Prediction of the bioequivalence of different crystal forms of rifampicin based on physiologically based pharmacokinetic model / 中国药科大学学报

@#The physiologically based pharmacokinetic (PBPK) modeling strategy was adopted to predict the pharmacokinetic behavior of crystal forms I and II of rifampicin in humans, which was used to determine whether the two were bioequivalent.After conducting studies in vitro of the two crystal forms, a rat PBPK model was established based on the pharmacokinetic data of intravenous administration in rats.The model was optimized by the pharmacokinetic data of oral administration in rats.Species were extrapolated to healthy humans, and the extrapolation model was used to predict such pharmacokinetic behaviors as the drug-time curve, absorption site, and absorption amount of the two crystal forms of rifampicin in healthy humans.The prediction results of the healthy human model showed that the cmax of form I and form II rifampicin were 8.42 and 10.35 μg/mL, tmax were 0.40 and 0.32 h,and AUC0-t were both 62.90 μg·h/mL.According to the prediction results of absorption, neither crystal form I nor crystal form II rifampicin was absorbed in the stomach, yet both were completely absorbed in the intestinal tract, with both the absorption site and the absorption amount were basically the same.The pharmacokinetic parameters of both crystal forms I and II of rifampicin were very close, which could indicate bioequivalence.

Pharmacokinetic Study of Letrozole Polymorphs in Rats / 医药导报

Objective To study the gastrointestinal absorption process of three letrozole polymorphs in rats, and evaluate the different pharmacokinetics parameters of different polymorphs. Methods A total of 18 SD rats were given the different letrozole polymorphs. Then the high-performance liquid chromatographic method was used for the determination of plasma concentration of letrozole in these SD rats.Finally the pharmacokinetic parameters among the different polymorphs were calculated. Results Cmax of letrozole crystal form I, crystal form II and crystal form III were (9.247± 4.612) ,(23.387± 9.049) and (15.682±1.589) mg·L-1, respectively, and AUC0→t were(198.115±47.014) ,(476.641±125.467) and (271.817±41.068) mg·L-1·h,respectively. Conclusion The different crystal forms of letrozole result in different plasma concentration in SD rats. Crystal form II may be its preponderant polymorphs which deserves further research and development.

Effects ofⅠ,ⅡCrystal and Amorphous Forms of Lercanidipine Hydrochloride on the Preparation / 中国药房

OBJECTIVE:To study the effects of Ⅰ,Ⅱ crystal and amorphous forms of lercanidipine hydrochloride on the preparation,and provide theoretical basis for its development and consistency evaluation. METHODS:X-ray powder diffraction (XRD),infrared spectrophotometry(IR)and differential scanning calorimetry(DSC)were adopted to identify the 3 crystal forms of lercanidipine hydrochloride. XRD was used to compare the effects of crushing,grinding,pressing technology,wetting granula-tion,adhesive solvents(water,ethanol)and drying temperature(50,60,70℃)on stability of 3 crystal forms of lercanidipine hy-drochloride;the dissolution in vitro in water,hydrochloride,pH 4.5 acetate buffer,pH 6.8 phosphate buffer were compared among 3 crystal forms of Lercanidipine hydrochloride tablet. RESULTS:XRD showed both Ⅰ,Ⅱ crystal forms had characteristic diffrac-tion peak with inconsistent 2 θ values,amorphous had no characteristic diffraction peak;IR showed 3 crystal forms had different absorption intensity and absorption peak number;DSC showed Ⅰ,Ⅱ crystal forms had obvious endothermic peak in 194.6 ℃, 207.3 ℃,respectively,amorphous had obvious endothermic peak in 86.1 ℃ and exothermic peak in 299.8 ℃. Crushing,grinding, pressing and drying temperature had no effects on the stability of 3 crystal forms;water had no effect on the stability of crystal in wetting granulation,ethanol may cause the change of Ⅰcrystal form. Except for the comparison between Ⅰ,Ⅱ crystal forms in hydrochloride (f2=68),the dissolution f2 of 3 crystal forms in 4 kinds of medium were lower than 50. CONCLUSIONS:XRD, IR,DSC methods can identify the 3 crystal forms of Lercanidipine hydrochloride tablet. When preparing lercanidipine hydrochlo-ride by Ⅰcrystal form,wetting granulation should avoid using ethanol as a adhesive solvent,instead of water. Different crystal forms can affect the dissolution in vitro of prepared Lercanidipine hydrochloride tablet.

Bioequivalence study of two crystal forms of rifampicin in isoniazid and rifampicin tablets / 中国药学杂志

OBJECTIVE: To evaluate the pharmacokinetic properties and bioequivalence of two crystal forms of rifampicin. METHODS: Drawing the dissolution curves of reference and test medicines in different solutions, and calculated the value of f2. Twenty-nine healthy male volunteers were randomly administered in a crossover single 300 mg dose of reference and test medicines. Determining the concentration of rifampicin in plasma by HPLC-MS, and analyzed the relative bioavailability and bioequivalence of tablets using SAS program. RESULTS: The values of f2 were more than 50.The pharmacokinetic properties of reference and test tablets were as follows: AUC0→t: (28476±8 050) vs (28120±6916) ng·mL·h-1, ρmax: (5552±1554) vs (5911±1700)ng·mL-1, t2: (2.0±1.0) vs (1.8±1.0) h, t1/2:(2.8±0.5)vs(2.8±0.5) h. 90% CI of AUC and ρmax of test medicine were 96.2%-106.4% and 98.6%-115.3%, respectively. And there were no significant difference of the tmax of rifampicin between the two medicines (P>0.05). CONCLUSION: The results indicate that the two medicines made from rifampicin two crystal forms are bioequivalent completely.

Effect of age on the pharmacokinetics of polymorphic nimodipine in rats after oral administration

The previous investigation has proved that their existed pharmacokinetic difference between the different crystal forms of the polymorphic drugs after oral administration. However, no systemic investigations have been made on the change of this pharmacokinetic difference, resulted either from the physiological or from the pathological factors. In this paper, we used polymorphic nimodipine (Nim) as a model drug and investigated the effect of age difference (2- and 9-month old) on the pharmacokinetics after oral delivery in rats. As the results shown, for L-form of Nim (L-Nim), the AUCin 2-month-old rats was 343.68±47.15 ng·h/mL, which is 23.36% higher than that in 9-month-old rats. For H-form of Nim (H-Nim), the AUCin 2-month-old rats was 140.91±19.47 ng·h/mL, which is 54.64% higher than that in 9-month-old rats. The AUCratio between H-Nim and L-Nim was 2.44 in 2-month-old rats and 3.06 in 9-month-old rats. Since age difference could result in unparallelled change of the absorption and bioavailability of the polymorphic drugs, the results in this experiment are of value for further investigation of crystal form selection in clinical trials and rational clinical application of the polymorphic drugs.

Crystal form identification of dasatinib in tablets / 中国药科大学学报

The aim of this study was to establish the methods to identify crystal form of dasatinib in tablets.X-ray powder diffraction(XRPD)and solid-state nuclear magnetic resonance(ssNMR)were used to analyze the crystal form of dasatinib in Sprycel? tablets and Yinishu? tablets.The results showed that monohydrate and anhydrate were identified in Sprycel? and Yinishu? tablets respectively;with no detectable anhydrate in Sprycel? tablets and no detectable monohydrate in Yinishu? tablets.The results of XRPD and ssNMR were consistent;and could be both applied in the crystal form identification of dasatinib in tablets.

Thermostability of fluconazole with different crystal forms / 中国药学杂志

OBJECTIVE: To investigate the thermostability of four crystal forms of fluconazole. METHODS: The thermostability of fluconazole was analyzed using XRD, DSC and TGA, and the structural characteristics of the crystal forms and crystalline transformation were determined using XRD with in-situ high temperature accessories. RESULTS: The crystal form I and II had good at thermostability, and the crystal structure of form III changed at about 40°C. The monohydrate transformed to form II at about 70°. CONCLUSION: The different crystal forms of fluconazole have distinct thermostability. The result of this study would provide a comprehensive reference for the quality evaluation of fluconazole.