| Objective:The purpose of this work was to study the consistency of domestic nifedipine sustained release tablets and the ordinary nifedipine tablets with the Bayer nifedipine sustained release tablets (original drug), the study was composed of the consistency in vitro:nifedipine impurities, dissolution, crystal forms, content, the consistency in vivo:bioequivalence and bioavailability, the evaluation of the gap between domestic nifedipine tablets and the original nifedipine tablets, the exploration of the main indicators which value the consistency of generics and the original drug, to the study to provide experimental evidence for the production and development of drugs.Method:1. nifedipine impurities were checked:a specificity, high sensitivity HPLC-MS analysis method was established for checking nifedipine impurities Ⅰ and Ⅱ, which were separated on a Phenomenex C18(2) column (150×4.6mm,5μm) at column temperature of25℃by acetonitrile:water (55:45, v/v), and the flow rate was0.8mL·min-1, and10μL solvent was injected into HPLC for analysis. The impurities of these three nifedipine tablets were analysed and determinationed by the established method.2. Dissolution of domestic nifedipine sustained release tablets and the Bayer nifedipine sustained release tablets during24h, and ordinary nifedipine tablets during2h were detected by HPLC method. The chromatographic conditions were:column was Phenomenex C18(2) column (150x4.6mm,5μm), mobile phase was acetonitrile:0.3%triethylamine (60:40, v/v), detection wavelength was333nm, the flow rate was0.8mL·min-1, and20μL was injected into HPLC for analysis.3. Crystal forms of bulk drug and the three tablets were studied by X-ray diffraction method and differential scanning calorimetry method to compare the different crystal forms of the four substances. 4. Content determination of three nifedipine oral formulations were studied, which the chromatographic conditions were described as below. The analytical column was the Diamonsil C18(2) column (150×4.6mm ID,5μm), mobile phase was acetonitrile:water with5mmol·L-1acetic acid ammonium (60:40, v/v), flow rate was0.8mL·min-1,10μL solvent was injected into the HPLC-MS/MS for analysis at column temperature25℃.5. High performance liquid chromatography methods were developed and validated for the quantification of nifedipine in human plasma. Nifedipine was separated on Diamonsil C18(2) column (150×4.6mm,5μm) by acetonitrile:5mmol·L-1ammonium acetate (60:40, v/v), the flow rate was0.8mL·min-1, and the injection volume was10μL. Mass spectrometer was operated using electrospay ionization (ESI) with negative ionization mode at the following parameters. The voltage of EMV was400V. The fragment voltages were all100V, collision gas with energy of5eV for nifedipine and20eV for acetaminophen. The following ion transitions (m/z) were345.1'222.2for nifedipine and150.1'107.1for acetaminophen. Specificity, sensitivity, linearity, precision, accuracy, stability and dilution effect were validated.6. The bioequivalence of nifedipine oral formulations was studied,20healthy male volunteers were randomly divided into two groups. A single dose, double-cross test was designed in the first and the second period, while20mg domestic nifedipine sustained release tablets or Bayer nifedipine sustained release tablets were took, ordinary nifedipine tablets were took in third period for all volunteers. The blood samples (5mL) were collected at the given time points. The samples were deposed by a liquid-liquid extraction method and10μL was injected into HPLC for analysis. Bioequivalence of groups between administrate domestic nifedipine sustained release tablets and Bayer nifedipine sustained release tablets, ordinary nifedipine tablets and Bayer nifedipine sustained release tablets were analyzed by Drug and statistic software (DAS2.0).Results:1. Nifedipine impurities of three Nifedipine tablets met the quality requirements of2010edition of Chinese Pharmacopoeia, However, the content of the impurities of the original nifedipine tablets were significantly less than of domestic nifedipine sustained release tablets and ordinary nifedipine tablets.2. The results of dissolution showed that the two sustained-release tablets had significantly sustained-release effect, as the release characteristics of domestic nifedipine sustained-release tablets were close to the controlled-release characteristics, Bayer nifedipine sustained-release tablets were typical sustained-release tablets. Cumulative dissolution percentages of the ordinary nifedipine tablets were82.19%in one hour, which met the requirement of dissolution.3. The polymorph test results of three nifedipine oral formulations showed that the positions of the main diffraction peaks of bulk drugs were similar with domestic nifedipine sustained release tablets and Bayer nifedipine sustained release tablets, which indicated that there were similar crystal forms between the domestic nifedipine sustained release tablets and Bayer nifedipine sustained release tablets. However, there were significantly different crystal forms between ordinary nifedipine tablets and other two nifedipine sustained release tablets. The results of DSC and X-ray power diffraction were consistent.4. The content of the three nifedipine tablets met the requirements of the2010edition of Chinese Pharmacopoeia, which the percentage of the labeled amount met the range of90%-110%.5. The established HPLC-MS/MS method was sensitive, selectivity, accurate and stability in the study, which was applied for the determination of nifedipine level in human plasma.6.20healthy volunteers separately took a single oral dose of Bayer nifedipine sustained release tablets, domestic nifedipine sustained release tablets and ordinary nifedipine tablets, the main pharmacokinetic parameters of them were that t1/2were (6.70±2.22) h,(9.63±8.12) h and (5.43±1.31) h; Tmax were (2.80±0.50) h、(2.70±0.47) h and (1.87±1.21) h; Cmax were (76.69±19.50) ng·mL-1,(75.56±17.60) ng·mL-1and (277.22±93.26) ng·mL-1; AUC0-36were (534.13±159.94) ng·mL-1·h,(526.68±154.83) ng·mL-1·h and (1292±602.86) ng·mL-1·h; AUC0-∞were (551.68±174.34) ng·mL-1·h,(610.83±353.90) ng·mL-1·h and (1303.71±611.54) ng·mL-1·h, separately. The two kinds of nifedipine sustained release tablets were bioequivalent. Bayer sustained release nifedipine tablets and ordinary nifedipine tablets were not bioequivalent, the relative bioavailability of ordinary nifedipine tablets was higher.Conclusion:The results of consistency of two nifedipine sustained-release tablets in vitro showed that nifedipine impurity and content all met the relevant provisions of the2010Chinese Pharmacopoeia. Both of the results of dissolutions and crystal forms were similar, and were bioequivalent in vivo. The results of consistency of domestic nifedipine tablets in vitro showed that nifedipine impurities and dissolution determination and determination all met the relevant provisions of the2010Chinese Pharmacopoeia, while the crystal forms were different with the other two sustained-release tablets, and were not bioequivalent in vivo, which indicated that polymorphs and formulations of nifedipine were the critical factors for the nifedipine dynamics in vivo. |
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