This was a phase I, randomized, open-label, two-treatment, two-period, two-sequence, crossover study conducted at Peking University (PKU) Care, Luzhong Hospital, China from 8 November 2020 to 7 December 2020 in healthy Chinese participants (CTR20202108). The investigational FDC was a test formulation [ezetimibe/rosuvastatin which contained 10 mg of both the drugs (10 mg/10 mg)] and was compared with the reference formulations [individual rosuvastatin (Crestor®, 10 mg) and ezetimibe (Ezetrol®, 10 mg]. This study was conducted in accordance with the ethical principles derived from international ethics guidelines, including the Declaration of Helsinki, and the International Council for Harmonization (ICH) guidelines for Good Clinical Practice (GCP), all applicable laws, rules, and regulations. The study received approval from the institutional ethics committee of Peking University Care, Luzhong Hospital (PKULZH-IRB-SOP-AF-013/3.0-03). Informed written consent was obtained.

The subjects were randomized to either of the two-treatment sequences. Sequence 1 consisted of FDC administration followed by the individual formulations (test–reference), respectively in period 1 and 2. Whereas, sequence 2 consisted of administration of individual formulations followed by the FDC (reference–test), respectively, in period 1 and 2. The subjects were randomized to either sequence 1 or sequence 2 in a 1:1 ratio. The tablets were administered orally to the healthy subjects under fasting conditions. The treatment period consisted of 5 days including one treatment day in each period, followed by a washout period of 10 days between each administration.

Healthy Chinese male and female subjects of age 18 and above, body weight between 50.0 and 95.0 kg (kg) for male (inclusive), 45.0 and 90.0 kg for female (inclusive), were enrolled in this study. All the subjects were certified as healthy by a comprehensive medical assessment which included a detailed medical history and complete physical examination. Female participants were required to use at least one contraception method for 3 months after the dosing, except if the subject was menopausal or had undergone sterilization at least 3 months earlier. The subjects were excluded if they had any history or presence of any acute illness, disorder, or any drug abuse. Breastfeeding or pregnant subjects were excluded from the study. Informed written consent was obtained at the time of study enrolment.

The study aimed to evaluate the Cmax, AUC0–t, and AUC0–∞ of rosuvastatin, unconjugated and total ezetimibe from FDC and individual formulations (treatment 1 vs treatment 2) under fasting conditions. The secondary endpoints for this study were to evaluate the other pharmacokinetic (PK) parameters including t1/2, Tmax, and λz. The safety assessments included adverse events (AEs)/treatment-emergent adverse events (TEAEs), vital signs, 12-lead electrocardiogram (12-ECG), and clinical laboratory evaluations (hematology, biochemistry, urinalysis, coagulation).

Blood samples were collected at the following time points: 0 h (pre-dosing) and 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 8, 12, 24, 36, 48, and 72 h (post-dosing) for rosuvastatin and 0 h (pre-dosing) and 0.25, 0.5, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 4, 5, 6, 8, 10, 12, 24, 48, 72, and 96 h (post-dosing) for ezetimibe. The PK parameters such as Cmax, AUC0–t, AUC0–∞, t1/2, Tmax, and λz were calculated using the noncompartmental methods from plasma rosuvastatin, unconjugated ezetimibe, and total ezetimibe concentrations obtained after single dose administration. Total ezetimibe was calculated from the sum of free ezetimibe and ezetimibe glucuronide, taking into consideration the adjustment per molecular weight for each analyte respectively.

Bioanalytical methods were performed in the laboratory of Covance Pharmaceutical Research and Development (Shanghai). Liquid chromatography with tandem mass spectrometry (LC–MS/MS) was used for analysis. PK samples were used for testing analytical method performance such as comparability and incurred sample reproducibility.

All the subjects were monitored for laboratory parameters, vital signs, ECGs, and AEs. AEs were coded according to the Medical Dictionary for Regulatory Activities (MedDRA, version 23.1). Their severity was graded according to the Common Terminology Criteria for Adverse Events (CTCAE, version 5.0). The number (%) of participants experiencing TEAEs was summarized by primary system organ class, preferred term, and treatment. For laboratory parameters, vital signs, and ECGs, incidences of potentially clinically significant abnormality (PCSA) were evaluated. The safety evaluation focused on the TEAE period, defined as the time interval from the investigational medicinal product (IMP) administration of each treatment period up to day 5 (inclusive).

The sample size was calculated on the basis of within-subject standard deviation (SDw) of 0.27 for rosuvastatin and unconjugated ezetimibe, and SDw of 0.22 for total ezetimibe, which was estimated from pooled SDw values of recent studies. The assumption of true difference between E10/R10 and coadministration of individual tablets on rosuvastatin and total ezetimibe is 5%, and the true difference on unconjugated ezetimibe is 7.5%, which was based on a previous Sanofi in-house bioequivalence study, ZNV-P5-545. A total of 62 subjects were required to achieve an overall power of 85% to conclude the bioequivalence of FDC to the co-administered individual tablets. But considering the potential subject dropout rate, 68 subjects were enrolled.

PK parameters of rosuvastatin, unconjugated and total ezetimibe were summarized using descriptive statistics (such as mean, geometric mean, median, standard deviation [SD], standard error of mean [SEM], coefficient of variation [CV], minimum, and maximum) for each treatment. Listings of individual ratios (FDC versus co-administration treatment) for Cmax, AUC0–t, and area under the plasma concentration versus time curve extrapolated to infinity (AUC0–∞) were provided by subject, sequence, and summarized using descriptive statistics by treatment. The difference between FDCs and individual formulations under fasting conditions was assessed on log-transformed parameter with a linear mixed effects model with fixed term for treatment, sequence, period, and with an unstructured matrix of treatment-specific variances and covariances for subject within sequence blocks, using SAS® version 9.4.

For Cmax, AUC0–t, and AUC0–∞ estimates and 90% confidence intervals (CI) for geometric mean ratio of treatments (test versus individual reference formulations) were obtained by computing estimates and 90% CIs for the difference between treatment means within the mixed effects model framework, and then converting to the ratio scale by the antilog transformation. If the 90% CI of the ratio for Cmax, AUC0–t, and AUC0–∞ of rosuvastatin, unconjugated ezetimibe, and total ezetimibe all were within the range of 0.8–1.25, the bioequivalence of test formulation to co-administration of reference formulations was established. Histograms of Tmax and t1/2 values were represented by formulation. In addition, the histograms of differences in Tmax between formulations (test versus individual reference formulations) were also provided.