| With the aging of population and the improvement of living standards, the incidence of cardiovascular disease showed a continuous increase in the trend and will continue to grow rapidly in 10 years. Angina pectoris is a more serious cardiovascular disease in clinic. Chronopharmacology has shown that many diseases are prone to occur in the early morning such as hypertension, angina pectoris, myocardial ischemia. The peak incidence of angina pectoris in patients is 2:00-10:00a.m. Pulsatile drug delivery system can release drugs in accordance with the need for treatment of disease, which achieved the purpose of effective treatment. Trimetazidine hydrochloride is the first anti-angina drug acting on myocardial cell metabolism. It can increase coronary blood flow and improve myocardial oxygen supply and demand balance to protect the myocardium. Therefore, trimetazidine hydrochloride is suitable for pulsed delivery for the treatment of angina pectoris, which has high clinical value for its research and development.We select trimetazidine hydrochloride as the model drug. The pulsatile release tablets were prepared by film coating technology, by optimizing the preparation and formulation, to achieve pulsatile drug system. Firstly, the analysis methods of pulsatile tablets in vitro and in vivo were studied and validated. Subsequently, the quality and stability of pulsatile tablets were investigated. And then, the release mechanism in vitro was studied by mathematical model. Finally, with commercial tablets as control group, the pharmacokinetics of pulsatile release tablets in Beagle dogs was studied to evaluate the bioequivalence and relative bioavailability.1. Preformulation studyHPLC methods were established for the determination the content and related substances of trimetazidine hydrochloride. The results of method validation demonstrated that the HPLC methods met the determination requirements with good specificity, sensitivity and accuracy. Trimetazidine hydrochloride had good solubility and did not change with the pH value change. Trimetazidine hydrochloride was stable and easy to absorb moisture, therefore, it needed to seal preservation. The dissolution curves of commercial tablets were examined in four dissolution media and were not affected by pH changes. All above can provide the basis for the prescription screening, the determination of preparation process and the release of media of trimetazidine hydrochloride pulsatile tablets.2. Preparation of trimetazidine hydrochloride pulsatile tabletsThe excipients compatibilities with trimetazidine hydrochloride were determined by compatibility test. The amount of sodium carboxymethyl starch and low-substituted hydroxypropylcellulose were determined by disintegration test and the time delay of drug release. The amount of microcrystalline cellulose and mannitol were determined by the fluidity of powders and friability testing. The trimetazidine hydrochloride pulsatile tablets were prepared by film coating method. The type and dosage of plasticizing agent, the ratio of Eudragit L100 to ethyl cellulose and the weight gain of coating were researched to optimize the formulation. And then, the orthogonal test was used to furtherly optimize the composition of the coat with drug lag time as evaluation index. RESULTS:The optimum formulation was as follows:trimetazidine hydrochloride 20 mg, microcrystalline cellulose 50 mg, mannitol 17.6 mg, sodium carboxymethyl starch 15 mg, low-substituted hydroxypropylcellulose 15 mg, silicon dioxide 1.2mg, and magnesium stearate 1.2mg. The formulation of the coat was as follows:Eudragit L100 6.72 g, ethyl cellulose 2.88g, polyethylene glycol 60000.96 g. the weight of coating gain was 8.0%.The hardness of tablets was 6-8kg based on the friability and release profile of trimetazidine hydrochloride pulsatile tablets. The coating processes were determined by the time delay of drug release. The drug contents of three batches were 100.24%, 99.16%,99.59%, respectively. The total amount of impurities were 0.11%,0.10%, 0.12%, respectively and the maximum amount of single impurities were 0.04%, 0.04%,0.05%, respectively. The in vitro release curves of three batches of samples showed good reproducibility both within and between batches. The process was reasonable and suitable for industrial production.3. Study on quality and stabilityThe qualities of trimetazidine hydrochloride pulsatile release tablets were studied. The drug content and the amount of related substances of trimetazidine hydrochloride were measured by HPLC methods. The content method was linear in the range of 60.864 ?g/ml to 142.016 ?g/ml(r=0.9999), the average recovery was 99.55%, and the value of RSD was 0.59%. The system showed good tolerance by different chromatographic columns and mobile phase. The detection method of related substances had good specificity and accuracy, and the system had good tolerance. The UV-VIS method was established for the determination of release rate of trimetazidine hydrochloride. This method had good linear, specificity and accuracy in water, 0.1mol/LHCl, pH 6.8 phosphate buffer. The method validation demonstrated that the established method had good specificity, sensitivity and linear, and the resolution met the requirements, which was suitable for the study on quality of trimetazidine hydrochloride pulsatile tablets.Release mechanism was investigated via observing the coating film under a microscope. The coating film was complete and smooth before release. However, a large number of pores were formed on the surface of coating film after released in pH 6.8 phosphate buffer, because Eudragit L100 was dissolved in pH 6.8 phosphate buffer. Water can penetrate into the core through the pores, causing the disintegrant swelling and the coating rupture, and then releasing the active ingredient. Release mechanism showed that the release kinetics of trimetazidine hydrochloride pulsatile release tablets was fitted to Difusion/Relaxations equation and Peppas equation, which indicated that the mechanism of drug release is dominated by diffusion.Impact factors test, accelerated test and long-term test of trimetazidine hydrochloride pulsatile tablets were carried out respectively and the results showed that the formulation had good stability.4. Pharmacokinetic study in beaglesThe HPLC method was established for the determination of trimetazidine hydrochloride in plasma. Trimetazidine hydrochloride pulsatile release tablets and commercially available tablets were orally administered to the Beagle dogs, the concentrations of drug in plasma obtained from Beagle dogs. Then, the plasma concentrations were determined via HPLC. A double-cycle randomized crossover study was conducted in vivo pharmacokinetic studies with one week intervals,6 Beagle dogs were dividied into two groups randomly. A group of dogs were administered pulsatile release tablets and another group dogs were administered tablets in single dose. The data were processed by PKSolver V2.0. According to the principle of minimum AIC, the pharmacokinetic parameters of the two preparations in Beagle dogs were determined by one-compartment model. The relative bioavailability of trimetazidine hydrochloride pulsatile release tablets was 96.95%.The results of variance analysis showed that the two formulations bioequivalent by statistically analyzed. Non-parametric test showed a significant difference (P< 0.05) in Tmax between the two formulations. The lag time of trimetazidine hydrochloride pulsatile release tablets in vivo was about 4 h, which can achieve the purpose of timing release. What's more, it was bioequivalent to the commercially available trimetazidine hydrochloride tablets.In the evaluation test of pulsatile release tablets in vitro and in vivo, Fa of absorption percentage in vivo was calculated using Wagner-Nelson method. The results showed that the correlation was good between release in vitro and absorption in vivo, and the regression equation was y=1.0232x+1.1021, r=0.9996.RESULTS:We prepared trimetazidine hydrochloride pulsatile release tablets by film coating technology according to the principle of time pharmacology and therapeutics. In the accelerated and Long-term tests between three batches, the results indicated that the formulations were stable and the homogeneities were good, which can be applied in industrialization production. Pharmacokinetic studies showed that there were good correlation between release in vitro and absorption in vivo. The release time lag in vivo was in accordence with that in vitro, which can achieve the purpose of pulse release. And it can reduce the concentration of drug in the night and reduce the drug resistance and side effects. Therefore, trimetazidine hydrochloride pulsatile tablets can be used to treat angina pectoris effectively, which have a high theoretical significance and value in clinical. |
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