Assessment of CYP-Mediated Drug Interactions for Evocalcet, a New Calcimimetic Agent, Based on In Vitro Investigations and a Cocktail Study in Humans

Comparison of the Oral Calcimimetics Evocalcet and Cinacalcet in East Asian Patients on Hemodialysis with Secondary Hyperparathyroidism

Introduction

Evocalcet is an oral calcimimetic agent with proven efficacy and safety in treating secondary hyperparathyroidism (SHPT) in Japanese patients on dialysis.

Methods

This randomized, double-blind, intrapatient dose-adjustment, parallel-group, international multicenter study compared the efficacy and safety of evocalcet versus cinacalcet for 52 weeks in East Asian hemodialysis patients with SHPT.

Results

In total, 203 and 200 patients were randomized to receive evocalcet or cinacalcet, respectively (overall, 70.1% had baseline intact parathyroid hormone (PTH) levels ≥500 pg/ml, with no between-group difference). Mean percentage changes in intact PTH levels from baseline were -34.7% and -30.2% in the evocalcet and cinacalcet groups at 52 weeks (between-group difference -4.4%, 95% confidence interval [CI] -13.1%, 4.3%, below the predefined 15% noninferiority margin). Overall, 67.3% and 58.7% of patients in the evocalcet and cinacalcet groups, respectively, achieved ≥30% decrease in intact PTH levels from baseline (between-group difference 8.6%; 95% CI -1.8%, 19.1%). No major safety concerns were observed. Gastrointestinal adverse events (AEs) were significantly less frequent with evocalcet compared with cinacalcet (33.5% vs. 50.5%, P = 0.001), whereas the incidence of hypocalcemia did not differ.

Conclusion

Evocalcet might be a better alternative to cinacalcet for East Asian patients on hemodialysis with SHPT.

Pharmacokinetic and Pharmacodynamic Drug-Drug Interactions: Research Methods and Applications

Because of the high research and development cost of new drugs, the long development process of new drugs, and the high failure rate at later stages, combining past drugs has gradually become a more economical and attractive alternative. However, the ensuing problem of drug-drug interactions (DDIs) urgently need to be solved, and combination has attracted a lot of attention from pharmaceutical researchers. At present, DDI is often evaluated and investigated from two perspectives: pharmacodynamics and pharmacokinetics. However, in some special cases, DDI cannot be accurately evaluated from a single perspective. Therefore, this review describes and compares the current DDI evaluation methods based on two aspects: pharmacokinetic interaction and pharmacodynamic interaction. The methods summarized in this paper mainly include probe drug cocktail methods, liver microsome and hepatocyte models, static models, physiologically based pharmacokinetic models, machine learning models, in vivo comparative efficacy studies, and in vitro static and dynamic tests. This review aims to serve as a useful guide for interested researchers to promote more scientific accuracy and clinical practical use of DDI studies.

Studies on potential interaction between cinacalcet hydrochloride and diclofenac sodium

Cinacalcet (CT) is an important drug for the treatment hyperparathyroidism. Only few studies havereported thepotential interaction between CT and other potentially coadministered drugs. In this study, the potential of invitro interaction between CT and DF sodium (DF-Na) was investigated. An ion pair salt of CT with DF was obtained by mixing the two compounds in solution; the product was fully characterized by HPLC analysis, UV, FTIR, NMR spectroscopy in addition to DSC. The solubility and partition coefficients were found to significantly decrease and increase, respectively, for the obtained ion pair salt in comparison to the parent compounds. Dissolution studies in phosphate buffer pH 6.8 revealed a significant decrease in the dissolution of an already poorly water soluble drug (decrease to ~20% of the original). Permeation studies, through Caco-2 cells monolayer, revealed a significant decrease in permeation of CT when coexisted with DF (almost to half). Apparent permeability coefficient (Papp) decreased from 3.6 × 10^-6 to 1.8 × 10^-6 cm/s. Interestingly, a structure for the formed CT-DF salt that could explain the above findings (increase in lipophilicity), could be proposed based on structural modelling, molecular dynamic simulations and NMR proton chemical shifts analysis.

Development of evocalcet for unmet needs among calcimimetic agents

INTRODUCTION

The calcium-sensing receptor is an important treatment target for secondary hyperparathyroidism (SHPT) in patients undergoing dialysis. In addition to vitamin D receptor activator, cinacalcet has recently been widely used for SHPT management, and the significant suppression of parathyroid hormone (PTH) with better control of serum calcium and phosphorus has been reported. However, low adherence and insufficient dose escalation mainly due to frequent gastrointestinal adverse events, still remain as major issues. To overcome these unmet needs, we have developed a new oral calcimimetic agent evocalcet, which has recently been approved by the Pharmaceutical Affairs Act in Japan.

AREAS COVERED

PubMed was searched from inception until April 2020 with the word evocalcet to summarize the development of this new calcimimetic agent, its pharmacokinetics, and the results of clinical trials, along with an overview of the differences among calcimimetic agents. This review also includes the management of SHPT with a focus on calcimimetics.

EXPERT OPINION

Evocalcet evoked fewer gastrointestinal-related adverse events while suppressing PTH at a lower dose than cinacalcet. These data suggest evocalcet may contribute to better adherence and sufficient dose escalation in patients with SHPT. Whether or not evocalcet improves clinical outcomes remains to be elucidated.

Gut Microbiota-Mediated Drug-Drug Interaction between Amoxicillin and Aspirin

The effects of antibiotics on the intestinal flora can create potential drug-drug interactions. The combination of amoxicillin and aspirin is high and there is a high probability of interaction. We used 16S rRNA, incubation experiments and liquid chromatography-tandem mass spectrometry to analyze rat biological samples to characterize the effect of amoxicillin on the pharmacokinetics of aspirin metabolites. We first discovered that amoxicillin reduced the species and number of intestinal flora in rats, such as reducing the abundance of Helicobacter pylori and Prevotella_copri. After 12, 24, and 36 hours of incubation, the remaining amount of aspirin in the aspirin and amoxicillin treatment groups decreased, and salicylic acid production increased, suggesting that aspirin is metabolized by the intestinal flora, and the main metabolite is salicylic acid. As the incubation time prolonged, the reduction of aspirin and the production of salicylic acid in the amoxicillin treatment group were slower. It is indicated that the metabolic activity of aspirin through the intestinal flora is slowed down after administration of amoxicillin. The pharmacokinetic experiments showed that after administration of amoxicillin, the area under the salicylic acid curve increased by 91.38%, the peak concentration increased by 60.43%, and the clearance rate decreased by 43.55%.The results demonstrated that amoxicillin affected the pharmacokinetics of aspirin active metabolite salicylic acid by slowing down the metabolic activity of intestinal flora on aspirin. The interaction between amoxicillin and aspirin mediated by the intestinal flora may affect the efficacy of aspirin and cause more significant adverse effects.

Evocalcet: A New Oral Calcimimetic for Dialysis Patients With Secondary Hyperparathyroidism

Patients with chronic kidney disease often develop secondary hyperparathyroidism (SHPT), marked by high levels of circulating parathyroid hormone (PTH) and increased risk of morbidity and mortality. Patients with SHPT are treated with a therapeutic combination that commonly includes calcimimetics, which have recently become popular in clinical settings, and other agents such as vitamin D preparations. Calcimimetics are a drug class that reduces PTH levels by targeting the calcium‐sensing receptor. Cinacalcet, a representative calcimimetic, is widely used; however, a high incidence of upper gastrointestinal (GI) tract‐related adverse events (AEs) can result in insufficient dosage and poor long‐term compliance. The newly approved evocalcet has equivalent efficacy to cinacalcet at a lower clinical dose, with improved bioavailability, fewer upper GI tract‐related AEs, and fewer safety concerns. This review gives an overview of calcimimetic agents, with a special focus on evocalcet, and describes the clinical advantages of evocalcet in the treatment of dialysis patients with SHPT.

Efficacy and safety of evocalcet in Japanese peritoneal dialysis patients

BACKGROUND

Secondary hyperparathyroidism (SHPT) is a serious and common complication in patients receiving peritoneal dialysis (PD). Cinacalcet is currently the recommended therapy for SHPT; however, gastrointestinal (GI)-related symptoms can result in low adherence and high discontinuation rates. Evocalcet is a novel calcimimetic agent that has non-inferior efficacy while providing a more tolerable safety profile.

METHODS

This was a multicenter, intra-subject dose-adjustment treatment study evaluating the efficacy and safety of 1-8 mg evocalcet orally administered once daily for 32 weeks for the treatment of SHPT in PD patients. Patients then entered a 20-week extension period (dose range 1-12 mg). The primary endpoint was the proportion of patients who achieved a mean intact parathyroid hormone (iPTH) level of 60-240 pg/mL during the evaluation period (weeks 30-32). Secondary efficacy endpoints included the proportion of patients achieving ≥ 30% decrease in iPTH levels.

RESULTS

A total of 39 Japanese PD patients with SHPT received evocalcet. The target mean iPTH level of 60-240 pg/mL was achieved by 71.8% (28/39) of patients during the evaluation period and 83.3% (20/24) of patients at week 52. The proportion of patients who achieved ≥ 30% decrease in iPTH levels from baseline was 74.4% (29/39) during the evaluation period and 87.5% (21/24) at week 52. Adverse drug reactions occurred in 46.2% (18/39) of patients, with most being of mild-to-moderate severity including GI-related events.

CONCLUSION

This study shows the long-term efficacy and safety of evocalcet when orally administered to PD patients with SHPT once daily.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov: NCT02549417, https://clinicaltrials.gov/ct2/show/NCT02549417 ; JAPIC: JapicCTI-153016, http://www.clinicaltrials.jp/user/showCteDetailE.jsp?japicId=JapicCTI-153016 .

[Pharmacological and clinical profiles of a novel calcimimetic, evocalcet (ORKEDIA®)]

Calcimimetics allosterically activate the calcium receptor (CaR) and inhibit the secretion of parathyroid hormone (PTH). Cinacalcet hydrochloride (cinacalcet) has been approved as the first calcimimetic drug for the treatment of secondary hyperparathyroidism (SHPT) in patients with hemodialysis. Cinacalcet improved the achievement of target serum PTH and Ca levels and helped drastically reduce the number of parathyroidectomies. However, cinacalcet has side effects involving the gastrointestinal tract, such as nausea and vomiting, which makes it difficult to increase the dose and may result in reduced compliance. Evocalcet has been developed to improve defects of cinacalcet for management of SHPT. Evocalcet acts as an allosteric modulator of CaR, just like cinacalcet. However, its metabolic pathway is different from that of cinacalcet. The metabolism of evocalcet by cytochrome P450 is very low, so evocalcet has higher bioavailability. As a result, its pharmacologically effective dose for the inhibition of PTH secretion is lower than that of cinacalcet. Evocalcet had less of an effect on the gastrointestinal tract than cinacalcet because of the reduced dose required. In a clinical trial with a randomized, double-blind, head-to-head comparison study, it was also confirmed that the incidence of gastrointestinal-related adverse events was lower in the evocalcet group than in the cinacalcet group. Evocalcet may thus be a potent option for the management of SHPT.