Modeling in Frequency Domain Used for Assessment of In Vivo Dissolution Profile

Purpose. To present a model-dependent approach for the assessment of the in vivo drug dissolution profile based on in vitrodata for the multiple unit dosage form, as an alternative to the numerical method proposed in the study by Hayashi et al, Pharm. Res. 12:1333–1337 (1995). Methods. The data for aspirin granules administered to healthy subjects obtained in the above mentioned study were re-evaluated. The subject dissolution system was considered to consist of two subsystems connected in series, i.e. the subsystem describing the gastric-emptying process and the subsystem describing the intestinal dissolution process. The frequency response method was used to model the subject dissolution system. Results. The model in vivodissolution profile of aspirin, assessed as the integral of the model weighting function of the subject dissolution system, was in agreement with the in vivo cumulative absorption profile calculated by the Wagner-Nelson method. Conclusions. Comparison of dynamic properties of the subject dissolution system with the subsystem describing the gastric-emptying process yielded quantitative confirmation of the decisive role of the gastric-emptying process in the in vivodrug dissolution after administration in the multi unit dosage form.     

BIOEQUIVALENCE BETWEEN rhGH FOR RECONSTITUTION AND READY-TO-USE rhGH IN TWO LIQUID FORMULATIONS

Objective To evaluate the bioequivalence between recombinant human growth hormone （rhGH） for reconstitution, and two dosages of liquid formulation of rhGH [ （151U） 5mg or （301U） lOmg per 3ml ]. Methods The study drugs were tested in a randomized, single-blind and three-period crossover studies in 24 healthy male subjects. The three drugs were administered by subcutaneous injection at a dose of O. 21U/kg body weight. A continuous somatostatin infusion was given in order to suppress the secretion of endogenous GH. The ve- nous blood samples were drawn at different time points to test the serum concentration of GH. The pharmacokinetic parameters were analyzed by statistical methods. Results 90% confidence intervals （CI） of AUC0-24h among three products were all within 80% - 125% interval （ 103. 4% - 116. 5%, 105. 7% - 119. 6% and 91.9% - 103. 7%, respectively）, and the Cls of C,~ among three products were all within 70% - 143% interval （91.9% - 114. 0%, 103. 7% -127. 2% and 81.6% -97. 4%, respectively）. There was no statisitical difference of tmax among all the three products. Conclusion These data demonstrate that there is bioequivalence between rhGH for reconstitution and two liquid formulations of rhGH.     

阿比朵尔片剂与胶囊剂的人体生物等效性比较

 目的评价阿比朵尔片与参比制剂(阿比朵尔胶囊)是否等效。方法20名男性健康受试者随机分为2组,交叉口服受试制剂(阿比朵尔片)和参比制剂各200 mg后,以高效液相色谱法测定血浆中药物浓度。所得数据用3P87统计软件进行处理。结果阿比朵尔受试制剂和参比制剂的t_max分别为(1.08±0.61)和(1.63±1.06)h;ρ_max分别为(408.5±167.4)和(417.8±240.7)μg·L^-1;t_1/2分别为(11.77±5.01)和(10.55±4.01)h;用梯形法计算,AUC_0-48分别为(2 641.2±1 024.0)和(2 725.8±1 181.0)μg·h·L^-1;AUC_0-∞分别为(2 751.5±1 197.6)和(2 857.4±1 311.3)μg·h·L^-1。以AUC_0-48计算,盐酸阿比朵尔片的相对生物利用度平均为(96.9±42.3)%。结论2种制剂具有生物等效性。     

Receptor binding assays in analysing the bioavailability and pharmacodynamic bioequivalence of active drug moieties

The bioavailability and pharmacodynamic bioequivalence of a conventional and an experimental sustained-release formulation of 100 mg metoprolol tartrate were studied in a randomised cross-over study in seven healthy volunteers by assessing over 24 h the plasma kinetics of R,S-metoprolol, its ₁-adrenoceptor binding component, and by determining the extent to which the active drug moiety in plasma occupied rabbit lung ₁-and rat reticulocyte ₂-adrenoceptors.The formulations differed markedly in their kinetic characteristics: the peak plasma concentration (C_max) of R,S-metoprolol after administration of the conventional formulation was 140 ng·ml^–1, (n=7) and it was approximately one-third of that after the sustained-release formulation, 49 ng·ml^–1, (n=6); the AUC_{0–24 h}-values for the formulations were 700 and 310 ng·h·ml^–1, respectively. The C_max for the ₁-adrenoceptor binding component of metoprolol was 180 ng·ml^–1 (n=7) after administration of the conventional, and 74 ng·ml^–1 after administration of the sustained-release formulation. The corresponding AUC_{0–24 h}-values for the receptor binding component were 920 and 470 ng·h·ml^–1 (n=7).Thus, the kinetic differences between R,S-metoprolol and the ₁-receptor binding component were considerable and they were affected by the type of formulation. In general, after administration of the sustained-release formulation, the percentage ₁- and ₂-adrenoceptor occupancy of metoprolol in plasma was 5–15% less than after administration of the conventional formulation. At 0.5–1.5 h after drug intake the average ₁-adrenoceptor occupancy of the conventional formulation varied between 80–90% and that of the sustained release formulation between 20–76%. At these times the differences in receptor occupancy were significant; at 0.5–2 h after drug intake the average ₂-adrenoceptor occupancy of the conventional formulation varied from 20–30%, and that of the sustained-release formulation was 2–17%. At other times the difference in receptor occupancy between the formulations was not significant.The results demonstrate that plasma concentration-kinetics were more discriminating than -adrenoceptor-binding in analysing bioequivalence. It was possible to determine the bioavailability of the active ingredient of metoprolol and to study pharmacodynamic bioequivalence by using receptor binding assays.     

Use of Stable Isotopes for Evaluation of Drug Delivery Systems: Comparison of Ibuprofen Release in Vivo and in Vitro from Two Biphasic Release Formulations Utilizing Different Rate-Controlling Polymers

Certain delivery systems are intended to release the active ingredient in different phases to obtain the desired therapeutic effect. For these formulations, such as a bilayer tablet, it is desirable to distinguish and measure the release of drug from the different phases simultaneously. Mass spectrometric methods were developed to measure three ibuprofen isotopomers in serum and two in dissolution fluid. The analytical methods were linear (r 0.992) over the concentration range of interest and recovery was greater than 99.2% for all isotopomers. Coadministration of [²H₀]ibuprofen, [²H₄]ibuprofen, and [²H₇]ibuprofen to male beagles demonstrated that the isotopomers were bioequivalent and verified the absence of any kinetic isotope effect due to deuterium incorporation (p = 0.286). These methods were then used to evaluate a bilayer tablet formulation composed of an immediate release layer of 100 mg [²H₄]ibuprofen and a sustained release layer with a drug load of 300 mg [²H₀]ibuprofen. Two different rate-controlling polymer matrices that provided similar in vitro dissolution profiles were compared in the sustained release phase, while the immediate release formulation remained the same. In male beagles, the HPMC matrix delivered a significantly greater amount of ibuprofen (p < 0.05). The AUC was threefold greater for HPMC (1067 ± 437 nmole * h/ml) versus EUDRAGIT^® (320 ± 51), and C_max was nearly four times greater (145 ± 62.1 nmole/ml for HPMC versus 37.9 ± 14.4 for EUDRAGIT^®). Although T_max for HPMC (3.4 ± 1.9 h) lagged behind EUDRAGIT^® (2.0 ± 0.82 h), the difference was not significant (p > 0.05). The immediate release layer was absorbed to the same extent as an oral solution (containing [²H₇]ibuprofen) that was administered concomitantly with the bilayer tablet. Using the stable isotope markers also demonstrated that the release rates of the two layers were independent of each other, both in vivo and in vitro. Stable isotope techniques are a useful tool in the development of biphasic release formulations since they can be used to determine proper drug load of each phase as well as the appropriate rate of release.     

An Approach for Widening the Bioequivalence Acceptance Limits in the Case of Highly Variable Drugs

Purpose. Highly variable drugs pose a problem in bioequivalence assessment because they often fail to meet current regulatory acceptance criteria for average bioequivalence (80–125%). This paper examines alternative approaches to establishing bioequivalence. Methods. Suggested solutions have included alternate study designs, e.g., replicate and multiple dose studies, reducing the level of the confidence interval, and widening the acceptance limits. We focus on the latter approach. Results. A rationale is presented for defining wider acceptance limits for highly variable drugs. Two previously described methods are evaluated, and a new method having more desirable properties is proposed. Conclusions. We challenge the one size fits all current definition of bioequivalence acceptance limits for highly variable drugs, proposing alternative limits or goal posts which vary in accordance with the intrasubject variability of the reference product.     

头孢克洛缓释片在健康人体的药代动力学及生物等效性

目的 研究头孢克洛两种缓释片在健康志愿者体内的药代动力学和相对生物利用度。方法 20名健康男性受试者随机交叉单剂量及多剂量口服受试制剂375mg和参比制剂375mg,用液相色谱一串联质谱法测定给药后不同时刻的血浆浓度,求得主要药代动力学参数。结果 单剂量口服获得的主要药动学参数,t_(max)分别为2.23±0.64和2.05±0.56 h,C_(max)分别为2.54±0.89和2.38±0.65 mg·L~(-1),AUC_(0-t)分别为7.38±1.66和7.09±1.71 mg·h.L~(-1),t_(1/2)分别为1.08±0.12和1.07±0.13h,F为(105.0±11.2)％。多剂量口服获得的主要药动学参数AUC_(ss)分别为7.22±1.37和7.02±1.53mg·h·L~(-1),C_(max)分别为2.61±0.61和2.34±0.55 mg·L~(-1),C_(min)分别为3.48±1.33和3.65±1.23 μg·L~(-1),C_(av)分别为602±114和585±128μg·L~(-1),DF分别为4.3±0.7和4.0±0.6,F为(105.5±19.9)％。统计学结果显示,两种制剂的药动学参数无显著性差异,符合生物等效性标准。结论 头孢克洛两种缓释片均具有较好的缓释特征,两种制剂生物等效。     

氢溴酸右美沙芬片健康人体生物等效性

目的 :研究氢溴酸右美沙芬片在健康人体的药动学及相对生物利用度。方法 :8名健康受试者单剂量随机交叉口服氢溴酸右美沙芬片参比制剂和被试制剂 6 0mg ,采用HPLC法测定用药后不同时间的血药浓度。结果 :2种制剂的体内过程均符合一房室开放模型 ,参比制剂和被试制剂的tmax分别为 (2 72± 0 2 1)h和 (2 74± 0 19)h ,cmax分别为 (5 5 1± 0 4 4) μg·L-1和(5 5 8± 0 2 7) μg·L-1,AUC分别为 (4 5 3± 2 9) μg·h·L-1和 (4 5 7± 3 0 ) μg·h·L-1,被试制剂的相对生物利用度为 (10 1±5 9) %。结论 :2种制剂具有生物等效性。     

多西环素肠溶微粒胶囊与片剂的人体生物等效性

目的 :研究多西环素肠溶微粒胶囊和多西环素片的人体生物等效性与药动学。方法 :2 0名男性健康志愿者随机分 2组 ,按双周期交叉口服单剂量 2 0 0mg多西环素的 2种制剂 ,分别于服药前及服药后 0 5 ,1,1 5 ,2 ,2 5 ,3,4,6 ,8,12 ,2 4,48,72h取血样 ,以HPLC法测定血浆中多西环素浓度 ,计算 2种制剂相对生物利用度参数 ,并评价其生物等效性。结果 :口服受试制剂多西环素肠溶微粒胶囊和参比制剂多西环素片的药动学参数 :cmax分别为 (3 6 5± 0 81) μg·mL-1和 (3 6 5± 0 73) μg·mL-1,tmax分别为 (2 5± 0 3)h和 (2 2± 0 7)h ,T1/ 2 (消除半衰期 )分别为 (2 1 4 8± 3 2 0 )h和 (2 1 85± 3 11)h ,AUC0→ 72 分别为 (72 18±2 2 6 8) μg·h·mL-1和 (72 0 6± 2 1 0 8) μg·h·mL-1,AUC0→∞ 分别为 (81 4 4± 2 4 94) μg·h·mL-1和 (81 82± 2 3 19) μg·h·mL-1,多西环素肠溶微粒胶囊相对生物利用度为 (10 1 9± 2 5 2 ) %,对参数cmax,AUC0→ 72 先进行方差分析 ,再进行双单侧t检验 ,表明 2种制剂的参数生物等效 ,tmax经非参数检验表明无统计学差异。结论 :多西环素肠溶微胶囊和多西环素片具有生物等效性。     

尼美舒利栓药代动力学及相对生物利用度研究

目的　以市售的尼美舒利普通片为参比制剂 ,评价自制尼美舒利直肠栓的生物利用度和生物等效性。方法　采用随机交叉分组实验设计 ,5只新西兰家兔分别给予剂量 5 0 mg.kg- 1 的尼美舒利栓和普通片剂 ,栓剂直肠给药 ,片剂口服 ;按设计采集 2 4h内动态血标本 ;以 HPLC法测定血浆药物浓度 ;以二室模型计算两种制剂在动物体内的药动学参数和相对生物利用度。结果　参比制剂和受试制剂的 Tmax 分别为 ( 6.96± 1 .69) h和( 2 .0 3± 1 .0 7) h,Cmax 分别为 ( 65 .5 1± 2 8.0 9) mg.L- 1和 ( 65 .99± 1 2 .1 3 ) mg.L- 1 ,AUC0 - inf 分别为 ( 5 1 9.3 4±1 5 1 .0 5 ) mg.h.L- 1和 ( 4 40 .1 2± 72 .89) mg.h.L- 1 ,t1 / 2α分别为 ( 0 .63± 0 .1 3 ) h和 ( 2 .2 9± 0 .82 ) h,t1 / 2β分别为( 1 .72± 0 .95 ) h和 ( 1 .76± 0 .2 1 ) h,MRT分别为 ( 9.0 0± 1 .1 6) h和 ( 6.2 4± 0 .62 ) h,滞后时间分别为 ( 5 .42±1 .63 ) h和 ( 0 .0 7± 0 .0 9) h,以市售 NIM普通片为参比制剂 ,NIM直肠栓的相对生物利用度为 84.75 %。结论　统计结果显示 ,各主要药动学参数均有显著性差异。尼美舒利栓具有明显的速释特征 ,与尼美舒利普通片生物不等效。