Chemicals and reagents
Reference standards of almonertinib (over 98% purity), and HAS-719 (over 98% purity) were provided kindly by Jiangsu Hansoh Pharmaceutical Group Co. Ltd. (Lianyungang, China). Gefitinib (IS, over 98% purity) was supplied by Beijing Sunflower Technology Development Co. Ltd. (Beijing, China). The chemicals and solvents used for this study including methanol and acetonitrile (both LC–MS grade) were purchased from Merck Company (Darmstadt, Germany). Formic acid with LC–MS grade was supplied by Anaqua Chemicals Supply (ACS, American). Deionized water was generated using a Milli-Q water purifier from Millipore (Bedford, USA).
UPLC-MS/MS conditions
The UPLC–MS/MS system was performed on a Waters XEVO TQS triple quadruple mass spectrometer and an ultra-performance liquid chromatograph (Waters Corp., USA). The separations of the analytes and IS were conducted using an Acquity UPLC BEH C18 column (2.1 mm × 50 mm, 1.7 µm, Waters Corp., USA) at 40°C with a mobile phase flow rate of 0.4 mL/min. A gradient elution was carried out using acetonitrile (A) and 0.1% formic acid aqueous solution (B) as mobile phases. Linear gradient scheme was set and conducted as follows: 0–0.5 min, 10% A; 0.5–1.0 min, 10–90% A; 1.0–1.5 min, 90% A;1.5–1.6 min, 90 − 10% A; 1.5–2.0 min, 10% A. The injection volume was 1.0 µL and the temperature of the autosampler was 10°C. The mass spectrometry was performed using an electrospray ionization source in the positive ionization and multiple reaction monitoring (MRM) mode with ion transitions of m/z 526.01 → 72.04 for almonertinib, m/z 512.18 → 455.08 for HAS-719, and m/z 447.16 → 128.11 for IS. The optimized parameters for the mass spectra of almonertinib, HAS-719 and IS included: cone voltage was 10 V for each analyte, and collision energy were 26 V, 23 V and 22 V, respectively. The mass spectrograms of almonertinib, HAS-719 and IS were presented in Table 1.
Table 1
Specific mass spectrometric parameters and retention times (RTs) for the analytes and IS, including cone voltage (CV), and collision energy (CE).
Analytes | Precursor ion | Product ion | CV (V) | CE (V) | RT (min) |
---|
Almonertinib | 526.01 | 72.04 | 10 | 26 | 1.21 |
HAS-719 | 512.18 | 455.08 | 10 | 23 | 1.20 |
IS | 447.16 | 128.11 | 10 | 22 | 1.14 |
Preparation of working solutions and quality control (QC) samples
For the preparation of 1.0 mg/mL of standard stock solutions, almonertinib and HAS-719 were accurately weighed and dissolved in methanol, respectively. Then, a deeper dilution was continued with methanol to obtain other concentrations of the standard solution. The same procedures were used to prepare the IS working solution (200 ng/mL). Eight calibrators by spiking 10% of standard solution volume into blank rat plasma were prepared at nominal plasma concentrations of 0.5–200 ng/mL for almonertinib and 0.5–100 ng/mL for HAS-719. Quality control (QC) samples containing the lower limit of quantification (LLOQ) were formulated at four levels of 0.5, 1.0, 40 and 160 ng/mL for almonertinib and 0.5, 1.0, 40 and 80 ng/mL for HAS-719, respectively. The stock and working solutions were stored in refrigerators set 4°C.
Sample processing
Prior to the treatment of samples, the samples were transferred from the − 80°C refrigerator and thawed at room temperature. Then, 20 µL of IS solution, 100 µL of plasma and 300 µL of acetonitrile were added to a 1.5 mL centrifuge tube and thoroughly mixed by vortexing for 3 min. The mixture was centrifuged at 13,000 × g for 10 min after thorough precipitation of the proteins by acetonitrile, and then 100 µL supernatant was transferred to a new autosampler vial, where 1.0 µL of the injection volume was used for UPLC-MS/MS investigation.
Method validation
Methodological validation of the bioassay was undertaken in compliance with the FDA regulatory principles for the assessment of selectivity, LLOQ, calibration curve, accuracy, precision, matrix effect, recovery and stability of the analytes in matrix [19].
The half-maximal inhibitory concentration (IC50) and inhibitory mechanism of almonertinib by nicardipine in RLM
The rat liver microsomes (RLM) incubation system was set up, then the drug was added to the system and incubated for 45 min as to determine the metabolism of the drug by the microsomes. The system with a final volume of 200 µL contained 1 M PBS, almonertinib (0.1, 0.2, 0.5, 1.0, 2.0, 5, 10, 20 µM), RLM (0.3 mg/mL), and NADPH (1 mM) in incubation system. The system was used to detect the Michaelis-Menten constant (Km) values of almonertinib in RLM. The mixture without NADPH was preincubated for 5 min at 37°C before adding 1 mM NADPH to activate the reaction. After incubation at 37°C for 40 min, the mixture was ceased by rapidly cooling to -80°C, and was prepared by adding with 20 µL of IS solution (200 ng/mL) and 400 µL of acetonitrile. Following centrifugation at 13000 × rpm for 10 min, an upper supernatant of 100 µL was taken for determination by UPLC-MS/MS.
For the detection of possible DDIs between almonertinib and nicardipine, the concentration of almonertinib was 5.25 µM in RLM, according to the Km value, while the concentrations of nicardipine were set at 0.01, 0.1, 1.0, 10, 25, 50 and 100 µM. To investigate the potential inhibitory mechanism, the concentrations of almonertinib and nicardipine were identified based on the Km and IC50 values, respectively. The concentrations of nicardipine were 0, 0.60, 1.19, 2.38 and 4.76 µM, while the concentrations of almonertinib were 1.31, 2.63, 5.25, 10.50 and 21.00 µM. The sample was prepared in accordance with the experiment mentioned above.
Effect of nicardipine on the pharmacokinetics of almonertinib in rats
Ten healthy male Sprague-Dawley (SD) rats weighing 200–220 g were obtained from the Experimental Animal Center of the First Affiliated Hospital of Wenzhou Medical University (Zhejiang, China). The rats were permitted to feed and drink freely, with a laboratory temperature of 25°C and a light/dark cycle of 12 h. During the experiments, the animals were operated in accordance with the animal ethics guidelines formulated by the Animal Care and Use Committee of the First Affiliated Hospital of Wenzhou Medical University (WYYY-IACUC-AEC-2023-014). Almonertinib and nicardipine were formulated in 0.5% sodium carboxymethylcellulose (CMC-Na) solution. Before the experiment started, ten rats were randomly divided into two groups: Group A (orally given 11 mg/kg almonertinib alone); Group B (orally given 11 mg/kg almonertinib and 6 mg/kg nicardipine). Administration of the drug was preceded by a 12-h fast with no restriction on water. Ten rats were given almonertinib 30 min after oral administration of nicardipine or 0.5% CMC-Na solution. Pre-dose (marked as 0 h) and 0.33, 0.67, 1, 1.5, 2, 3, 4, 6, 8, 12 and 24 h post-dose, 0.3 mL of blood samples were obtained through the caudal vein, which were collected into tubes containing heparin and centrifuged at 8000 × rpm at 4°C for 10 min. Afterwards, plasma was shifted to tubes and stored at -80°C until later investigation.
Euthanasia of experimental animals was performed using the anesthesia method according to the AVMA Guidelines for the Euthanasia of Animals. After completion of the experiment, all experimental animals were euthanized by intravenous pentobarbital (150 mg/kg). After ensuring that the animals were free of life pointers, they were packaged and cremated. The entire experimental process of the animals strictly adhered to the regulations for the care and use of laboratory animals as reviewed and approved by the Ethics Committee of The First Affiliated Hospital of Wenzhou Medical University (Wenzhou, China).
Statistical Analysis
The Michaelis–Menten, IC50, Lineweaver-Burk plots were obtained using GraphPad Prism 8.0 software. Non-compartmental analysis was performed by using Drugs and Statistics (DAS) software (version 3.0 software, Shanghai University of Traditional Chinese Medicine, China) to obtain pharmacokinetic parameters. Mean plasma concentration-time curves were generated with Origin 8.0, and independent samples t-test was used to statistically investigate the parameters between the two groups. All data were shown as mean ± SD and analyzed using SPSS 24.0.