Effect of netupitant, a highly selective NK1 receptor antagonist, on the pharmacokinetics of palonosetron and impact of the fixed dose combination of netupitant and palonosetron when coadministered with ketoconazole, rifampicin, and oral contraceptives

Challenges in the Development of Intravenous Neurokinin-1 Receptor Antagonists: Results of a Safety and Pharmacokinetics Dose-Finding, Phase 1 Study of Intravenous Fosnetupitant

Oral NEPA is the fixed-combination antiemetic comprising netupitant (neurokinin-1 receptor antagonist [NK₁ RA]) and palonosetron (5-hydroxytryptamine-3 receptor antagonist [5-HT₃ RA]). Intravenous (IV) NEPA, containing fosnetupitant, a water-soluble N-phosphoryloxymethyl prodrug of netupitant, has been developed. Fosnetupitant does not require excipients or solubility enhancers often used to increase IV NK₁ RA water solubility, preventing the occurrence of hypersensitivity and infusion-site reactions associated with these products. In this phase 1 study, subjects received a 30-minute placebo or fosnetupitant (17.6-353 mg) infusion and an oral NEPA or placebo capsule, with 2-sequence crossover treatment for fosnetupitant 118- to 353-mg dose cohorts. IV fosnetupitant safety and pharmacokinetics were evaluated, and its equivalence to an oral netupitant 300-mg dose was defined. Overall, 158 healthy volunteers were enrolled. All adverse events (AEs) were mild or moderate in intensity. Doppler-identified infusion-site asymptomatic thrombosis occurred in 5.4% (fosnetupitant) and 1.2% (oral NEPA) of subjects. The frequency or number of treatment-related AEs did not increase with ascending fosnetupitant doses. The most common treatment-related AEs were headache (fosnetupitant, 8.1%; oral NEPA, 12.7%) and constipation (fosnetupitant, 1.4%; oral NEPA, 7.5%). A fosnetupitant 235-mg dose was equivalent, in terms of netupitant exposure, to 300-mg oral netupitant. The safety profile of a single fosnetupitant 235-mg infusion was similar to that of single-dose oral NEPA.

Netupitant/Palonosetron: A Review in Chemotherapy-Induced Nausea and Vomiting

Netupitant/palonosetron (NEPA; Akynzeo^®), available in oral and intravenous (IV) formulations, is a fixed-dose combination of the neurokinin 1 (NK1) receptor antagonist netupitant (or the prodrug, fosnetupitant, in the IV formulation) and the second-generation serotonin 3 (5-HT₃) receptor antagonist palonosetron. Administered as a single dose, (fos)netupitant/palonosetron (in combination with dexamethasone) is indicated for the prevention of acute and delayed chemotherapy-induced nausea and vomiting (CINV) in adults. In clinical trials, (fos)netupitant/palonosetron plus dexamethasone was associated with high complete response rates (no emesis and no rescue medication) in the acute, delayed and overall phases in patients receiving highly or moderately emetogenic chemotherapy, with efficacy maintained over multiple cycles. Further, oral netupitant/palonosetron was found to be superior to palonosetron and non-inferior to aprepitant plus granisetron in preventing CINV in individual trials. Both the oral and IV formulations of the drug combination are well tolerated. The fixed-dose combination is concordant with guideline recommendations and provides a simple and convenient option for prophylaxis against acute and delayed CINV in patients receiving highly or moderately emetogenic chemotherapy.

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 (C_max) [± standard deviation] of 698 ± 217 ng/mL was reached at 3-6 h, with a mean total exposure (AUC_0-inf) of 22,000 ± 4410 h·ng/mL. For palonosetron, a mean C_max of 1.8 ± 0.252 ng/mL was reached at 2-6 h postadministration, with a mean AUC_0-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.

Drug-Drug Interaction Studies With Oral Contraceptives: Pharmacokinetic/Pharmacodynamic and Study Design Considerations

Oral contraceptives (OCs) are the most widely used form of birth control among women of childbearing potential. Knowledge of potential drug-drug interactions (DDIs) with OCs becomes imperative to provide information on the medication to women of childbearing potential and enable their inclusion in clinical trials, especially if the new molecular entity is a teratogen. Although a number of DDI guidance documents are available, they do not provide recommendations for the design and conduct of OC DDI studies. The evaluation of DDI potential of a new molecular entity and OCs is particularly challenging because of the availability of a wide variety of combinations of hormonal contraceptives, different doses of the ethinyl estradiol, and different metabolic profiles of the progestin component. The aim of this review is to comprehensively discuss factors to be considered such as pharmacokinetics (PK), pharmacodynamics (PD), choice of OC, and study population for the conduct of in vivo OC DDI studies. In this context, metabolic pathways of OCs, the effect of enzyme inhibitors and inducers, the role of sex hormone-binding globulin in the PK of progestins, current evidence on OC DDIs, and the interpretation of PD end points are reviewed. With the emergence of new tools like physiologically based PK modeling, the decision to conduct an in vivo study can be made with much more confidence. This review provides a comprehensive overview of various factors that need to be considered in designing OC DDI studies and recommends PK-based DDI studies with PK end points as adequate measures to establish clinical drug interaction and measurement of PD end points when there is basis for PD interaction.

Pharmacokinetic profile and safety of intravenous NEPA, a fixed combination of fosnetupitant and palonosetron, in cancer patients: Prevention of chemotherapy-induced nausea and vomiting associated with highly emetogenic chemotherapy

NEPA is the fixed combination antiemetic composed of the neurokinin-1 receptor antagonist netupitant and the 5-hydroxytryptamine-3 receptor antagonist palonosetron. The intravenous (i.v.) formulation of NEPA (fosnetupitant 235 mg/palonosetron 0.25 mg) was developed to enhance the convenience of NEPA administration. In a phase 3 study, i.v. NEPA showed acceptable safety with low risk for injection-site reactions. This study evaluated the pharmacokinetics and safety of i.v. NEPA in cancer patients. This was a single-center, single-dose phase 1 study in patients receiving highly emetogenic chemotherapy. Patients received a 30-min infusion of i.v. NEPA plus oral dexamethasone (12 mg) prior to chemotherapy, and oral dexamethasone (8 mg/daily) on days 2-4. Twenty-four patients received the complete i.v. NEPA infusion volume. Fosnetupitant maximum plasma concentration (C_max) was reached at the end of infusion and decreased to <1% of C_max 30 min later. Netupitant was rapidly released from its prodrug and C_max of 590 ng/ml was reached at the end of fosnetupitant infusion, with a mean exposure (AUC_∞) of 15,588 h∙ng/ml. Palonosetron C_max was reached at the end of infusion, with a mean AUC_∞ of 36.07 h∙ng/ml. The most common adverse events were constipation (29%), nausea (17%), and vasospasm (8%). No i.v. NEPA-related injection site reactions occurred. Fosnetupitant conversion to netupitant occurred rapidly in cancer patients. Netupitant and palonosetron pharmacokinetic profiles in i.v. NEPA were similar to those reported for oral NEPA. i.v. NEPA was well tolerated with a similar safety profile to oral NEPA. i.v. NEPA provides additional administration convenience. Clinical trial registration number: EudraCT 2015-004750-18.

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.

Preventing chemotherapy-induced nausea and vomiting with netupitant/palonosetron, the first fixed combination antiemetic: current and future perspective

Chemotherapy-induced nausea and vomiting (CINV) can be prevented in most patients receiving appropriate antiemetic treatment. However, inadequate uptake of current antiemetic guideline recommendations by physicians, and poor treatment adherence by patients, lead to suboptimal CINV control. There is an unmet need to optimize guideline-consistent use of antiemetics to improve CINV management and prevention. Herein, we provide an overview of CINV, then discuss oral and intravenous NEPA, the first fixed combination antiemetic, composed of netupitant/fosnetupitant and palonosetron. We describe the main pharmacologic and pharmacokinetic characteristics of NEPA, and review the clinical evidence supporting its use in the prevention of CINV.

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.

Effects of rolapitant administered orally on the pharmacokinetics of dextromethorphan (CYP2D6), tolbutamide (CYP2C9), omeprazole (CYP2C19), efavirenz (CYP2B6), and repaglinide (CYP2C8) in healthy subjects

Purpose

Rolapitant is a neurokinin-1 receptor antagonist indicated in combination with other antiemetic agents in adults for the prevention of delayed chemotherapy-induced nausea and vomiting. We evaluated the effects of rolapitant oral on the pharmacokinetics of probe substrates for cytochrome P450 (CYP) 2D6 (dextromethorphan), 2C9 (tolbutamide), 2C19 (omeprazole), 2B6 (efavirenz), and 2C8 (repaglinide) in healthy subjects.

Methods

This open-label, multipart, randomized, phase 1 study assessed cohorts of 20–26 healthy subjects administered dextromethorphan, tolbutamide plus omeprazole, efavirenz, or repaglinide with and without single, oral doses of rolapitant. Maximum plasma analyte concentrations (C_max) and area under the plasma analyte concentration–time curves (AUC) were estimated using noncompartmental analysis, and geometric mean ratios (GMRs) and 90% confidence intervals for the ratios of test (rolapitant plus probe substrate) to reference (probe substrate alone) treatment were calculated.

Results

Rolapitant significantly increased the systemic exposure of dextromethorphan in terms of C_max and AUC_0–inf by 2.2- to 3.3-fold as observed in GMRs on days 7 and 14. Rolapitant did not affect systemic exposure of tolbutamide, and minor excursions outside of the 80–125% no effect limits were detected for omeprazole, efavirenz, and repaglinide.

Conclusions

Inhibition of dextromethorphan by a single oral dose of rolapitant 180 mg is clinically significant and can last at least 7 days. No clinically significant interaction was observed between rolapitant and substrates of CYP2C9, CYP2C19, CYP2B6, or CYP2C8. CYP2D6 substrate drugs with a narrow therapeutic index may require monitoring for adverse reactions if given concomitantly with rolapitant.

Guideline for the prevention of acute chemotherapy-induced nausea and vomiting in pediatric cancer patients: A focused update

This update of the 2013 clinical practice guideline provides clinicians with guidance regarding the use of aprepitant and palonosetron for the prevention of acute chemotherapy-induced nausea and vomiting (CINV) in children. The recommendations were based on three systematic reviews. Substantive changes were made to the guideline recommendations including the inclusion of palonosetron to the 5-HT₃ antagonists recommended for children receiving highly emetogenic chemotherapy (HEC) and the recommendation of aprepitant for children 6 months of age or older receiving HEC. To optimize CINV control in children, future work must focus on closing critical research gaps.

Management of acute and delayed chemotherapy-induced nausea and vomiting: role of netupitant-palonosetron combination

Purpose

The purpose of this review is to summarize and discuss the recently published data (both original studies and reviews) on the oral medication NEPA, consisting of netupitant (a neurokinin-1 receptor antagonist [NK1RA], 300 mg dose) and palonosetron (5-hydroxytryptamine [serotonin or 5HT] type 3 receptor antagonist [5HT₃RA], 0.5 mg dose), in the prevention of the acute and delayed nausea and vomiting in patients receiving highly or moderately emetogenic chemotherapy.

Methods

This review was based on the very limited number of available published trials consisting of two Phase III studies and one Phase II dose-selecting trial.

Results

These studies demonstrated some therapeutic benefits of NEPA over related chemotherapy-induced nausea and vomiting (CINV) prophylaxis management, as well as its beneficial safety profile. In particular, compared with single-dose 0.5 mg palonosetron, the complete response rates for all phases of CINV for the first cycle of highly emetogenic chemotherapy (with cisplatin), as well as anthracycline–cyclophosphamide-based moderately emetogenic chemotherapy, were significantly higher for single-dose NEPA. The high efficacy of NEPA in terms of prevention of CINV continued throughout repeated cycles of highly and moderately emetogenic therapies.

Conclusion

It is currently recommended that patients who are administered highly emetogenic chemotherapy regimens should obtain a three-drug combination consisting of NK1RA, 5HT₃RA, and dexamethasone. The recently available oral combination of NEPA plus dexamethasone provides an additional pharmacological management option that could be considered in this scenario.

A Review of NEPA, a Novel Fixed Antiemetic Combination with the Potential for Enhancing Guideline Adherence and Improving Control of Chemotherapy-Induced Nausea and Vomiting

Combination antiemetic regimens targeting multiple molecular pathways associated with emesis have become the standard of care for prevention of chemotherapy-induced nausea and vomiting (CINV) related to highly and moderately emetogenic chemotherapies. Antiemetic consensus guidelines from several professional societies are widely available and updated regularly as new data emerges. Unfortunately, despite substantial research supporting the notion that guideline conformity improves CINV control, adherence to antiemetic guidelines is unsatisfactory. While studies are needed to identify specific barriers to guideline use and explore measures to enhance adherence, a novel approach has been taken to improve clinician adherence and patient compliance, with the development of a new combination antiemetic. NEPA is an oral fixed combination of a new highly selective NK1 receptor antagonist (RA), netupitant, and the pharmacologically and clinically distinct 5-HT3 RA, palonosetron. This convenient antiemetic combination offers guideline-consistent prophylaxis by targeting two critical pathways associated with CINV in a single oral dose administered only once per cycle. This paper will review and discuss the NEPA data in the context of how this first combination antiemetic may overcome some of the barriers interfering with adherence to antiemetic guidelines, enhance patient compliance, and offer a possible advance in the prevention of CINV for patients.

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.

Netupitant/Palonosetron

Each month, subscribers to The Formulary Monograph Service receive 5 to 6 well-documented monographs on drugs that are newly released or are in late phase 3 trials. The monographs are targeted to Pharmacy & Therapeutics Committees. Subscribers also receive monthly 1-page summary monographs on agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation/medication use evaluation (DUE/MUE) is also provided each month. With a subscription, the monographs are sent in print and are also available on-line. Monographs can be customized to meet the needs of a facility. A drug class review is now published monthly with The Formulary Monograph Service. Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. For more information about The Formulary Monograph Service, call The Formulary at 800-322-4349. The April 2015 monograph topics are edoxaban, diclofenac sodium injectable, olaparib, antihemophilic factor porcine, and blinatumomab. The Safety MUE is on edoxaban.

Review of oral fixed-dose combination netupitant and palonosetron (NEPA) for the treatment of chemotherapy-induced nausea and vomiting

Current guidelines recommend the combination of a neurokinin-1 (NK1) receptor antagonist (RA) and a 5-hydroxytryptamine-3 (5-HT3) RA, together with corticosteroids, in order to prevent chemotherapy-induced nausea and vomiting with anthracycline-cyclophosphamide and highly emetogenic chemotherapy, and it is to be considered with moderately emetogenic chemotherapy. Netupitant and palonosetron (NEPA) is a fixed-dose combination of netupitant, a novel, highly selective NK1 RA, and palonosetron, a new-generation 5-HT3 RA, targeting two major emetic pathways in a single oral capsule. In clinical trials, NEPA administered on day 1 together with dexamethasone was highly effective and well tolerated in the prevention of chemotherapy-induced nausea and vomiting in patients with solid tumors undergoing moderately emetogenic chemotherapy or highly emetogenic chemotherapy. NEPA offers maximal convenience, and as a simple guideline-based regimen, has the potential to improve adherence to guidelines.

Addressing the value of novel therapies in chemotherapy-induced nausea and vomiting

Chemotherapy-induced nausea and vomiting (CINV) is a troubling side effect of cancer treatment and is often poorly controlled. As a consequence, CINV is associated with substantially increased costs of care and significant interference with patients' lives. Inadequate control over CINV results from factors that include failure to provide guideline-adherent prophylactic medication and limitations in available therapies. Newer serotonin receptor antagonists, such as palonosetron, and addition of neurokinin-1 (NK-1) receptor antagonists to treatment have significantly decreased both acute and delayed CINV. A fixed-dose combination of palonosetron and a new NK-1 receptor, netupitant, is significantly superior to palonosetron alone and has small, but consistent, numerical advantages over aprepitant plus palonosetron for prevention of CINV. The combination of a serotonin receptor antagonist plus an NK-1 receptor antagonist has been shown to be cost-effective for prevention of CINV and the availability of a fixed-dose combination of netupitant and palonosetron may enhance this benefit.

Effect of netupitant, a highly selective NK₁ receptor antagonist, on the pharmacokinetics of midazolam, erythromycin, and dexamethasone

PURPOSE

Netupitant is a new highly selective neurokinin-1 receptor antagonist being studied for the prevention of nausea and vomiting in patients undergoing chemotherapy. In vitro studies suggest that netupitant inhibits the cytochrome P-450 isoenzyme 3A4 (CYP3A4). Because netupitant may be used with a variety of drugs, which may be substrates of CYP3A4, two studies were designed to establish the potential risk for drug-drug interaction with three different CYP3A4 substrates: midazolam, erythromycin, and dexamethasone.

METHODS

Both trials were three-period crossover studies performed in healthy subjects. In the first study, 20 subjects received netupitant and either midazolam or erythromycin. In the second study, 25 subjects received netupitant and dexamethasone. Serial blood samples were collected over the course of the two studies and pharmacokinetic parameters were determined for all analytes.

RESULTS

Netupitant, by inhibiting the CYP3A4, increased the C max and AUCinf of midazolam by 40 and 144 %, respectively, and the C max and AUCinf of erythromycin by 30 %. Netupitant was shown to increase the exposure to dexamethasone in a dose-dependent manner with the mean increase in AUC and C max by 72 and 11 %, respectively, on day 1 and by 138 and 75 %, respectively, on day 4 when co-administered with 300 mg of netupitant.

CONCLUSIONS

The results of these studies suggest that netupitant is a moderate inhibitor of CYP3A4 and therefore, co-administration with drugs that are substrates of CYP3A4 may require dose adjustments. Treatments were well tolerated in both studies.