New bioequivalence studies: individual bioequivalence and population bioequivalence

The bioequivalence study which is currently conducted in different countries is the so-called average bioequivalence approach; this approach has been indicated to be insufficient for assessing switchability between two formulations (i.e., from the reference formulation to the test formulation). In the U.S., therefore, the population bioequivalence approach and the individual bioequivalence approach were recently proposed as the studies which would replace the current average bioequivalence approach. The average bioequivalence approach compares only the mean parameters of the test and reference formulations in the subject groups which received them. In contrast, the population bioequivalence approach guarantees prescribability by assessing the total variances of bioavailability values of the test and reference formulations in addition to the average bioequivalence. The individual bioequivalence approach guarantees switchability from the reference formulation to the test formulation by assessing the intrasubject variance and subject-by-formulation interaction in addition to the average bioequivalence. We introduce the individual bioequivalence approach and the population bioequivalence approach in comparison with the current average bioequivalence approach and have discussed the characteristics and issues of each of these three bioequivalence approaches.     

Bioequivalence study of two fluoxetine capsule formulations in healthy Middle Eastern volunteers

OBJECTIVE: To assess the bioequivalence of two fluoxetine hydrochloride capsule (20 mg) formulations (Fluoxicare capsule from Pharmacare Ltd., Chemicals and Cosmetics, Ramallah, Palestine, as test formulation, and Prozac from Eli Lilly Ltd., Basingstoke, UK, as reference formulation). DESIGN AND METHODS: The study was conducted open with a randomized 2-period crossover design and a 6-week washout period. Participants were 24 healthy male volunteers aged 18-28 years, divided into 2 groups of 12 subjects. One group was given the originator drug (reference formulation), and the other was given the test formulation. Blood samples were obtained at baseline and at 14 time points during the interval 0-96 hours after drug administration. The concentrations of the samples were assayed spectrophotometrically at 220 nm using a Shimadzu 160 A UV-visible spectrometer. We calculated the plasma concentration-time curve (AUC), maximum plasma concentration (Cmax), and time of maximum plasma concentration (tmax) for each subject. Logarithmic transformation of the AUC and Cmax was used for the statistical analyses and to assess the bioavailability of the two formulations, using analyses of variance (ANOVA) and Satherwait t-tests for unequal variances. The ANOVA performed of tmax in Cmax, and in AUC provided the appropriate intra-subject variance estimates to evaluate the 90% confidence intervals for the differences between study variables after administration of the test and reference formulations. Statistical analyses were conducted on AUC 0-4 as the extrapolated part of the AUC, a truncated area approach was adapted. RESULTS: The mean pharmacokinetic parameters for both of the drugs under study were as follows: Cmax = 61.24 (+/- 12.96) ng/ml for the test formulation, and for the reference formulation Cmax = 61.39 (+/- 14.1) ng/ml, the effects were statistically equivalent. The tmax for the test formulation was 8.25 (+/- 1.7) and 7.33 (+/- 0.96) for the reference formulation. The area under the curve to infinity (AUC 0-infinity (ng, day/ml)) for the test formulation and for the reference formulation were 293.02 (+/- 52.69) and 296.15 (+/- 61.69), respectively. CONCLUSIONS: The two formulations had equivalent pharmacokinetic parameters, were well-tolerated, and their relative bioavailability was 98.94%.     

Bioequivalence of two oral ciprofloxacin tablets formulations

The relative bioavailability of a new 750 mg tablet formulation of ciprofloxacin (test formulation supplied by Dr. August Wolff GmbH and Co., Germany) was compared with that of Ciprobay tablets 750 mg (reference formulation from Bayer Vital GmbH and Co., Germany). Twenty-four healthy volunteers (12 male and 12 female) were included in this single-dose, 2-sequence, crossover randomized study. Blood samples were obtained prior to dosing and at 0.5, 0.75, 1, 1.5, 2, 3, 4, 6, 8, 10, 12, 18, 24 and 30 hours after drug administration. Plasma concentrations of ciprofloxacin were determined by HPLC. No differences were found when the in vitro dissolution profiles of both formulations were compared. The pharmacokinetic parameters AUC(0-t), AUC(0-infinity), Cmax and Cmax/AUC(0-infinity) were tested for bioequivalence after log-transformation of data, and ratios of tmax were evaluated nonparametrically. The parametric analysis revealed the following mean values for the test/reference ratios (90% standard confidence intervals in parenthesis (ln-transformed data): 1.01 (0.95-1.07) for AUC(0-t), 0.99 (0.93-1.05) for AUC(0-infinity), 1.05 (0.97-1.14) for Cmax and 1.06 (0.97-1.15) for Cmax/AUC(0-infinity). The nonparametric confidence interval for tmax was 0.77-1.15. All parameters showed bioequivalence between both formulations as their confidence intervals were within the bioequivalence acceptable range of 0.80-1.25 limits; the 90% confidence interval for tmax slightly exceeded limits of bioequivalence. We conclude that both formulations show bioequivalence for both the rate and the extent of absorption.     

盐酸二甲双胍片在中国健康人体的生物等效性

目的评价2种国产盐酸二甲双胍片(口服降糖药)在中国健康人体的生物等效性。方法 20名健康男性受试者随机交叉单剂量口服盐酸二甲双胍片试验药物和对照药物,各1.0 g。用高效液相色谱法测定血浆中盐酸二甲双胍的浓度,用DAS 2.0软件计算药代动力学参数,并对2种药物进行生物等效性评价。结果试验药物和对照药物的主要药代动力学参数如下:Cmax为(2.83±0.53),(2.57±0.57)mg.L-1;Tmax为(1.55±0.39),(1.63±0.36)h;t1/2为(3.70±1.76),(3.36±0.72)h;AUC0-24为(10.20±1.95),(9.71±2.56)mg.h.L-1。AUC0-24、AUC0-∞、Cmax的90%可信区间分别为99.1%～114.6%、99.1%～113.8%和100.6%～110.4%。试验药物相对于对照药物的生物利用度F为(108.3±20.5)%。结论试验药物和对照药物生物等效。     

Comparative bioavailability study of doxycycline hyclate (equivalent to 100 mg doxycycline) capsules (doxycin vs vibramycin) for bioequivalence evaluation in healthy adult volunteers

This investigation was carried out to evaluate the bioavailability of a new capsule formulation of doxycycline (100 mg), doxycin, relative to the reference product, vibramycin (100 mg) capsules. The bioavailability was carried out in 24 healthy male volunteers who received a single dose (100 mg) of the test (A) and the reference (B) products after an overnight fast of at least 10 hours on 2 treatment days. The treatment periods were separated by a 2-week washout period. A randomized, balanced 2-way cross-over design was used. After dosing, serial blood samples were collected for a period of 48 hours. Plasma concentrations of doxycycline were analyzed by a sensitive and validated high-performance liquid chromatography assay. The pharmacokinetic parameters for doxycycline were determined using standard noncompartmental methods. The parameters AUC(0-t), AUC(0-infinity), Cmax, K(el), t(1/2) and Cmax/AUC(0-infinity) were analyzed statistically using log-transformed data. The time to maximum concentration (tmax) was analyzed using raw data. The parametric 90% confidence intervals of the mean values of the pharmacokinetic parameters: AUC(0-t), AUC(0-infinity), Cmax and Cmax/AUC(0-infinity) were within the range 80-125% which is acceptable for bioequivalence (using log-transformed data). The calculated 90% confidence intervals based on the ANOVA analysis of the mean test/reference ratios of AUC(0-t), AUC(0-infinity), Cmax and Cmax/AUC(0-infinity) were 95.98-109.56%, 92.21 to 107.66%, 93.90-112.56%, and 96.0 to 106.91% respectively. The test formulation was found bioequivalent to the reference formulation with regard to AUC(0-t), AUC(0-infinity), Cmax and Cmax/AUC(0-infinity) by the Schuirmann's two 1-sided t-tests. Therefore, the 2 formulations were considered to be bioequivalent.     

Bioequivalence study of two limaprost alfadex 5 microg tablets in healthy subjects: moisture-resistant tablet (dextran formulation) versus standard tablet (lactose formulation)

OBJECTIVE: A study was conducted to assess the bioequivalence of two limaprost alfadex 5 microg tablets, a moisture-resistant tablet (dextran formulation) and a standard tablet (lactose formulation). MATERIALS AND METHODS: The clinical investigation was designed as a randomized, open-labeled, two-part, two-treatment, two-period crossover study, in 120 healthy male volunteers. One tablet of either formulation was administered with 200 ml of water after 10-hour overnight fast. After dosing, serial blood samples were collected for a period of 6 hours. Plasma harvested from blood was analyzed for limaprost by a validated LC/MS/MS method. The peak plasma concentration (Cmax) values and time associated with the maximal concentration (tmax) were obtained from the observed data. The elimination rate constant (lambda z) was obtained as the slope of the linear regression of the log-transformed concentration values vs. time data in the terminal phase, and the elimination half-life (t1/2) was calculated as 0.693/lambda z. The area under the curve to the last measurable point (AUC0-t) was estimated by the linear trapezoidal rule. The analysis of variance (ANOVA) was carried out using log-transformed AUC0-t, AUC0-A yen and Cmax and untransformed tmax, and 90% confidence intervals for AUC0-t and Cmax were calculated. If the 90% confidence intervals (CI) for both AUC0-t and Cmax fell fully within the interval 80 - 125%, the bioequivalence of the two formulations was established. RESULTS: The means of AUC0-t were 0.779 vs. 0.754 pg x h/ml (test vs. reference), and the means of the Cmax were 1.26 vs. 1.12 pg/ml (test vs. reference). The geometric mean ratios of the test formulation to reference formulation for AUC0-t and Cmax were 104.0 and 112.4%, respectively, and the 90% CI for AUC0-t and Cmax were 100.7 - 107.4% and 105.6 - 119.6%, respectively. Both 90% CI for AUC0-t and Cmax fell within the Ministry of Health, Labour and Welfare of Japan accepted bioequivalence range of 80 - 125%. CONCLUSIONS: Based on the results, the moisture-resistant tablet was determined to be bioequivalent to the standard tablet.     

The bioequivalence study of folifer-Z: a new formulation of sustained-release iron and zinc

The bioequivalence of Folifer-Z tablets, a new sustained-release iron and zinc formulation was evaluated and compared to that of Fefol-Z capsules in 30 healthy male subjects. Each subject received a single oral dose of either product according to a randomized two-way crossover design. A washout period of 1 week was allowed after each treatment. Blood samples were obtained over a 24-h period, and iron and zinc concentrations were measured. The pharmacokinetic parameters of Folifer-Z were Cmax (103 +/- 46.2 micrograms/dl), Tmax (5.93 +/- 2.94 h) and AUC0-24 h (1937 +/- 706 micrograms/dl per h), whereas the corresponding Fefol-Z values were Cmax (109 +/- 41.5 micrograms/dl), Tmax (6.64 +/- 2.54) and AUC0-24 h (1865 +/- 699 micrograms/h per dl). Analysis of variance on log-transformed data for Cmax and AUC0-24 h revealed lack of significant differences among the two formulations. The mean relative bioavailability of AUCtest/AUCreference was 1.07 (90% confidence interval range: 99-115%) and for Cmax test/Cmax reference was 0.96 (90% confidence interval range: 88-105%). Regarding the zinc results, the pharmacokinetic parameters of Folifer-Z values were Cmax (101 +/- 20.7 micrograms/dl), Tmax (4.86 +/- 1.53 h) and AUC0-24 h (1944 +/- 202 micrograms/h per dl), while the corresponding Fefol-Z values were Cmax (102 +/- 20.7), Tmax (4.93 +/- 1.51) and AUC0-24 h (1953 +/- 200). Analysis of variance on log-transformed zinc data for Cmax, Tmax and AUC0-24 h revealed lack of significant difference among the two formulations. The mean relative bioavailability of AUCtest/AUCreference was 0.98 (90% confidence interval range; 95-101%) and for Cmax test/Cmax reference was 0.92 (90% confidence interval range: 89-96%). The results also indicate a possible inhibition of zinc absorption by iron content of both formulations. It is concluded that Folifer-Z product is bioequivalent to Fefol-Z product.     

Comparative pharmacokinetic and relative bioavailability study of coated and uncoated azithromycin powder for suspension in healthy Bangladeshi male volunteers

Azithromycin (AZT; CAS 83905-01-5) is an efficient antibiotic and is widely prescribed in Bangladesh. The taste of uncoated AZT suspension is bitter. Although several taste masked oral suspensions of AZT are available in Bangladesh, information regarding the bioavailability of these formulations in Bangladeshi population is unavailable. The purpose of this study was to compare the relative bioavailability and other pharmacokinetic properties of two oral formulation of AZT (200 mg/5 ml) suspensions, the uncoated reference product and coated test product (Tridosil 200 mg/5 ml) and to evaluate whether these formulations meet the FDA criteria to assume bioequivalence in Bangladeshi male volunteers. A randomized, single-dose, two-way cross-over, open-label pharmacokinetic study was conducted in 24 healthy male volunteers after administration of a single dose of 500 mg AZT suspension under fasting condition following a washout period of three weeks. Blood samples were collected in different time intervals and analyzed for serum AZT concentration using a validated LC/MS/MS method. The pharmacokinetic parameters were determined by the non-compartmental method. From serum data, the obtained values for test and reference products were 383.21 +/- 11.59 and 432.28 +/- 7.22 ng/ ml for Cmax; 5677.47 +/- 1229.53 and 6144.56 +/- 1098.70 h x ng/ml for AUC(0-120); and 6085.29 +/- 1267.53 and 6694.15 +/- 1222.50 h x ng/ml for AUC(0-infinity), respectively. On analysis of variance, no period or sequence effects were observed for any pharmacokinetic property; however, a significant formulation effect was observed for Cmax and AUMC(0-infinity). The 90% confidence intervals of the test formulation/reference mean ratios of the Intransformed Cmax, AUC(0-120) and AUC(0-infinity) mean values were found to be 87.89% to 89.36%, 87.96% to 95.71% and 86.77% to 94.29% respectively. In this single-dose study of AZT, it was found that the test formulation met the regulatory criteria for bioequivalence to the reference suspension formulation.     

Bioavailability study of two different verapamil formulations.

Relative bioavailability and bioequivalence of two oral verapamil preparations were investigated (dosage 80 mg, film-coated tablets as reference, dragées as test formulation). The clinical study was performed in a 2-period-cross-over design with 16 male healthy volunteers (mean age 28.8 +/- 3 years). The active metabolite norverapamil was included in the investigation. To assess bioequivalence several pharmacokinetic characteristics (i.e. AUC(o-oo), Cmax, tmax) were taken into account. Shortest 90% confidence intervals were calculated based on parametric (ANOVA, ANOVAlog) and non-parametric (Wilcoxon, Mann-Whitney) statistical tests. A positive decision for bioequivalence was accepted if the confidence intervals did not exceed the limits of 80-120% for AUC and 70-130% for Cmax. A mean relative bioavailability of 127% for the test preparation was found. Thus, bioavailability of the dragées is marked higher than bioavailability of the film-coated tablets.     

Single-dose fasting bioequivalence assessment of erythromycin stearate tablets in man

The bioequivalence of film-coated erythromycin stearate tablets produced by five different manufacturers was evaluated in a balanced incomplete block design involving the five formulations given to 30 fasted subjects over a 3-week study period. Serum levels of erythromycin activity were determined microbiologically. Statistical analysis of variance was performed on the observed bioavailability parameters: maximum serum concentration (Cmax), time to maximum serum concentration (Tmax), and area under the serum concentration-time curve (AUC). There was no statistical difference between formulations for the Tmax parameter. Formulation differences were found, however, based on the analysis of variance of the Cmax and AUC parameters. Two products, although not significantly different from one another, showed significantly greater Cmax and AUC values than the other three products.     

Comparative bioequivalence study of leflunomide tablets in Indian healthy volunteers

The pharmacokinetics of teriflunomide [CAS No. 163451-81-8], the metabolite of leflunomide [CAS No. 75706-12-6] has been evaluated in adult human volunteers after oral administration of tablet formulation. However, no published data is available regarding the bioavailability of this in the Indian population. In light of the above, a study was designed to carry out a bioequivalence study of 2 preparations of leflunomide 20 mg in healthy Indian male volunteers.24 healthy male volunteers (age, 25±4.1 years; weight, 57.58±7.01 kg) were enrolled in this study. Each subject received a test and reference formulation in a single dose, fasting 2 period, 2 way crossover study with a wash out period of 4 weeks. Analysis of teriflunomide from plasma samples was done by a simple and sensitive HPLC method using UV detection developed in our laboratory. An analysis of variance was performed on the pharmacokinetic parameters Cmax, AUC0-t, AUC0-∞ using GLM procedures in which sources of variation were subject, formulation, and period.The results indicated that there are no statistically significant differences between the 2 products in either the mean concentration-time profiles or in the obtained pharmacokinetic parameters. 90% confidence limits for the log transformed data of Cmax, AUC0-t, AUC0-∞. were within the acceptable range of 0.80-1.25.The results indicate that the 2 products are bioequivalent in terms of rate and extent of drug absorption. Both the preparations were well tolerated with no adverse reactions throughout the study.     

Oxcarbazepine final market image tablet formulation bioequivalence study after single administration and at steady state in healthy subjects

A final market image (FMI) tablet formulation of oxcarbazepine was compared with the marketed formulation (current market formulation (CMF)) and with the clinical trial formulation (CTF) tablet used during clinical efficacy and safety studies. The goal of the study was to compare the bioavailability after single doses and at steady state of the FMI versus CMF and CTF as well. Additionally, the effect of food was evaluated on the final market formulation. The study was an open-label, single-center, 4-way crossover trial. Each treatment period consisted of a single dose of 600 mg OXC on Day 1. From Day 4 up to including Day 7, 600 mg b.i.d. were administered. A final dose of 600 mg was administered in the morning on Day 8. Blood samples were taken on Day 1 before and on Day 7 (predose) and on Day 8 (morning dose). Plasma concentrations of MHD (the main metabolite of OXC) were determined by using a validated HPLC assay. FMI as test formulation was compared with the CMF and CTF as reference formulations. FMI under fed conditions was also compared with FMI under fasting conditions. These comparisons were made using data following single-dose administration and steady state conditions. Plasma AUC for single dose or AUC(0-12h) for steady state, and plasma Cmax, log-transformed (natural base), were used for the assessment of bioequivalence. The 90% confidence interval (CI) approach was used for testing bioequivalence. Bioequivalence was accepted if the CI was contained within the region (0.8, 1.25). At steady state under fed conditions, tested formulation (FMI) was bioequivalent to CTF and with the reference marketed formulation (CMF) with regard to AUC and Cmax. After single dose under fed conditions, FMI and CTF were bioequivalent with regard to AUC and Cmax, and FMI and CMF were equivalent with regard to AUC but not Cmax. Food had no effect on the bioavailability of the FMI. These results clearly support the switch from the current market formulation (CMF) to the final market image tablet in the countries where Trileptal is or was already registered.     

Comparative bioavailability of two tablet formulations of fluphenazine dihydrochloride in drug-free psychiatric patients

The comparative bioavailability of a new tablet formulation of fluphenazine dihydrochloride (5 mg) and a reference product (fluphenazine dihydrochloride, Prolixin, 5 mg) was assessed in drug-free psychiatric patients. Twenty-six patients were initially entered in the study, of whom 22 completed the protocol. Each patient received the test (T) and the reference formulation (R) in a balanced two-way crossover design. Plasma concentrations of fluphenazine were monitored over a period of 48 h after drug administration using a sensitive HPLC method. One patient did not show any measurable plasma concentration for one formulation at any sampling time and, therefore, bioavailability was assessed in the remaining 21 patients. All pharmacokinetic parameters showed wide intersubject variation. The maximum plasma concentration (Cmax), time to Cmax, and area under the curve up to the last measurable concentration (AUClast0), infinity (AUCinfinity0), or truncated areas (such as AUC16(0), AUC24(0) were compared by analyses of variance and found not to be significantly different in each case across the formulations. Except for AUC24(0), AUC32(0), and AUC48(0), ANOVA of all other parameters showed a high power (greater than 80%) to detect a 20% difference in the mean value of each bioequivalence parameter between T and R. The two formulations were found to be bioequivalent in that confidence intervals of the mean values of AUCinfinity0, AUClast0, truncated AUCs, or Cmax for T:R ratios were, in each case, well within the acceptable range of 100 +/- 20%.     

阿德福韦酯胶囊人体生物等效性研究

目的：评价国产阿德福韦酯胶囊与进口阿德福韦酯片（贺维力）的生物等效性。方法：20位健康男性志愿者随机交叉口服单剂量受试制剂（阿德福韦酯胶囊）和参比制剂（贺维力）;用LC-MS/MS法,分别测定药物血浆浓度,DAS2.0计算药代动力学参数,评价生物等效性。结果：受试制剂和参比制剂的主要药代动力学参数,AUC0-t分别为（207.92±45.80）ng.h-1.mL-1和（221.25±54.18）ng.h-1.mL-1,AUC0-∞分别为（217.16±45.93）ng.h-1.mL-1和（230.63±53.80）ng.h-1.mL-1,Cmax分别为（17.61±3.21）ng.mL-1和（19.76±4.64）ng.mL-1,Tmax分别为（1.70±0.64）h和（1.33±0.61）h,t1/2分别为（8.10±1.12）h和（8.11±1.34）h。AUC0-t、AUC0-∞和Cmax90%可信区间分别为89.8%～99.2%、90.2%～98.9%和82.4%～98.0%;相对生物利用度为（95.1±11.9）%（以AUC0-t计）、（95.1±11.1）%（以AUC0-∞计）。结论：2种制剂具有生物等效性。     

盐酸特比萘芬片在健康人体中的相对生物利用度及生物等效性试验

目的:评价盐酸特比萘芬片在健康人体的相对生物利用度和生物等效性。方法:20名健康受试者随机交叉单剂量口服盐酸特比萘芬片受试制剂(T)和参比制剂(R),采用液质联用分析方法(LC-MS/MS)测定血浆中特比萘芬浓度。结果:20名健康受试者口服受试制剂和参比制剂后的主要药代动力学参数为:Tmax分别为(1.7±0.6)和(2.2±0.7)h;Cmax分别为(1 590±489)和(1 266.6±432.8)ng·mL-1;t1/2分别为:(21.6±3.6)和(21.0±10.1)h;AUC0～t分别为(8 272.2±2 280.6)和(8 138.9±2 424.0)ng·h·mL-1。受试制剂的AUC0～t或Cmax的90%置信区间对应于参比制剂相应参数的93.44%～111.87%或112.83%～141.91%范围内;受试制剂相对于参比制剂的相对生物利用度为(105.5±26.3)%。结论:受试制剂与参比制剂的生物利用度相当,但受试制剂峰浓度增加,达峰时间提前,没有增加不良反应,疗效也未见降低。     

Comparative bioavailability study of cefixime (equivalent to 100 mg/5 ml) suspension (Winex vs Suprax) in healthy male volunteers

This investigation was carried out to evaluate the bioavailability of a new suspension formulation of cefixime (100 mg/5 ml), Winex, relative to the reference product, Suprax (100 mg/5 ml) suspension. The bio-availability study was carried out in 24 healthy male volunteers who received a single oral dose (200 mg) of the test (A) and the reference (B) products on 2 treatment days after an overnight fast of at least 10 hours. The treatment periods were separated by a one-week washout period. A randomized, balanced two-way crossover design was used. After dosing, serial blood samples were collected over a period of 16 hours. Plasma concentrations of cefixime were analyzed using a sensitive high-performance liquid chromatographic assay. The pharmacokinetic parameters for cefixime were determined using standard non-compartmental method. The parameters AUC(0-t), AUC(0-infinity), Cmax, Kel, t1/2 and Cmax/AUC(0-infinity) were analyzed statistically using raw and log-transformed data. The time to maximum concentration (tmax) was analyzed using raw data. The parametric 90% confidence intervals of the mean values of the pnfinity harmacokinetic parameters: AUC(0-t), AUC(0-infinity) Cmax, and Cmax/AUC(0-infinity) were within the range 80 - 125% which is acceptable for bioequivalence (using log-transformed data). The calculated 90% confidence intervals based on the ANOVA analysis for the mean test/reference ratios of AUC(0-t), AUC(0-infinity), Cmax, and Cmax/AUC(0-infinity) were 88.93 - 107.10%, 89.09 - 107.11%, 89.63 - 108.58% and 96.85 - 105.29%, respectively. The test formulation was found bioequivalent to the reference formulation with regard to AUC(0-t), AUC(0-infinity), and Cmax using the Schuirmann's two one-sided t-tests. Therefore, the two formulations were considered to be bioequivalent.     

盐酸左氧氟沙星片的人体生物等效性研究

目的研究盐酸左氧氟沙星片的人体相对生物利用度和生物等效性。方法健康志愿者20名,随机双交叉单剂量口服盐酸左氧氟沙星片试验和参比制剂,剂量分别为200mg,剂间间隔为1周。分别于服药后24h内多点抽取静脉血;用高效液相色谱（HPLC）法测定血浆中左氧氟沙星的浓度。用DAS药代动力学程序计算相对生物利用度并评价两种制剂生物等效性。AUC（0-24）,AUC（0-inf）和Cmax经方差分析和双单侧t检验,Tmax进行秩和检验。结果单剂量口服试验制剂和参比制剂后血浆中的左氧氟沙星的Cmax分别为（2.88±0.61）mg·L^-1和（2.90±0.58）mg·L^-1;Tmax分别为（1.17±0.62）h和（1.09±0.79）h;AUC（0-24）分别为（20.23±3.41）mg/（h·L）和（20.11±3.61）mg/（h·L）;AUC（0-inf）分别为（21.97±3.84）mg/（h·L）和（21.72±4.22）mg/（h·L）。AUC（0-24）、AUC（0-inf）和Cmax的90%可信区间分别为97.5%～104.2%、98.2%～104.9%和92.5%～106.5%。结论试验制剂与参比制剂的人体相对生物利用度为（97．53±18．49）％,2制剂具有生物学等效性。     

泛昔洛韦片的人体生物等效性研究

目的研究泛昔洛韦片的人体相对生物利用度和生物等效性。方法健康志愿者20名,随机双交叉单剂量口服泛昔洛韦片（试验和参比制剂）。剂量分别为0．5g,剂间间隔为1周。分别于服药后12h内多点抽取静脉血;用高效液相色谱（HPLC）法测定血浆中喷昔洛韦的浓度。用DAS药代动力学程序计算相对生物利用度并评价两种制剂生物等效性。AUC（0-12）．AUC（0-∞）和Cmax经方差分析和双单侧t检验,Tmax进行秩和检验。结果单剂量口服泛昔洛韦试验和参比制剂后,血浆喷昔洛韦的Cmax分别为（2．92±0．76）mg·L^-1和（2．98±1．00）mg·L^-1;Tmax分别为（1．04±0．46）h和（1．17±0．61）h;AUC（0-12）分别为（8．51±2．46）mg·h·L^-1和（8．73±2．86）mg·h·L^-1;AUC（0-∞）分别为（8．87±2．57）mg·h·L^-1和（9．10±2．99）mg·h·L^-1。AUC（0-12）、AUC（0-∞）和Cmax的90％可信区间分别为83．9％～99．6％、83．5％～99．2％和92．4％～108．1％。结论试验制剂的相对生物利用度为（97．53±18．49）％;两制剂具有生物学等效性。     

Pharmacokinetics and bioequivalence study of two digoxin formulations after single-dose administration in healthy Chinese male volunteers

The pharmacokinetics and relative bioavailability/bioequivalence of two formulations of digoxin (CAS 20830-75-5) were assessed in this paper. The study was conducted in 20 healthy Chinese male volunteers according to an open, randomized, single-blind, 2-way crossover study design with a wash-out phase of 14 days. Blood samples for pharmacokinetic profiling were taken up to 72 h post-dose and digoxin plasma concentrations were determined by a validated liquid chromatography-tandem mass spectrometry (LCMS/MS) method. Based on the plasma concentration-time data of each individual during two periods, pharmacokinetic parameters, Cmax, AUC0-tau, AUC0-infinity and t1/2, were calculated by applying noncompartmental analysis. Pharmacokinetic data for test and reference formulations were analyzed statistically to evaluate bioequivalence of the two formulations. After oral administration, the values of Cmax Tmax, t1/2, AUC0-tau, AUC0-infinity for test and reference formulations were 2.61 +/- 0.98 and 2.68 +/- 1.09 ng/ mL, 1.0 +/- 0.4 and 1.0 +/- 0.4 h, 27.94 +/- 3.14 and 27.56 +/- 3.86 h, 28.57 +/- 4.99 and 28.77 +/- 6.53 ng x h/mL, 33.44 +/- 4.85 and 33.63 +/- 7.57 ng x h/mL, respectively. Both primary target parameters, AUC0-infinity and AUC0-tau, were tested parametrically by analysis of variance (ANOVA). Relative bioavailabilities were 102.5 +/- 19.2% for AUC0-infinity, 102.0 +/- 19.3% for AUC0-tau. Bioequivalence between test and reference formulations was demonstrated for both parameters, AUC0-infinity and AUC0-tau. The 90% confidence intervals of the T/R-ratios of logarithmically transformed data were in the generally accepted range of 80%-125%, which means that the test formulation is bioequivalent to the reference formulation of digoxin.     

Assessment of the bioequivalence of two oxcarbazepine oral suspensions versus a film-coated tablet in healthy subjects

Oxcarbazepine (trileptal) oral suspension has been reformulated and a study was performed to compare the bioavailability after single doses and at steady state of the current and former oral suspension versus the marketed film-coated tablets and to compare the bioavailability of the current and former oral suspension. The results support the switch from the former oral suspension to the current oral suspension and also from both oral suspensions to the film-coated tablet and vice versa. The study was an open-label, single-center, 3-way crossover trial. Each treatment period consisted of a single dose of 600 mg oxcarbazepine on Day 1, 600 mg oxcarbazepine b.i.d. repeated administration from Day 4 up to including Day 7, and a final dose of 600 mg oxcarbazepine administered on the morning of Day 8. Blood samples were taken on Day 1, Day 7 and Day 8 (pre-dose). Plasma concentrations of the main metabolite of oxcarbazepine (MHD) were determined using a validated HPLC assay. The 2 oral suspensions were compared with the film-coated tablet as reference formulation under fasted conditions. Also the current oral suspension was compared with the former oral suspension. These comparisons were made using data following single dose administration and under steady state conditions. Plasma AUC for single dose and AUC(0-12h) at steady state and plasma Cmax, log-transformed (natural base) were used for the assessment of bioequivalence. The 90% confidence interval (CI) approach was used for testing bioequivalence. Bioequivalence was accepted if CI was contained within the region (0.8, 1.25). At steady state, both the former and the current oral suspensions showed bioequivalence with the film-coated tablet with respect to AUC and Cmax. The current oral suspension was also bioequivalent when compared to the former oral suspension with respect to AUC and Cmax. After single dose, the former oral suspension was bioequivalent when compared to the film-coated tablet with respect to both AUC and Cmax. However, the current oral suspension was bioequivalent to both the film-coated tablet and the former oral suspension with respect to AUC but not to Cmax.