Elinzanetant, a new combined neurokinin-1/-3 receptor antagonist for the treatment of postmenopausal vasomotor symptoms.

INTRODUCTION: In many postmenopausal women, quality of life is decreased due to vasomotor symptoms. Efficient and well-tolerated non-hormonal treatment options are needed. AREAS COVERED: The present review summarizes what is known about the etiology of postmenopausal vasomotor symptoms as a rationale for the mechanism of action of Elinzanetant, a new neurokinin (NK)-1/-3 receptor antagonist, as well as its efficacy and side effect profile. EXPERT OPINION: Elinzanetant likely exerts an antagonistic effect on the NK-3 receptor in the preoptic thermoregulatory zone, but also an additional antagonistic effect on the NK-1 receptor possibly leading to a reduction in vasodilatation and heat-sensing neuro-activity. Elinzanetant's reported peak drug concentrations are reached within one hour and the terminal elimination half-life is approximately 15 hours. Two phase IIb clinical trials evaluated the safety profile and efficacy of several doses. There were no serious adverse events, which also included a lack of evidence of drug-related hepatotoxicity. Overall, Elinzanetant seems to be well-tolerated. In the SWITCH-1 study, the 120 mg/day and 160 mg/day regimen showed good efficacy for the treatment of vasomotor symptoms and led to significant improvements in quality of life. Thus, 120 mg oral Elinzanetant/day was used in phase III trials, whose results have not yet been published.

A phase 1 pharmacokinetic study of oral NEPA, the fixed combination of netupitant and palonosetron, in Chinese healthy volunteers.

PURPOSE: Oral NEPA, the only fixed-combination antiemetic, is composed of the neurokinin-1 receptor antagonist netupitant (300 mg) and the 5-hydroxytryptamine-3 receptor antagonist palonosetron (0.50 mg). This study was conducted to evaluate the pharmacokinetic profile of netupitant and its main metabolites M1 and M3, and palonosetron in Chinese subjects. Oral NEPA tolerability and safety were also analyzed. METHODS: This was a single-center, single-dose phase 1 study in healthy, adult Chinese volunteers. Eligible subjects received oral NEPA, and blood samples were collected on day 1 predose and at various time points up until day 10 postdose. Pharmacokinetic parameters were analyzed using noncompartmental methods. For safety assessments, adverse events (AEs) were monitored during the study. RESULTS: In total 18 Chinese healthy volunteers received oral NEPA. Netupitant mean maximum plasma concentration (Cmax) [± standard deviation] of 698 ± 217 ng/mL was reached at 3-6 h, with a mean total exposure (AUC0-inf) of 22,000 ± 4410 h·ng/mL. For palonosetron, a mean Cmax of 1.8 ± 0.252 ng/mL was reached at 2-6 h postadministration, with a mean AUC0-inf of 81.0 ± 14.0 h·ng/mL. The most common treatment-related AEs in > 2 subjects were constipation (n = 9) and tiredness (n = 3). No severe AEs were observed, and no subject withdrew due to AEs. CONCLUSION: Following single-dose administration of oral NEPA in Chinese subjects, the pharmacokinetic profiles of the NEPA components were mostly similar to those reported previously in Caucasians. NEPA was well tolerated with a safety profile in line with that observed in pivotal trials in Caucasians.

Extrapolation of Adult Efficacy to Pediatric Patients With Chemotherapy-Induced Nausea and Vomiting.

Chemotherapy-induced nausea and vomiting (CINV) is a common treatment-related adverse event that negatively impacts the quality of life of cancer patients. During pediatric drug development, extrapolation of efficacy from adult to pediatric populations is a pathway that can minimize the exposure of children to unnecessary clinical trials, improve efficiency, and increase the likelihood of success in obtaining a pediatric indication. The acceptability of the use of extrapolation depends on a series of evidence-based assumptions regarding the similarity of disease, response to intervention, and exposure-response relationships between adult and pediatric patients. This study evaluated publicly available summaries of data submitted to the US Food and Drug Administration for drugs approved for CINV to assess the feasibility of extrapolation for future development programs. Extracted data included trial design, emetogenic potential of chemotherapy, primary end points, participant enrollment criteria, and antiemetic pharmacokinetics. Adult and pediatric clinical trial designs for assessment of efficacy and safety shared key design elements. Antiemetic drugs found to be efficacious in adults were also efficacious in pediatric patients. Systemic drug concentrations at approved doses were similar for ondansetron, granisetron, and aprepitant, but an exposure-response analysis of palonosetron in children suggested that higher palonosetron systemic exposure is necessary for the prevention of CINV in the pediatric population. For 5-hydroxytryptamine-3 and neurokinin-1 receptor antagonist antiemetic drugs, efficacy in adults predicts efficacy in children, supporting the extrapolation of effectiveness of an antiemetic product in children from adequate and well-controlled studies in adult patients with CINV.

A pH-responsive nanoparticle targets the neurokinin 1 receptor in endosomes to prevent chronic pain.

Nanoparticle-mediated drug delivery is especially useful for targets within endosomes because of the endosomal transport mechanisms of many nanomedicines within cells. Here, we report the design of a pH-responsive, soft polymeric nanoparticle for the targeting of acidified endosomes to precisely inhibit endosomal signalling events leading to chronic pain. In chronic pain, the substance P (SP) neurokinin 1 receptor (NK1R) redistributes from the plasma membrane to acidified endosomes, where it signals to maintain pain. Therefore, the NK1R in endosomes provides an important target for pain relief. The pH-responsive nanoparticles enter cells by clathrin- and dynamin-dependent endocytosis and accumulate in NK1R-containing endosomes. Following intrathecal injection into rodents, the nanoparticles, containing the FDA-approved NK1R antagonist aprepitant, inhibit SP-induced activation of spinal neurons and thus prevent pain transmission. Treatment with the nanoparticles leads to complete and persistent relief from nociceptive, inflammatory and neuropathic nociception and offers a much-needed non-opioid treatment option for chronic pain.

The safety of rolapitant for the treatment of nausea and vomiting associated with chemotherapy.

Introduction: Chemotherapy-induced nausea and vomiting is a significant clinical issue that affects patients' quality of life as well as treatment decisions. Significant improvements in the control of chemotherapy-induced nausea and vomiting have occurred in the past 15 years with the introduction of new antiemetic agents 5-HT3, receptor antagonists, neurokinin-1 receptor antagonists, and olanzapine. Oral (aprepitant, 2003; netupitant, 2014; rolapitant, 2015) neurokinin-1 receptor antagonists have been developed along with intravenous formulations (fosaprepitant, NEPA, rolapitant, HTX-019) for the prevention of chemotherapy-induced nausea and vomiting.Areas covered: This review presents a description of the safety and efficacy of rolapitant along with a comparison to the other oral and intravenous formulations of the neurokinin-1 receptor antagonists.Expert opinion: Oral rolapitant has been demonstrated in clinical trials to be safe and effective in controlling chemotherapy-induced nausea and vomiting in patients receiving moderately and highly emetogenic chemotherapy. Rolapitant has a longer half-life (180 h) than other commercially available NK-1 receptor antagonists and does not induce or inhibit CYP34A, unlike the other NK-1 receptor antagonists. Future studies may determine if these may be important clinical issues.

Pharmacokinetics of maropitant citrate in New Zealand White rabbits (Oryctolagus cuniculus).

OBJECTIVE: To determine the pharmacokinetics and adverse effects of maropitant citrate after IV and SC administration to New Zealand White rabbits (Oryctolagus cuniculus). ANIMALS: 11 sexually intact (3 males and 8 females) adult rabbits. PROCEDURES: Each rabbit received maropitant citrate (1 mg/kg) IV or SC. Blood samples were collected at 9 (SC) or 10 (IV) time points over 48 hours. After a 2-week washout period, rabbits received maropitant by the alternate administration route. Pharmacokinetic parameters were calculated. Body weight, food and water consumption, injection site, mentation, and urine and fecal output were monitored. RESULTS: Mean ± SD maximum concentration after SC administration was 14.4 ± 10.9 ng/mL and was detected at 1.25 ± 0.89 hours. Terminal half-life after IV and SC administration was 10.4 ± 1.6 hours and 13.1 ± 2.44 hours, respectively. Bioavailability after SC administration was 58.9 ± 13.3%. Plasma concentration at 24 hours was 2.87 ± 1.69 ng/mL after IV administration and 3.4 ± 1.2 ng/mL after SC administration. Four rabbits developed local dermal reactions at the injection site after SC injection. Increased fecal production was detected on the day of treatment and 1 day after treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Plasma concentrations of rabbits 24 hours after SC and IV administration of maropitant citrate (1 mg/kg) were similar to those of dogs at 24 hours. Reactions at the SC injection site were the most common adverse effect detected. Increased fecal output may suggest an effect on gastrointestinal motility. Additional pharmacodynamic and multidose studies are needed.

Timing flexibility of oral NEPA, netupitant-palonosetron combination, administration for the prevention of chemotherapy-induced nausea and vomiting (CINV).

PURPOSE: The administration timing of antiemetic and chemotherapeutic regimens is often determined by regulatory indications, based on registration studies. Oral NEPA, fixed combination of the neurokinin-1 receptor antagonist (NK1RA) netupitant and the 5-hydroxytryptamine-3 RA (5-HT3RA) palonosetron, is recommended to be administered approximately 60 min before chemotherapy. Reducing chair time for chemotherapy administration at oncology day therapy units would improve facility efficiency without compromising patient symptom management. The objective was to determine if oral NEPA can be administered closer to chemotherapy initiation without compromising patient symptom management. METHODS: NK1 receptor occupancy (NK1RO) time course in the brain was determined using positron emission tomography; netupitant and palonosetron plasma concentration-time profiles were described by pharmacokinetic (PK) models; and the rate, extent, and duration of RO by netupitant and palonosetron were predicted by pharmacodynamic modeling. Clinical efficacy data from a pivotal study in cisplatin and oral NEPA-receiving patients were reviewed in the context of symptom management. RESULTS: Striatal 90% NK1RO, assumed to correlate with NK1RA antiemetic efficacy, was predicted at netupitant plasma concentration of 225 ng/mL, reached at 2.23 h following NEPA administration. Palonosetron 90% 5-HT3RO was predicted at a 188-ng/L plasma concentration, reached at 1.05 h postdose. The mean time to first treatment failure for the 1.5% of NEPA-treated patients without complete response receiving highly emetogenic chemotherapy was 8 h. Antiemetic efficacy was sustained over 5 days despite the expected decrease of NK1RO and 5-HT3RO. CONCLUSIONS: Results suggest that administering oral NEPA closer to initiation of cisplatin administration would provide similar antiemetic efficacy. Prospective clinical validation is required.

HTX-019 via 2-min injection or 30-min infusion in healthy subjects.

AIM: HTX-019 (CINVANTI® [aprepitant injectable emulsion]) is a neurokinin 1 receptor antagonist approved for preventing acute and delayed chemotherapy-induced nausea and vomiting (CINV). HTX-019 is free of polysorbate 80 and other synthetic surfactants and showed bioequivalence to and a more favorable safety profile than fosaprepitant when administered as a 30-min infusion in healthy subjects. The shortage of small-volume parenteral solutions led to a recommendation to administer HTX-019 by intravenous push. The objectives were to evaluate pharmacokinetics, tolerability and safety following HTX-019 administration by injection versus infusion. MATERIALS & METHODS: Study comprised Part A, a pilot Phase I, single-center, randomized, pharmacokinetic, safety and tolerability, open-label study, followed by Part B, a two-sequence crossover study of HTX-019 130 mg in healthy adults, via injection and infusion. Blood samples were evaluated for aprepitant pharmacokinetics and bioequivalence. Safety evaluations included treatment-emergent adverse events (TEAEs), vital signs, clinical laboratory testing and electrocardiograms. RESULTS: In Part A, 24 subjects were randomly assigned to three cohorts (n = 8 per cohort) and received HTX-019 130 mg, administered intravenously over 15 min (cohort 1), 5 min (cohort 2) or 2 min (cohort 3). Progression to Part B occurred after acceptable tolerability was established in cohorts 2 and 3. In Part B, 50 randomized subjects received a 2-min injection (9 ml/min) and 30-min infusion (296 ml/h) of HTX-019 130 mg. Bioequivalence was demonstrated for HTX-019 injection and infusion. Both administration methods via a peripheral line were well tolerated; eight subjects experienced 11 TEAEs (six related) following injection and nine experienced 14 TEAEs (nine related) following infusion. Headache and fatigue were the most prevalent treatment-related TEAEs; one subject per group experienced feeling hot ≤30 min after drug administration. CONCLUSION: Pharmacokinetic and tolerability profiles of 2-min HTX-019 injection support this potential alternative administration method for CINV prevention.

Pharmacokinetic Interactions of Rolapitant With Cytochrome P450 3A Substrates in Healthy Subjects.

Rolapitant (Varubi) is a neurokinin-1 receptor antagonist approved for the prevention of chemotherapy-induced nausea and vomiting. Rolapitant is primarily metabolized by the cytochrome P450 3A4 (CYP3A4) enzyme. Unlike other neurokinin-1 receptor antagonists, rolapitant is neither an inhibitor nor an inducer of CYP3A4 in vitro. The objective of this analysis was to examine the pharmacokinetics of rolapitant in healthy subjects and assess drug-drug interactions between rolapitant and midazolam (a CYP3A substrate), ketoconazole (a CYP3A inhibitor), or rifampin (a CYP3A4 inducer). Three phase 1, open-label, drug-drug interaction studies were conducted to examine the pharmacokinetic interactions of orally administered rolapitant with midazolam, rolapitant with ketoconazole, and rolapitant with rifampin. The pharmacokinetic profiles of midazolam and 1-hydroxy midazolam metabolites were essentially unchanged when coadministered with rolapitant, indicating the lack of a clinically relevant inhibition or induction of CYP3A by rolapitant. Coadministration of ketoconazole with rolapitant had no effects on rolapitant maximum concentration and resulted in an approximately 20% increase in the area under the concentration-time curve of rolapitant, suggesting that strong CYP3A inhibitors have minimal inhibitory effects on rolapitant exposure. Repeated administrations of rifampin appeared to reduce rolapitant exposure, resulting in a 33% decrease in maximum concentration and 87% decrease in area under the concentration-time curve from time zero to infinity. Coadministration of rolapitant did not affect the exposure of midazolam. Rifampin coadministration resulted in lower concentrations of rolapitant, and ketoconazole coadministration had no or minimal effects on rolapitant exposure. Rolapitant was safe and well tolerated when coadministered with ketoconazole, rifampin, or midazolam. No new safety signals were reported compared with previous studies of rolapitant.

Complementary Pharmacokinetic Profiles of Netupitant and Palonosetron Support the Rationale for Their Oral Fixed Combination for the Prevention of Chemotherapy-Induced Nausea and Vomiting.

NEPA is the first fixed-combination antiemetic composed of the neurokinin-1 receptor antagonist netupitant (netupitant; 300 mg) and the 5-hydroxytryptamine-3 receptor antagonist palonosetron (palonosetron; 0.50 mg). This study evaluated the pharmacokinetic profiles of netupitant and palonosetron. The pharmacokinetic profiles of both drugs were summarized using data from phase 1-3 clinical trials. netupitant and palonosetron have high absolute bioavailability (63%-87% and 97%, respectively). Their overall systemic exposures and maximum plasma concentrations are similar under fed and fasting conditions. netupitant binds to plasma proteins in a high degree (>99%), whereas palonosetron binds to a low extent (62%). Both drugs have large volumes of distribution (cancer patients: 1656-2257 L and 483-679 L, respectively). netupitant is metabolized by cytochrome P450 3A4 to 3 major pharmacologically active metabolites (M1, M2, and M3). palonosetron is metabolized by cytochrome P450 2D6 to 2 major substantially inactive metabolites (M4 and M9). Both drugs have similar intermediate-to-low systemic clearances and long half-lives (cancer patients: netupitant, 19.5-20.8 L/h and 56.0-93.8 hours; palonosetron: 7.0-11.3 L/h and 43.8-65.7 hours, respectively). netupitant and its metabolites are eliminated via the hepatic/biliary route (87% of the administered dose), whereas palonosetron and its metabolites are mainly eliminated via the kidneys (85%-93%). Altogether, these data explain the lack of pharmacokinetic interactions between netupitant and palonosetron at absorption, binding, metabolic, or excretory level, thus highlighting their compatibility as the oral fixed combination NEPA, with administration convenience that may reduce dosing mistakes and increase treatment compliance.

Absorption, metabolism, and excretion of the antiemetic rolapitant, a selective neurokinin-1 receptor antagonist, in healthy male subjects.

Rolapitant is a neurokinin-1 receptor antagonist that is approved in combination with other antiemetic agents in adults for the prevention of delayed nausea and vomiting (CINV) associated with initial and repeat courses of emetogenic cancer chemotherapy, including but not limited to highly emetogenic chemotherapy. Here, we assessed the absorption, metabolism, and excretion of 14C-labeled rolapitant in healthy male subjects. Rolapitant was administered as a single 180-mg oral dose containing approximately 100 µCi of total radioactivity, with plasma, urine, and fecal samples collected at defined intervals after dosing. Rolapitant had a large apparent volume of distribution, indicating that it is widely distributed into body tissues. Rolapitant was slowly metabolized and eliminated with a mean half-life of 186 h. Exposure to the major metabolite of rolapitant, C4-pyrrolidinyl hydroxylated rolapitant or M19, was approximately 50% of rolapitant exposure in plasma. Renal clearance was not a significant elimination route for rolapitant-related entities. Total radioactivity recovered in urine accounted for 14.2% of the dose, compared to 72.7% recovery in feces. Adverse events (AEs) were generally mild; there were no serious AEs, and no clinically significant changes in laboratory or electrocardiogram parameters were observed. The combination of rolapitant safety, its long half-life, extensive tissue distribution, and slow elimination via the hepatobiliary route (rather than renal excretion) suggest suitability that a single dose of rolapitant may provide protection against CINV beyond the first 24 h after chemotherapy administration.

Drug-drug interactions with aprepitant in antiemetic prophylaxis for chemotherapy.

In the current guidelines to prevent hemotherapyinduced nausea and vomiting, multiple antiemetic drugs are administered simultaneously. In patients who receive highly emetogenic chemotherapy, aprepitant, an NK1-receptor antagonist, is combined with ondansetron and dexamethasone. Aprepitant can influence the pharmacokinetics of other drugs, as it is an inhibitor and inducer of CYP3A4. Some anticancer drugs and other co-medication frequently used in cancer patients are CYP3A4 or CYP29C substrates. We give an overview of the metabolism and current data on clinically relevant drug-drug interactions with aprepitant during chemotherapy. Physicians should be aware of the potential risk of drug-drug interactions with aprepitant, especially in regimens with curative intent. More research should be performed on drug-drug interactions with aprepitant and their clinical consequences to make evidence-based recommendations.

Bioequivalence of HTX-019 (aprepitant IV) and fosaprepitant in healthy subjects: a Phase I, open-label, randomized, two-way crossover evaluation.

INTRODUCTION: Fosaprepitant, an intravenous (IV) aprepitant prodrug for chemotherapy-induced nausea and vomiting prophylaxis, is associated with systemic and infusion-site reactions attributed in part to its surfactant, polysorbate 80. HTX-019 is an IV aprepitant formulation free of polysorbate 80 and other synthetic surfactants. MATERIALS AND METHODS: This open-label, single-dose, randomized, two-way crossover bioequivalence study compared pharmacokinetics and safety of HTX-019 and fosaprepitant. Healthy subjects received single-dose HTX-019 (130 mg) or fosaprepitant (150 mg) IV over 30 min, with ≥7-day washout between doses. Blood samples were evaluated for pharmacokinetics and bioequivalence; safety evaluation included treatment-emergent adverse events (TEAEs) and serious adverse events. Ninety-seven of one hundred enrolled subjects completed the study. RESULTS: Baseline characteristics were comparable between treatment sequences. For HTX-019, mean (percent coefficient of variation) area under the curve (AUC) from time 0 to time of last measurable plasma concentration (AUC0-t), AUC from time 0 to infinity (AUC0-inf), and plasma concentration at 12 h (C12 h) for HTX-019 were 43,729 h*ng/mL (32.7), 45,460 h*ng/mL (36.8), and 988.4 ng/mL (27.5), respectively; corresponding fosaprepitant values were 44,130 h*ng/mL (32.0), 46,163 h*ng/mL (36.6), and 1,022 ng/mL (28.5). Also, 90% CIs (94.186-101.354) were within bioequivalence bounds (80%-125%). Within 1 h following infusion start, one (1%) HTX-019 recipient reported one TEAE, while 20 (20%) fosaprepitant recipients reported 32 TEAEs. Dyspnea occurred in three fosaprepitant recipients (at <1 min in two subjects and at 18 min in one subject, considered study drug related) and one HTX-019 recipient (at 120 h, associated with a respiratory tract infection and considered not related to the study drug). No severe TEAEs, serious adverse events, or deaths occurred; all TEAEs resolved. CONCLUSION: HTX-019 was bioequivalent to fosaprepitant and may provide a safer alternative to fosaprepitant for chemotherapy-induced nausea and vomiting prophylaxis.

Pharmacokinetics of Rolapitant in Patients With Mild to Moderate Hepatic Impairment.

Rolapitant is a selective and long-acting neurokinin-1 receptor antagonist approved in an oral formulation in combination with other antiemetic agents for the prevention of delayed chemotherapy-induced nausea and vomiting in adults. This was a phase 1 open-label, parallel-group pharmacokinetic and safety study of a single oral dose of 180 mg of rolapitant and its major active metabolite, M19, in subjects with mild and moderate hepatic impairment compared with healthy matched controls. Pharmacokinetics were assessed by a mixed-model analysis of variance of log-transformed values for maximum observed plasma concentration (Cmax ), observed time at Cmax (tmax ), area under the plasma concentration-time curve (AUC) from time 0 to the time of the last quantifiable concentration (AUC0-t ), and AUC from time 0 to 120 hours (AUC0-120 ), with hepatic group as a fixed effect. Mean rolapitant Cmax , AUC0-t , and AUC0-120 were similar in the mild hepatic impairment and healthy control groups. In subjects with moderate hepatic impairment, AUC0-t was similar and Cmax was 25% lower than in healthy controls. Mean M19 Cmax and AUC0-t were similar in the mild hepatic impairment group and healthy controls, but <20% lower in those with moderate hepatic impairment versus healthy controls. Fraction of unbound rolapitant was comparable in all groups for rolapitant and M19. Rolapitant was well tolerated in all groups, without serious adverse events. Pharmacokinetic differences between healthy subjects and those with mild or moderate hepatic impairment are unlikely to pose a safety risk and do not warrant predefined dosage adjustment in the presence of hepatic impairment.

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.

Bioequivalence of Intravenous and Oral Rolapitant: Results From a Randomized, Open-Label Pivotal Study.

Rolapitant, a selective and long-acting neurokinin-1 receptor antagonist, is approved in an oral formulation for the prevention of delayed chemotherapy-induced nausea and vomiting in adults. The objective of this pivotal study was to assess the bioequivalence of a single intravenous infusion of rolapitant versus a single oral dose of rolapitant. In this randomized, open-label phase 1 study, healthy volunteers were administered rolapitant as a 180-mg oral dose or a 30-minute 166.5-mg intravenous infusion. Blood samples for pharmacokinetic analysis were collected predose and at points up to 912 hours postdose. Criteria for bioequivalence of the intravenous dose versus the oral dose were met if the 90% confidence intervals (CIs) for the ratios of the geometric least-squares means (GLSMs) for the area under the plasma concentration-time curve (AUC) from time 0 to the time of the last quantifiable concentration (AUC0-t ) and AUC from time 0 extrapolated to infinity (AUC0-∞ ) for rolapitant were within 0.80-1.25. Mean rolapitant systemic exposure and half-lives were similar in the oral (n = 62) and intravenous (n = 61) rolapitant groups. The 90%CIs of the ratio of GLSMs were within the 0.80-1.25 range for AUC0-t (0.94-1.09) and AUC0-∞ (0.93-1.10). The incidence of treatment-emergent adverse events, all mild or moderate in severity, was similar in the intravenous and oral groups. A 166.5-mg intravenous infusion of rolapitant met the bioequivalence criteria based on AUC to a 180-mg oral dose and was well tolerated.

Clinical pharmacology of neurokinin-1 receptor antagonists for the treatment of nausea and vomiting associated with chemotherapy.

INTRODUCTION: Five NK-1 RA formulations are commercially available to treat the delayed phase of chemotherapy-induced nausea and vomiting (CINV) occurring between days 2-5 post chemotherapy (aprepitant oral capsule and suspension, fosaprepitant intravenous infusion, netupitant/palonosetron capsules and rolapitant tablet) but no direct comparative studies have been conducted to determine their relative clinical utility. Areas covered: Information on pharmacology and safety of the NK-1 RAs derived from PubMed showed that all bind the NK-1 receptor with high affinity and selectivity. There is substantial variation in the disposition and time course in the body of NK-1 RAs because of the differential effects of hepatic metabolism. Unlike netupitant and rolapitant, aprepitant is metabolized extensively by cytochrome P450 (CYP) 3A4. Aprepitant and netupitant also both inhibit CYP3A4. Consequently, aprepitant not only has a much shorter elimination half-life than netupitant and rolapitant but also a more prolific drug interaction profile. All of the NK-1 RAs are efficacious and safe, and are suitable for use in a range of different patient populations, including those with mild or moderate hepatic or renal impairment. Expert opinion: While discovery of NK-1 RAs represents a major breakthrough in CINV control, further work is needed to improve control of chemotherapy-induced nausea.

Rolapitant Absolute Bioavailability and PET Imaging Studies in Healthy Adult Volunteers.

Rolapitant, a selective, long-acting neurokinin-1 (NK-1) receptor antagonist, demonstrated efficacy in preventing chemotherapy-induced nausea and vomiting (CINV) in patients receiving highly or moderately emetogenic chemotherapy. Two studies in healthy volunteers evaluated 1) absolute bioavailability and 2) NK-1 receptor occupancy of oral rolapitant. Absolute bioavailability, determined by the ratio of dose-normalized exposure following a 180-mg oral dose vs. an intravenous microdose, was ∼100%. Brain imaging by positron emission tomography 120 h after a single dose showed that NK-1 receptor occupancy increased with escalating doses (4.5-180 mg) but was not dose-proportional; a 180-mg dose resulted in near-saturable binding to NK-1 receptors (mean ± standard deviation: 94% ± 9%). A pharmacokinetic-pharmacodynamic model predicted that rolapitant plasma concentrations >348 ng/mL would result in >90% NK-1 receptor occupancy in the cortex up to 120 h postdose. These results support administration of a single 180-mg oral dose of rolapitant for CINV prevention.

Biaryls as potent, tunable dual neurokinin 1 receptor antagonists and serotonin transporter inhibitors.

Depression is a serious illness that affects millions of patients. Current treatments are associated with a number of undesirable side effects. Neurokinin 1 receptor (NK1R) antagonists have recently been shown to potentiate the antidepressant effects of serotonin-selective reuptake inhibitors (SSRIs) in a number of animal models. Herein we describe the optimization of a biaryl chemotype to provide a series of potent dual NK1R antagonists/serotonin transporter (SERT) inhibitors. Through the choice of appropriate substituents, the SERT/NK1R ratio could be tuned to afford a range of target selectivity profiles. This effort culminated in the identification of an analog that demonstrated oral bioavailability, favorable brain uptake, and efficacy in the gerbil foot tap model. Ex vivo occupancy studies with compound 58 demonstrated the ability to maintain NK1 receptor saturation (>88% occupancy) while titrating the desired level of SERT occupancy (11-84%) via dose selection.

5-HT3 receptors as important mediators of nausea and vomiting due to chemotherapy.

Chemotherapy-induced nausea and vomiting (CINV) is associated with a significant deterioration in quality of life. The emetogenicity of the chemotherapeutic agents, repeated chemotherapy cycles, and patient risk factors significantly influence CINV. The use of a combination of a 5-hydroxytryptamine-3 (5-HT3) receptor antagonist, dexamethasone, and a neurokinin-1 (NK-1) receptor antagonist has significantly improved the control of acute and delayed emesis in single-day chemotherapy. The first generation 5-HT3 receptor antagonists have been very effective in the control of chemotherapy induced emesis in the first 24 h postchemotherapy (acute emesis), but have not been as effective against delayed emesis (24-120 h postchemotherapy). Palonosetron, a second generation 5-HT3 receptor antagonist with a different half-life, a different binding capacity, and a different mechanism of action than the first generation 5-HT3 receptor antagonists appears to be the most effective agent in its class. Despite the control of emesis, nausea has not been well controlled by current agents. Olanzapine, a FDA approved antipsychotic that blocks multiple neurotransmitters: dopamine at D1, D2, D3, D4 brain receptors, serotonin at 5-HT2a, 5-HT2c, 5-HT3, 5-HT6 receptors, catecholamines at alpha1 adrenergic receptors, acetylcholine at muscarinic receptors, and histamine at H1 receptors, has emerged in recent trials as an effective preventative agent for chemotherapy-induced emesis and nausea, as well as a very effective agent for the treatment of breakthrough emesis and nausea. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.