inducers (rifampicin (RIF)), or a P-gp substrate (digoxin (DIG)). Results showed no relevant PK interactions between NETU and PALO. Coadministration of NETU increased MID and ERY exposure and significantly increased DEX exposure in a dose-dependent manner; NETU exposure was unaffected. NEPA coadministration had no clinically significant effect on oral contraception, although levonorgestrel exposure increased. NETU exposure increased after coadministration of NEPA with KETO and decreased after coadministration with RIF; PALO exposure was unaffected. NETU coadministration did not influence DIG exposure. In conclusion, there were no clinically relevant interactions between NETU and PALO, or NEPA and oral contraceptives (based on levonorgestrel and ethinylestradiol exposure). Coadministration of NETU or NEPA with CYP3A4 inducers/inhibitors/substrates should be done with caution. Dose reduction is recommended for DEX. Dose adjustments are not needed for NETU coadministration with P-gp substrates.

The correlation between plasma aprepitant concentration and antiemetic effect in Japanese gastric or esophageal cancer patients

BACKGROUND

Chemotherapy-induced nausea and vomiting (CINV) are significant problems in cancer patients, but a correlation between plasma aprepitant concentration and antiemetic effect has not been reported. This study aimed to characterize the correlation between plasma aprepitant concentration and clinical antiemetic effect in a limited group of Japanese gastric or esophageal cancer patients.

METHODS

Thirty-three Japanese cancer patients receiving cisplatin-based chemotherapy for the first time following oral aprepitant (125 mg on day 1 and 80 mg on days 2 and 3) were enrolled. The plasma aprepitant concentrations 48 h after the first administration were determined using liquid chromatography-mass spectrometry. Patients were allocated to the high-concentration group (plasma aprepitant concentration was >331.1 ng/ml) or the low-concentration group (plasma aprepitant concentration was ≤ 331.1 ng/ml) to investigate the relationship between plasma aprepitant concentration and antiemetic effects.

RESULTS

No significant differences were found between the two groups in terms of percentage of CINV prevention. Of 13 patients who experienced CINV [MASCC Antiemesis Tool (MAT) score >3], those in the high-concentration group showed a significant improvement in CINV following aprepitant administration (days 1-3).

CONCLUSION

The present study suggests that the antiemetic effect of aprepitant is associated with plasma aprepitant concentration. A plasma aprepitant concentration of 331.1 ng/ml may be a valid threshold for identifying its optimal antiemetic effects in Japanese gastric or esophageal cancer patients.

Effects of aprepitant on the pharmacokinetics of controlled-release oral oxycodone in cancer patients

Purpose

Oxycodone is a µ-opioid receptor agonist widely used in the treatment of cancer pain. The predominant metabolic pathway of oxycodone is CYP3A4-mediated N-demethylation to noroxycodone, while a minor proportion undergoes 3-O-demethylation to oxymorphone by CYP2D6. The aim of this study was to investigate the effects of the mild CYP3A4 inhibitor aprepitant on the pharmacokinetics of orally administered controlled-release (CR) oxycodone.

Method

This study design was an open-label, single-sequence with two phases in cancer patients with pain who continued to be administered orally with multiple doses of CR oxycodone every 8 or 12 hours. Plasma concentration of oxycodone and its metabolites were measured up to 8 hours after administration as follows: on day 1, CR oxycodone was administered alone; on day 2, CR oxycodone was administered with aprepitant (125 mg, at the same time of oxycodone dosing in the morning). The steady-state trough concentrations (Css) were measured from day 1 to day 3.

Results

Aprepitant increased the area under the plasma concentration-time curve (AUC_0–8) of oxycodone by 25% (p<0.001) and of oxymorphone by 34% (p<0.001), as well as decreased the AUC_0–8 of noroxycodone by 14% (p<0.001). Moreover, aprepitant increased Css of oxycodone by 57% (p = 0.001) and of oxymorphone by 36% (p<0.001) and decreased Css of noroxycodone by 24% (p = 0.02) at day 3 compared to day 1.

Conclusions

The clinical use of aprepitant in patients receiving multiple doses of CR oxycodone for cancer pain significantly altered plasma concentration levels, but would not appear to need modification of the CR oxycodone dose.

Trial Registration

UMIN.ac.jp UMIN000003580.

Aprepitant reduces chemotherapy-induced vomiting in children and young adults with brain tumors

PURPOSE

Chemotherapy-induced nausea and vomiting are common and distressing side effects in patients with brain tumors and may be associated with radiation and the administration of highly emetogenic chemotherapy (HEC). Pediatric antiemetic guidelines recommend administration of a 5-hydroxytryptamine-3 (5HT3) receptor antagonists and the addition of aprepitant, a neurokinin 1 (NK1) antagonist with corticosteroids for the treatment of HEC. However, challenges persist in treating chemotherapy-induced nausea and vomiting in patients with brain tumors as corticosteroids are contraindicated due to potential impairment of the blood-brain barrier permeability. The objective was to determine whether a 5HT3 receptor antagonist and the addition of aprepitant, an NK1 antagonist without a corticosteroid, were effective in reducing HEC vomiting in pediatric brain tumor patients.

METHOD

A retrospective review found that 18 patients with a history of high-grade vomiting during radiation were prescribed a 5HT3 receptor antagonist and aprepitant without a corticosteroid during their first course of HEC. To determine the efficacy of aprepitant without a corticosteroid, each recipient was matched with 2 controls who did not receiv aprepitant.

RESULTS

During HEC, controls without aprepitant were more likely to have Grade 2 or higher vomiting than the aprepitant recipients (P = .03; odds ratio = 4.15; 95% confidence interval = 1.59-10.82), after controlling for radiation-associated vomiting toxicity.

DISCUSSION

Significantly less vomiting was identified in children receiving HEC and prescribed a 5HT3 receptor antagonist and aprepitant. Findings suggest that the addition of an NK1 antagonist may be beneficial to emetic control in this highly vulnerable population.

Aprepitant for the prevention of nausea and vomiting associated with chemotherapy and postoperative recovery

Chemotherapy-induced nausea and vomiting (CINV) and postoperative nausea and vomiting (PONV) can negatively impact patient quality of life, functional performance and activities of daily living. Although the development of serotonin receptor antagonists has greatly improved the control of acute emesis, delayed CINV remains a significant clinical issue. Aprepitant (Emend(®)) is the first commercially available drug from a new class of agents, the neurokinin-1 receptor antagonists. Elucidation of its mechanism of action has produced a greater understanding of the pathophysiology of nausea and vomiting. Oral aprepitant, in combination with a selective serotonin (5-HT3) receptor antagonist and corticosteroids, is indicated for the prevention of acute and delayed nausea and vomiting associated with highly and moderately emetogenic chemotherapy in adults. Aprepitant alone or in combination only with dexamethasone does not optimally control acute emesis compared with triple combination therapy. By contrast, aprepitant as monotherapy is indicated for the prevention of PONV. Aprepitant represents an emerging class of agents and its addition to standard therapy provides an advanced benefit in the prevention and treatment of CINV and PONV. Investigations of aprepitant for other indications are ongoing.