美沙拉嗪肠溶缓释颗粒剂的药代动力学研究

目的评价美沙拉嗪肠溶缓释颗粒剂体内药物代谢动力学,通过与市售制剂的药动学特征比较,阐述美沙拉嗪肠溶缓释颗粒剂的临床前药代动力学特征,为新药评价提供可靠依据。方法以单剂量和多剂量2种方式口服给药,选取比格犬为受试对象,采用LC-MS/MS法测定血浆样品药物浓度。通过药动学参数估算和统计分析,评价美沙拉嗪肠溶缓释颗粒剂的体内吸收和消除过程、相对生物利用度、体内蓄积效应以及与市售制剂的药动学特征进行比较。结果美沙拉嗪肠溶缓释颗粒剂在比格犬体内单剂量口服(灌胃)给药后,美沙拉嗪缓释颗粒剂和美沙拉嗪肠溶片以美沙拉嗪表征的相对生物利用度分别为101.30%±20.20%、109.20%±30.80%。多剂量口服(灌胃)给药后,体内无蓄积效应。通过相对生物利用度和药代动力学参数的统计分析比较研究,提示美沙拉嗪肠溶缓释颗粒剂与市售的2种制剂无显著性差异。结论美沙拉嗪肠溶缓释颗粒剂吸收和消除过程基本呈线性动力学特征,多剂量给药后5 d左右达稳态、体内无蓄积,药动学参数与市售制剂无显著性差异。     

美沙拉秦生物等效评价标准的思考与建议

美沙拉秦是一种能透过黏膜吸收进入体循环的胃肠道局部作用药物，目前为治疗轻度、中度溃疡性结肠炎的一线用药，其血药时间曲线可能反映药物的局部作用。但因其相关上市品种剂型规格繁多，包括缓释胶囊、肠溶片剂、栓剂、灌肠液等，通常采用的药动学终点指标血药峰浓度(C_max)和血药浓度-时间曲线下面积(AUC)不一定能科学评价不同制剂美沙拉秦的质量一致性。本文综述了美国FDA、欧洲EMA对于美沙拉秦体内外生物等效性评价标准的制定和建议方案，并就我国公布的美沙拉秦参比制剂本身药学特征，总结发现我国公布的美沙拉秦参比制剂莎尔福并不适宜参照美国FDA所提出的美沙拉秦肠溶片生物等效性标准进行评价，并对此药提出了相应生物等效性评价指标选择的建议，以期为我国美沙拉秦仿制药的一致性评价工作提供参考。     

Absorption of ranolazine in a rat model of in-situ single-pass intestine perfusion 

目的：研究不同浓度雷诺嗪在大鼠肠段的吸收特征,并比较Beagle犬经口给予国外雷诺嗪缓释片(参比制剂)和国产雷诺嗪缓释片(受试制剂)的药动学。方法：以酚红为标示物,采用在体单向灌流法进行大鼠肠吸收研究,高效液相法测定灌流液中雷诺嗪和酚红的浓度并计算吸收参数。采用双交叉实验设计,6只Beagle犬分别经口给予受试制剂和参比制剂,高效液相法测定血药浓度,BAPP 3.0程序处理药动学参数。结果：10～40 mg•L-1的雷诺嗪在大鼠各肠段的表观通透系数(Papp)、吸收速率常数(Ka)的差异均无显著性意义(P>0.05)。Beagle犬经口给予单剂量国产雷诺嗪缓释片的相对生物利用度为(104.5±30.1)%。结论：在10～40 mg•L-1内雷诺嗪在大鼠肠道的吸收机制以被动吸收为主。国产和进口雷诺嗪缓释片在Beagle犬体内的药时曲线相似,2种缓释制剂均无突释现象。     

美沙拉嗪肠溶缓释片的制备与体外释放度考察

目的 制备美沙拉嗪肠溶缓释片,考察其体外释放.方法 以体外释放相似因子(f2)为主要评价指标,通过单因素处方筛选和正交试验设计得到最优处方,重现3批,比较自制美沙拉嗪肠溶缓释片与参比制剂的体外释放行为.结果 片芯中羧甲基纤维素钠(CMC 7HXF PH)用量为45 mg,羧甲淀粉钠(CMSNa)用量为35 mg;肠溶包...     

羧甲基玉米朊阿司匹林肠溶微丸的制备及体外释放度考察

目的:制备羧甲基玉米朊阿司匹林肠溶微丸,并考察其在大鼠体内的药动学特征。方法:以羧甲基玉米朊为肠溶材料,与阿司匹林按2∶1混合,加入乙醇作为黏合剂,采用挤压滚圆法制备羧甲基玉米朊阿司匹林肠溶微丸。以阿司匹林微丸作为参比制剂,考察受试制剂羧甲基玉米朊阿司匹林肠溶微丸灌胃给予15 mg/kg后在大鼠体内48 h内的药动学特征和4 h(前2 h在人工胃液中,后2 h在人工肠液中)内的体外释放度(n=5)。结果:所制羧甲基玉米朊阿司匹林肠溶微丸粒径为1 mm,规格为每丸3 mg。受试制剂与参比制剂的药动学特征均符合二室模型,主要药动学参数分别为t1/2β:(12.63±0.60)、(2.42±0.61)h,tmax:(11.07±1.10)、(3.41±0.84)h,cmax:(34.45±5.33)、(45.78±3.30)μg/ml,AUC0-∞:(613.52±41.14)、(550.69±34.44)μg·h/ml;与参比制剂比较,受试制剂的t1/2β、tmax、AUC0-∞均明显增加,cmax明显减小(P<0.05)。参比制剂2 h的累积释放度为87%,受试制剂2 h的累积释放度为1.7%、3 h的累积释放度达100%。结论:成功制得体外释放符合肠溶制剂要求的羧甲基玉米朊阿司匹林肠溶微丸。     

盐酸坦洛新肠溶缓释微丸的制备及其体内外评价

目的:制备盐酸坦洛新肠溶缓释微丸,并与参比制剂进行体内外一致性评价。方法:分别以乙基纤维素和羟丙甲纤维素为缓释包衣材料,以聚丙烯酸树脂为肠溶性包衣材料,采用流化床底喷包衣技术对载药微丸包衣,制备肠溶缓释微丸;考察释放度主要影响因素;采用多条释放曲线对比考察受试制剂与参比制剂体外一致性;双周期交叉试验设计,考察Beagle犬口服单剂量受试制剂与参比制剂后血浆中的药物浓度,评价受试制剂与参比制剂的体内一致性;考察受试制剂的体内外相关性。结果:确定了影响盐酸坦洛新释放的主要处方工艺因素;多条释放曲线测定结果表明,所制备的微丸与参比制剂体外一致性较好;Beagle犬体内药动学研究结果表明,受试制剂与参比制剂生物等效且体内外相关性良好。结论:成功制备了盐酸坦洛新肠溶缓释微丸,且与参比制剂体内外一致性良好。     

pH依赖—缓释型美沙拉秦结肠靶向小丸的制备与体外评价

以肠溶型和渗透型丙烯酸树脂为包衣材料制备ｐＨ依赖－缓释型美沙拉秦结肠靶向小丸,评价其体外释放特性。结果表明,包衣小丸在０．１ｍｏｌ／ＬＨＣｌ中２ｈ几乎不释放药物,在ｐＨ７．５缓冲液中具有较好的缓释作用。在模拟胃肠道各区段最高的和最低的ｐ变化的释放度试验中,均在对应小肠区段时开始缓慢释药。分别有４０％和７０％的药物进入结肠后释放。优于单独的肠溶或缓释制剂。     

玉米醇溶蛋白黏附控释片的制备及体外评价和体内药动学研究

目的：制备玉米醇溶蛋白黏附控释片,考察其体外黏附性能和释药行为以及体内药动学特性。方法：以玉米醇溶蛋白为骨架和黏附材料,5-氟尿嘧啶为模型药物,制备胃肠道生物黏附控释片,并将其与市售普通片剂和自制控释片进行体外黏附性能和释药行为以及大鼠体内药动学比较。结果：用玉米醇溶蛋白包衣的5-氟尿嘧啶黏附控释片具有良好的组织黏附性,体外释放在12小时之内符合零级释放,达到了控释目的,且与参比制剂相比,其在大鼠胃肠道的滞留时间更长,药物释放更平稳,缓释效应明显。结论：玉米醇溶蛋白对胃肠道黏膜具有良好的生物黏附性,将其用作包衣材料制各黏附控释片,可实现药物在胃肠道的缓控释。     

美沙拉嗪联合整肠生治疗溃疡性结肠炎的临床疗效观察

目的探讨美沙拉嗪联合整肠生治疗溃疡性结肠炎的临床疗效。方法 82例患者随机分为观察组与对照组,各41例,对照组口服美沙拉嗪缓释颗粒剂,观察组在对照组的基础上加服整肠生。比较两组患者临床疗效、不良反应,并进行统计学分析。结果观察组临床疗效明显优于对照组,两组痊愈人数、有效率比较差异具有统计学意义(P<0.05)。观察组不良反应发生率为14.3%;对照组不良反应发生率为28.6%,两组不良反应发生率比较差异具有显著性(P<0.05)。结论美沙拉嗪联合整肠生治疗溃疡性结肠炎疗效确切,不良反应少,值得临床推广和应用。     

2种罗格列酮钠制剂在犬体内的生物等效性研究

目的:比较罗格列酮钠肠溶制剂与罗格列酮钠普通制剂在犬体内的药动学特征及其生物等效性。方法:将6只犬均分为2组,分别单次灌服罗格列酮钠肠溶胶囊或罗格列酮钠普通胶囊4mg,于给药前及给药后450min内后腿静脉取血,给药7d后,相同剂量自身交叉给药,于上述相同时间点取血,用高效液相色谱法测定血浆中罗格列酮浓度;经DAS2.0软件处理,计算药动学参数。结果:在相同剂量下,罗格列酮钠肠溶胶囊与其普通胶囊的药动学参数分别为AUC0～∞:(119.662±8.451)、(118.493±15.325)mg.min.L-1,t1/2Ka:(101.548±6.526)、(39.702±26.293)min,cmax:(0.359±0.035)、(0.807±0.208)mg.L-1;与普通胶囊比较,肠溶胶囊的AUC0～∞无显著性差异,t1/2Ka明显延长、cmax明显降低(P<0.05或P<0.01)。结论:与普通胶囊比较,罗格列酮钠肠溶制剂与其生物等效且具有明显的缓释特征。     

Citric acid as excipient in multiple-unit enteric-coated tablets for targeting drugs on the colon

Delivery of drugs to the large bowel has been extensively investigated during the last decade. The aim of this study was to investigate whether enteric-coated tablets could be made from enteric-coated matrix granules and drug release targeted to the colon. Whether in vitro drug release rate and in vivo absorption could be delayed by adding citric acid to the granules and/or to the tablet matrix was also studied. Ibuprofen was used as model drug because it is absorbed throughout the gastrointestinal tract. Eudragit S and Aqoat AS-HF were used as enteric polymers. Drug release rates were studied at different pH levels and drug absorption was studied in bioavailability tests. The conclusion was that citric acid retarded in vitro drug release when used in multiple-unit tablets. In vivo absorption of ibuprofen was markedly delayed when citric acid was included in both granules and tablet matrix. Further studies are needed to determine the optimal amount of citric acid in formulations.     

Determination of the population pharmacokinetic parameters of sustained-release and enteric-coated oral formulations,and the suppository formulation of diclofenac sodium by simultaneous data fitting using NONMEM

Data from sustained-release and enteric-coated oral formulations, and the suppository formulation of diclofenac sodium are fitted simultaneously using NONMEM® and the general linear model, ADVAN 5. Absorption and disposition parameters, serum levels, and absorption profiles were determined. The in vivo absorption profiles were determined using the program TOPFIT®. The in vivo absorption for the sustained-release formulation is slow first order and follows a flip-flop model since disposition rate constants are greater than absorption rate constants. Absorption from the enteric-coated form is essentially complete (≥95%) at about 7.5 h, while it is 95% complete at 24 h from the sustained-release formulation. This suggests likely absorption from the colon in the case of the sustained-release formulation since absorption is only 75% complete during the first 10 h. The sustained-release relative bioavailability is 90–99%. Absorption from the suppository is essentially complete at about 4.5 h. However, the relative bioavailability of the suppository formulation is low (55%), since defecation may remove the drug from the absorption site before complete absorption. © 1998 John Wiley & Sons, Ltd.     

Comparison of gastroretentive microspheres and sustained-release preparations using theophylline pharmacokinetics

The objective of this study was to use the pharmacokinetics of theophylline to compare various gastroretentive microspheres. Three types of theophylline microspheres prepared from a hydrophobic dextran derivative were characterized in terms of drug release in-vitro and floating and mucoadhesive properties. Theophylline pharmacokinetic studies were conducted in Beagle dogs, comparing bulk powder, commercial sustained-release granules (Theodur), sustained-release microspheres, floatable microspheres and mucoadhesive microspheres. Theodur and sustained-release microspheres resulted in a lower maximum concentration (Cmax) (P < 0.01) and larger values for mean residence time (MRT) (P < 0.05) than bulk powder, whereas area under the concentraion-time curve (AUC) were lower. The floatable microspheres showed a larger value for MRT than bulk powder (P < 0.01), and a larger AUC than Theodur (P < 0.05). The pharmacokinetic parameters of the mucoadhesive microspheres indicated an increase in AUC without decreasing the rate of bioavailability. Overall, the gastroretentive microspheres improved the extent of bioavailability of theophylline, which is absorbable from the entire gastrointestinal tract. The mucoadhesive microsphere showed a prolonged serum drug level, indicating a superior sustained-release delivery system for theophylline.     

New Evaluation Method for in Vitro/in Vivo Correlation of Enteric-Coated Multiple Unit Dosage Forms

Purpose. To establish the evaluating method for drug dissolution profiles in the gastrointestinal (GI) tract based on in vitro data for the enteric-coated multiple unit. Methods. Dissolution profile in the GI tract was calculated by the convolution procedure using an in vitro dissolution profile as a weighting function, and the gastric-emptying (GE) process as an input function (GE-convolution method). A computer program, GECONV, was developed for numerical execution of the convolution integral. Results. The in vivo dissolution profile of enteric-coated aspirin granules estimated by GE-convolution was in good agreement with the in vivo cumulative absorption profile calculated by the Wagner-Nelson method using the plasma concentration data after oral administration to healthy subjects. The in vitro/in vivo correlation improved markedly by taking the GE process into consideration. Conclusions. These findings indicated that this convolution method is useful for estimating the in vivo dissolution profile of drugs, when they are administered in an enteric-coated multiple unit type dosage form, because the gastric emptying process is a determinant process for the in vivo drug dissolution.     

Combined scintigraphic and pharmacokinetic investigation of enteric-coated mesalazine micropellets in healthy subjects

BACKGROUND: There is a growing clinical trend to increase the daily dose of mesalazine, which leads to significant compliance issues associated with multiple dosings of current preparations. AIM: To examine the gastrointestinal performance and systemic exposure of a 1.5 g sachet (micropellets) mesalazine formulation, compared with three enteric-coated tablets (500 mg each, Claversal). METHODS: A randomized, two-way, cross-over pharmacoscintigraphic (scintigraphy plus pharmacokinetics) study and a two-way, cross-over, pharmacokinetic-only study were performed in 24 healthy volunteers (12 subjects per investigation). RESULTS: The relative bioavailability of mesalazine was 92% comparing micropellets with Claversal tablets, and the cumulative urine excretion was c. 26% for both preparations, suggesting comparable systemic exposure for the two types of preparation. In the majority of subjects, drug release from the micropellet formulation occurred predominantly in the terminal ileum and ascending colon. The Claversal tablets disintegrated in comparable intestinal sites, albeit at slightly later time points than the micropellets, principally due to slower gastric emptying for the single-unit formulation. CONCLUSION: The 1.5 g micropellet formulation offers comparable delivery properties to the marketed tablets, but with greater convenience of dosing.     

Pharmacokinetic Analysis of an Oral Sustained-Release Diltiazem Preparation Using Multifraction Absorption Models

Application of multifraction absorption models to pharmacokinetic analysis of an oral sustained-release diltiazem preparation (HER-SR) was investigated. The plasma diltiazem concentrations after oral administration of the HER-SR preparation were analyzed using both the two-fraction absorption model and the two-step discontinuous absorption model. The two-fraction absorption model was suitable for the pharmacokinetic analysis of the HER-SR preparation, whereas the two-step discontinuous absorption model is often unsuitable for the analysis of sustained-release preparations which disintegrate into fractions with different release characteristics in the gastrointestinal tract. The two-step discontinuous absorption model is usually not applicable to plasma concentration data when the first peak is sharp. MFA-MULTI(V) was shown to be useful for the prediction of the bioavailability in each fraction of HER-SR. It was further demonstrated that a two-fraction absorption model is useful for the comparison of in vitro and in vivo release profiles or evaluating the influence of food on the absorption behavior of HER-SR. In addition, the application of a two-fraction absorption model to population pharmacokinetics of HER-SR was investigated.     

Bioavailability of phenylbutazone from a new enteric-coated formulation with superior dissolution characteristics

The bioavailability of an improved formulation of enteric-coated phenylbutazone with faster dissolution, more consistent in vitro rate of drug release and improved stability was compared in 8 normal subjects at doses of 100 and 200 mg with commercially available Butacote®. Phenylbutazone was more rapidly absorbed from the new formulation and higher plasma concentrations were achieved at shorter intervals after dosing. Drug elimination rate was unaffected by reformulation and despite faster absorption the total amounts of drug reaching the circulation from the new and commercial products were similar. It was concluded that replacing Butacote® by the new formulation would provide the same therapeutic benefit.     

Extensive Absorption of 2′,3′-Dideoxyinosine by Intratracheal Administration in Rats

Purpose. To evaluate the intratracheal route of administration as an alternative to oral administration for 2,3-dideoxyinosine (ddI). Methods. A ddI dose (40 mg/kg/300 µl or 6.5 mg/kg/50 µl) was instilled into the trachea in female Fisher rats and an intravenous tracer dose (9 µg/kg) of ³H-ddI was administered concomitantly to determine the drug clearance. Plasma concentrations were analyzed for the rate and extent of absorption. Results. ddI was rapidly absorbed from the lungs, with a bioavailability of 63% at 40 mg/kg and 101% at 6.5 mg/kg. By comparison, our previous data showed an oral bioavailability of about 15% (Pharm Res., 9:822, 1992). The distribution of a dye solution instilled intratracheally showed that a fraction of the 300 µL dose spilled over to the gastrointestinal tract, where the entire 50 µL dose was retained in the lungs. The different distribution of the two doses/volumes likely contributed to the different bioavailability, with a fraction of the higher dose/volume degraded in the gastrointestinal tract after the spillover. Absorption of ddI from the airspace of the lung was biexponential, suggesting two absorption processes. Conclusions. These data indicate significantly higher and less variable bioavailability of ddI by the intratracheal route of delivery compared to the oral route. Furthermore, the complete bioavailability at the lower dose/volume indicates no significant pulmonary first pass elimination for ddI.     

Oral bioavailability of omeprazole before and after chronic therapy in patients with duodenal ulcer.

1. This study investigated the mechanism of the increase in oral bioavailability of omeprazole during repeated oral dosing. Eight patients with duodenal ulcer received an i.v. dose of omeprazole before and after a 4-week course of oral omeprazole, 20 mg daily, given as enteric-coated granules. 2. AUCoral and oral bioavailability (F) increased during omeprazole treatment by 50% (P less than 0.01) and 35% (P less than 0.05), respectively. 3. There was no change in the systemic clearance of omeprazole after i.v. dosage following the course of treatment. 4. We conclude that the increased omeprazole AUC observed on repeated administration of enteric-coated granules is due to increased systemic availability rather than decreased systemic elimination. The increased availability appears to be due to increased gastrointestinal absorption rather than decreased first-pass hepatic extraction.     

Population pharmacokinetics of orally administered paclitaxel formulated in Cremophor EL

AIM: The vehicle Cremophor EL (CrEL) has been shown to impair the absorption of paclitaxel by micellar entrapment of the drug in the gastrointestinal tract. The goal of this study was to develop a semimechanistic population pharmacokinetic model to study the influence of CrEL on the oral absorption of paclitaxel. METHOD: Paclitaxel plasma-concentration time profiles were available from 55 patients (M:F, 17 : 38; total 67 courses; 797 samples), receiving paclitaxel orally once or twice daily (dose range 60-360 mg m(-2)) together with 12-15 mg kg(-1) cyclosporin A. A population pharmacokinetic model was developed using the nonlinear mixed effect modelling program NONMEM. RESULTS: After absorption, paclitaxel pharmacokinetics were best described using a two-compartment model with linear distribution from the central compartment into a peripheral compartment and first-order elimination. Paclitaxel in the gastrointestinal tract was modelled as free fraction or bound to CrEL, with only the free fraction available for absorption into the central compartment. The equilibrium between free and bound paclitaxel was influenced by the concentration of CrEL present in the gastrointestinal tract. The concentration of CrEL in the gastrointestinal tract decreased with time with a first order rate constant of 1.73 h(-1). The bioavailability of paclitaxel was independent of the dose and of CrEL. Estimated apparent paclitaxel clearance and volume of distribution were 127 l h(-1) and 409 l, respectively. Large interpatient variability was observed. Covariate analysis did not reveal significant relationships with any of the pharmacokinetic parameters. CONCLUSION: A pharmacokinetic model was developed that described the pharmacokinetics of orally administered paclitaxel. CrEL strongly influenced paclitaxel absorption from the gastrointestinal tract resulting in time-dependent but no significant dose-dependent absorption over the examined dose range studied.