Bioequivalence Evaluation Research Articles

Using DTA and DTAARRAY variables and programming in WinNonlin ASCII models to streamline user-defined calculation and data analysis.

In pharmacokinetic (PK) analysis, there are many occasions where user-defined calculations need to be performed before or after the primary PK modeling/analysis. Conventionally, these calculations are often executed outside of the primary PK analysis by pre- or post-processing data from multiple sources, manually entering formulas and multiple additional set-ups. Such analysis approaches increase the risk of generating data defects and can employ software that is not fully compliant. We propose a method of leveraging DTA and DTAARRAY variables plus simple programming techniques in an ASCII model to automate these user-defined calculations in WinNonlin and eliminate the need for manual handling of data outside of the primary analysis. We demonstrated the application of this strategy through three case study examples. In case 1 (post-processing data), DTA variables were used to calculate three user-defined parameters in the primary PK model. In case 2 (pre-processing data), a baseline correction decision tree was programmed into the PK model to account for both the endogenous baseline level as well as the presence of residual drug. In case 3, DTAARRAY variables were used to perform a looping operation to calculate the difference factor (F1) and the similarity factor (F2) in support of in vitro bioequivalence evaluations.

Bioequivalence of topical corticosteroids: Design and data analysis challenges with the vasoconstrictor assay

T vasoconstrictor assay (VCA) method published in FDA’s 1995 Guidance on bioequivalence of topical dermatologic corticosteroids is currently the only pharmacodynamic method approved by FDA for demonstrating bioequivalence of topical corticosteroid products (gels, creams, lotions, ointments, foams, tapes and sprays). The Guidance recommends a pilot dose durationresponse study to determine the appropriate dose duration for use in the pivotal study. In general, evaluation of bioequivalence by the VCA method has worked well over the last 20 years, but there remain several challenges in design and data analysis. For example, for the dose-response study the fit of the simple Emax model is not always optimal with low potency products, with products that show delayed vasoconstrictor (skin blanching) response, or with subjects that have low skin blanching (low Emax); for the pivotal study a too short or very long ED50 duration products can pose operational challenges. Furthermore, the sample size recommendation in the Guidance of 40-60 qualifiers for pivotal studies may be too low for those products that show high intra-subject variability in vasoconstrictor response. Successful bioequivalence studies depend on the clinic’s ability to recruit a fair-skinned population of subjects that show high and consistent skin blanching to even low potency topical steroids so that within-subject variability in vasoconstrictor response is minimized. This presentation will discuss approaches for minimizing operational issues, estimating sample size, and evaluating reliability of blanching profiles for pivotal studies and will provide examples of design and data analysis challenges for dose-response and pivotal studies.

Evaluation of bioequivalence of five 0.1 mg dutasteride capsules compared to one 0.5 mg dutasteride capsule: a randomized study in healthy male volunteers

Objective:To evaluate the bioequivalence of five 0.1 mg dutasteride capsules to one 0.5 mg dutasteride capsule in healthy adult male subjects under fasting conditions.Methods:This was a single-center, open-label, randomized, single dose, two-way cross-over study (ClinicalTrials.gov identifier NCT01929330). Thirty-six healthy male subjects aged 18–65 years received 5 × 0.1 mg dutasteride softgel capsules and 1 × 0.5 mg dutasteride softgel capsule in a randomized order, with a minimum washout of 28 days between each drug administration. Serial blood samples were collected for the measurement of serum dutasteride concentrations by a validated HPLC-MS/MS method. Dutasteride pharmacokinetic parameters were calculated using non-compartmental analysis. Maximum concentration (Cmax) and area under the concentration-time curve to the last quantifiable concentration (AUC[0–t]) were compared between treatments. Safety and tolerability were monitored throughout the study.Results:Five 0.1 mg dutasteride capsules were demonstrated to be bioequivalent to 1 × 0.5 mg dutasteride capsule, as the 90% confidence intervals for Cmax and AUC were within the accepted bioequivalence range of 0.80–1.25. The geometric least squares means ratios and associated 90% confidence intervals for 5 × 0.1 mg capsules vs 1 × 0.5 mg capsule were 1.01 (0.97–1.05) for Cmax and 0.91 (0.84–1.00) for AUC(0–t). Adverse events (AEs) were reported for 42% (15/36) and 36% (12/33) of subjects in the 5 × 0.1 mg and 1 × 0.5 mg dosing sessions, respectively. The most frequent AE for both treatments was headache. No subject had a serious AE.Conclusions:Five 0.1 mg dutasteride capsules were shown to be bioequivalent to one 0.5 mg dutasteride capsule in healthy adult male subjects under fasted conditions, suggesting that the two dose strengths can be interchanged. Both treatments were generally well tolerated in healthy male subjects.

Human bioequivalence evaluation of two losartan potassium tablets under fasting conditions.

The bioequivalence of two different tablet formulations containing losartan potassium 100 mg was determined in healthy volunteers after a single oral dose in a randomized crossover study. Test and reference products were administered to 60 volunteers with 240 ml water after overnight fasting. Plasma concentrations of losartan and its active carboxylic acid metabolite were monitored over a period of 36 h after drug administration by validated LC/MS/MS analytical method. The pharmacokinetic parameters Cmax, AUC0-t, AUC0-∞, AUC0-t/AUC0-∞, tmax, Kel and t½ were determined from plasma concentration time profile of both formulations for losartan and its active metabolite losartan carboxylic acid and were found to be in good agreement. The carboxylic acid metabolite was considered for profiling purpose only. The analysis of variance did not show any significant difference between the two formulations and 90% confidence intervals for the ratio of Cmax (84.89-104.09%), AUC0-t (95.84-102.84%) and AUC0-∞ (96.43-103.25%) values for losartan between the test and reference products were within the 80-125% interval, satisfying the bioequivalence criteria of the US FDA guidelines. These results indicate that the test and the reference products of losartan potassium are bioequivalent and, thus, may be prescribed interchangeably.

Pharmacokinetic interactions between primaquine and pyronaridine-artesunate in healthy adult Thai subjects.

Pyronaridine-artesunate is a newly introduced artemisinin-based combination treatment which may be deployed together with primaquine. A single-dose, randomized, three-sequence crossover study was conducted in healthy Thai volunteers to characterize potential pharmacokinetic interactions between these drugs. Seventeen healthy adults received a single oral dose of primaquine alone (30 mg base) and were then randomized to receive pyronaridine-artesunate alone (540−180 mg) or pyronaridine-artesunate plus primaquine in combination, with intervening washout periods between all treatments. The pharmacokinetic properties of primaquine, its metabolite carboxyprimaquine, artesunate, its metabolite dihydroartemisinin, and pyronaridine were assessed in 15 subjects using a noncompartmental approach followed by a bioequivalence evaluation. All drugs were well tolerated. The single oral dose of primaquine did not result in any clinically relevant pharmacokinetic alterations to pyronaridine, artesunate, or dihydroartemisinin exposures. There were significantly higher primaquine maximum plasma drug concentrations (geometric mean ratio, 30%; 90% confidence interval [CI], 17% to 46%) and total exposures (15%; 6.4% to 24%) during coadministration with pyronaridine-artesunate than when primaquine was given alone. Pyronaridine, like chloroquine and piperaquine, increases plasma primaquine concentrations. (This study has been registered at ClinicalTrials.gov under registration no. NCT01552330.)

Scientific Factors and Current Issues in Biosimilar Studies

Biological drugs are much more complicated than chemically synthesized, small-molecule drugs; for instance, their size is much larger, their structure is more complicated, they can be sensitive to environmental conditions such as temperature or pressure, and they may expose patients to immunogen reactions. Consequently, the assessment of biosimilarity calls for greater circumspection than the evaluation of bioequivalence. The present communication discusses scientific factors and some current issues related to biosimilarity and the interchangeability of drug products. The scientific factors include questions involving endpoint selection, the one-size-fits-all criterion, and the need for a more flexible approach, e.g., evaluation of the degree of similarity (i.e., responding to the question of “how similar is similar?”; a review of study designs that are useful for the assessment of biosimilarity and drug interchangeability; and tests for the comparability of critical quality attributes at various stages of the manufacturing process). Current issues include the choice of reference standards and the relevant study designs; criteria for biosimilarity, as well as for interchangeability and for comparability; the determination of the noninferiority margin; and the concepts of the stepwise approach to biosimilarity studies and of their assessment by the totality of the evidence. The calculation of sample sizes is discussed for crossover (including some higher-order schemes) and parallel designs.

Sample size determination for individual bioequivalence inference.

Statistical criterion for evaluation of individual bioequivalence (IBE) between generic and innovative products often involves a function of the second moments of normal distributions. Under replicated crossover designs, the aggregate criterion for IBE proposed by the guidance of the U.S. Food and Drug Administration (FDA) contains the squared mean difference, variance of subject-by-formulation interaction, and the difference in within-subject variances between the generic and innovative products. The upper confidence bound for the linearized form of the criterion derived by the modified large sample (MLS) method is proposed in the 2001 U.S. FDA guidance as a testing procedure for evaluation of IBE. Due to the complexity of the power function for the criterion based on the second moments, literature on sample size determination for the inference of IBE is scarce. Under the two-sequence and four-period crossover design, we derive the asymptotic distribution of the upper confidence bound of the linearized criterion. Hence the asymptotic power can be derived for sample size determination for evaluation of IBE. Results of numerical studies are reported. Discussion of sample size determination for evaluation of IBE based on the aggregate criterion of the second moments in practical applications is provided.

Determination of ambroxol hydrochloride in human plasma by ultra high performance liquid chromatography-tandem mass spectrometry and bioequivalence evaluation of its preparation

A rapid, simple and sensitive ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed for the determination of ambroxol hydrochloride in human plasma, and bioequivalence of its preparation was evaluated. The 50 μL-plasma sample was treated with methanol for protein precipitation, while ambroxol-d5 was used as an internal standard (IS). The separation was carried out on a Waters XBridge BEH C18 column (50 mm×2.1 mm, 2.5 μm) by gradient elution at a flow rate of 0.4 mL/min, with 0.1% (v/v) formic acid aqueous solution and methanol containing 0.1% (v/v) formic acid as the mobile phases. The analyte was detected using an electrospray ionization source in positive ion multiple reaction monitoring (MRM) mode. The calibration curves were linear in the range of 2-400 ng/mL (r=0.998). The intra- and inter-run accuracies were 97.1%-108.7%, the intra- and inter-run precisions were 1.0%-5.6%. The method was applied to the determination of the plasma concentration of the six healthy subjects after the oral administration of 30 mg of test and reference preparations. The bioavailability was (102.3±14.8)%. The 90% confidence intervals of the test preparation's pharmacokinetic parameters were 80.0%-125.0% of the reference preparation's corresponding parameters. Thus, it is proved that the test preparation and reference preparation are bioequivalent.

Inflation of the type I error: investigations on regulatory recommendations for bioequivalence of highly variable drugs.

We investigated different evaluation strategies for bioequivalence trials with highly variable drugs on their resulting empirical type I error and empirical power. The classical 'unscaled' crossover design with average bioequivalence evaluation, the Add-on concept of the Japanese guideline, and the current 'scaling' approach of EMA were compared. Simulation studies were performed based on the assumption of a single dose drug administration while changing the underlying intra-individual variability. Inclusion of Add-on subjects following the Japanese concept led to slight increases of the empirical α-error (≈7.5%). For the approach of EMA we noted an unexpected tremendous increase of the rejection rate at a geometric mean ratio of 1.25. Moreover, we detected error rates slightly above the pre-set limit of 5% even at the proposed 'scaled' bioequivalence limits. With the classical 'unscaled' approach and the Japanese guideline concept the goal of reduced subject numbers in bioequivalence trials of HVDs cannot be achieved. On the other hand, widening the acceptance range comes at the price that quite a number of products will be accepted bioequivalent that had not been accepted in the past. A two-stage design with control of the global α therefore seems the better alternative.

Современные критерии исследований биоэквивалентности лекарственных средств: гармонизация национальных стандартов

В настоящее время гармонизация национальных стандартов в сфере обращения лекарственных средств является одной из актуальнейших задач, стоящих перед государством, важность которой повысилась после вступления России во Всемирную торговую организацию (ВТО). Кроме законов, регулирующих лекарственное обращение, пересмотра и обновлений также требуют многочисленные подзаконные акты. Руководство по исследованию биоэквивалентности лекарственных средств является одним из определяющих нормативных документов при рассмотрении вопроса регистрации и контроля качества лекарственных препаратов. По мнению экспертного и врачебного сообществ, действующее в России руководство не соответствует международным требованиям и требует доработки. Приведен ряд международных критериев, использующихся при исследовании биоэквивалентности лекарственных препаратов. В целях повышения уровня качества лекарственных средств на российском фармацевтическом рынке нами указаны существующие и предложены дополнительные характеристики по исследованию биоэквивалентности, требующие изменения и дополнения для соответствия документа международным стандартам.

A sequential bioequivalence design with a potential ethical advantage.

This paper introduces a two-stage approach for evaluation of bioequivalence, where, in contrast to the designs of Diane Potvin and co-workers, two stages are mandatory regardless of the data obtained at stage 1. The approach is derived from Potvin's method C. It is shown that under circumstances with relatively high variability and relatively low initial sample size, this method has an advantage over Potvin's approaches in terms of sample sizes while controlling type I error rates at or below 5% with a minute occasional trade-off in power. Ethically and economically, the method may thus be an attractive alternative to the Potvin designs. It is also shown that when using the method introduced here, average total sample sizes are rather independent of initial sample size. Finally, it is shown that when a futility rule in terms of sample size for stage 2 is incorporated into this method, i.e., when a second stage can be abolished due to sample size considerations, there is often an advantage in terms of power or sample size as compared to the previously published methods.

Modeling and simulation of biopharmaceutical performance.

Biopharmaceutical performance refers to the influence of pharmaceutical formulation variables on in vivo performance. New drug product success depends on formulation design for sufficient bioavailability for clinically desired dosing. Regulatory interest in biopharmaceutical performance includes batch-to-batch consistency, acceptability of postapproval changes, and evaluation of bioequivalence (BE) for generic drug products. This Commentary summarizes biopharmaceutical modeling and simulation in the US Food and Drug Administration (FDA) Office of Generic Drugs (OGD) for orally administered generic drugs.

Sequential Bioequivalence Approaches for Parallel Designs

Regulators in EU, USA and Canada allow the use of two-stage approaches for evaluation of bioequivalence. The purpose of this paper is to evaluate such designs for parallel groups using trial simulations. The methods developed by Diane Potvin and co-workers were adapted to parallel designs. Trials were simulated and evaluated on basis of either equal or unequal variances between treatment groups. Methods B and C of Potvin et al., when adapted for parallel designs, protected well against type I error rate inflation under all of the simulated scenarios. Performance characteristics of the new parallel design methods showed little dependence on the assumption of equality of the test and reference variances. This is the first paper to describe the performance of two-stage approaches for parallel designs used to evaluate bioequivalence. The results may prove useful to sponsors developing formulations where crossover designs for bioequivalence evaluation are undesirable.

Physicochemical and Bioequivalence Studies on Some Brands of Levofloxacin Tablets Registered in Nigeria

Aims: This study was aimed at comparing the physicochemical and bioavailability profiles of some brands of Levofloxacin 500mg tablets that are registered in Nigeria by her regulatory authority and to examine the feasibility of interchangeability of the brands. Methodology: The physicochemical equivalence of ten brands of Levofloxacin 500 mg tablets (LEV-1 to LEV-10) were evaluated using both official and unofficial standards including weight variation, hardness, friability test, chemical assay, disintegration, dissolution rate and drug content. Five of the brands were also evaluated for bioavailability profiles using a single dose randomized two period cross–over designs measuring the concentration of drugs in the urine. Urinary samples before dosing and at various appropriate time intervals up to 12 hours were analyzed by validated Double Beam U. V. Spectrophotometer method with 99.8% extraction recovery. Pharmacokinetic parameters for bioequivalence evaluation Cmax, Tmax and AUC were determined. Results: The resultsshowed that 60% of the levofloxacin brands (LEV-2, LEV-4, LEV-5, LEV-7, LEV-8 and LEV-9) failed in at least one of the tested physicochemical parameters. The statistical comparison of the physicochemical parameters showed no difference between the innovator brand (LEV-1) and three of the tested generic brands (LEV-3, LEV-6 and LEV-10). Unlike LEV-5, the results obtained from the reference ratios of the parameters from bioavailability studies for the physicochemical equivalent brands were found to be within bioequivalence acceptable range with the reference brand indicating that they are bioequivalent in terms of Cmax and AUC to the innovator brand. Conclusion: The study indicates that 60% of the brands may not be used interchangeably with the innovator brand; consequently, the therapeutic substitution of these brands is not advisable. The formulation and/or the manufacturing process affect the weight uniformity, content uniformity, dissolution and thus the bioavailability of the drug products.

Pharmacokinetic comparison and bioequivalence evaluation of losartan/ hydrochlorothiazide tablet between Asian Indian and Japanese volunteers

To demonstrate the bioequivalence between the test and reference formulations of losartan/hydrochlorothiazide 50 + 12.5 mg tablet and evaluate the effect of ethnicity on pharmacokinetics properties of losartan, losartan carboxylic acid and hydrochlorothiazide on healthy Asian Indian and Japanese volunteers. Randomized, open-label, crossover, bioavailability studies were conducted separately in healthy Asian Indian and Japanese volunteers. One tablet either of test or of reference product was administered after 10 hours of overnight fasting. After dosing, serial blood samples were collected for a period of 48 hours for both the studies. Plasma samples were analyzed for losartan, losartan carboxylic acid and hydrochlorothiazide by a validated liquid chromatographic and mass spectrometric method (LC-MS/MS). The pharmacokinetic parameters AUC0-t, AUC0-∞, Cmax, tmax, and other pharmacokinetics parameters were determined from plasma concentration-time profiles for both test and reference formulations of losartan/hydrochlorothiazide 50 + 12.5 mg tablets. Statistical evaluations were done to evaluate bioequivalence between generic test formulation (EPR0001) and Japanese reference product (Preminent®). Losartan, losartan carboxylic acid and hydrochlorothiazide were well tolerated by subjects in all periods of each study under fasted conditions. No serious adverse events were observed. The ratios of least square means for AUC0-t and Cmax and the affiliated 90% confidence intervals were within acceptance range recommended by PMDA. Marginal differences were observed in pharmacokinetic values of Asian Indian and Japanese volunteers. The results of these bioavailability studies indicate that the test formulation of losartan/hydrochlorothiazide 50 + 12.5 mg (EPR0001) tablets is bioequivalent to marketed Preminent® reference formulation in Asian Indian and Japanese volunteers, when administered under fasting conditions. Both test and reference formulations were well tolerated as a single oral dose when administered to healthy adult subjects under fasted conditions. Although Asian Indian and Japanese volunteers are ethnically different, results of these studies indicate that pharmacokinetic parameters of Asian Indian and Japanese volunteers are comparable to each other in terms of bioavailability of losartan, losartan carboxylic acid and hydrochlorothiazide. Similar least square means ratios were obtained in Asian Indian and Japanese volunteers demonstrating that a bioequivalence study conducted on Japanese volunteers seems to be substituted by Asian Indian volunteers' studies.

In Vitro and In Vivo Equivalence Testing of Nanoparticulate Intravenous Formulations

The topic of bioequivalence evaluation of nanoparticulate intravenous formulations is one that has been intensely debated in recent times since the release of the specific recommendations by many regulatory authorities worldwide. Product specific bioequivalence guidelines for many of the nanoparticulate systems where therapeutic molecules are directly coupled (human albumin bound paclitaxel nanosuspension), functionalized (iron- carbohydrate preparations) or entrapped/coated to a carrier (doxorubicin liposomal formulations), have been approved by the drug regulatory agencies. These current regulatory procedures include complete characterization of the generic formulation in terms of its physicochemical characteristics, pharmacokinetics disposition and/or non clinical testing with respect to the reference formulation. The concept of in vitro equivalency is emerging as a valuable tool in these guidances as generic product differing in in vitro parameters can result in a different biopharmaceutical profile with respect to pharmacokinetics and biodistribution. Furthermore, in case of systems with entrapped drug, classical pharmacokinetic parameters alone may only ensure the equivalent clearance of test and reference product from systemic circulation but may fail to detect the extent to which the nanoparticles are taken up by different target organs and, consequently, the safety and efficacy effects. Hence, additional tissue distribution study in preclinical study models has reflected in recent guidances. Understanding and interpretation of these regulatory requirements thus presents most critical component of a generic product development cycle. This article reviews these current regulatory procedures with special emphasis on in vitro population bioequivalence (POP BE) and preclinical testing of generic formulations.

In vitro dissolution and in vivo bioequivalence evaluation of two brands of trimetazidine tablets.

Trimetazidine is an effective anti-anginal agent and anti-ischaemic effect. The objective of this study was to assess the in vitro dissolution and to evaluate the bioavailability of two brands of trimetazidine dihydrochloride tablets. Prior to the in vivo PKs study, an in vitro comparative dissolution test was performed for 2 oral brands of trimetazidine dihydrochloride tablets (20 mg). In vivo PKs study was evaluated in 24 healthy male volunteers after a single dose oral administration in an open, randomized, two-way crossover study with a washout period of 1 week. After an overnight fast, human volunteers were randomly allocated to receive a single dose of either test or reference product. Blood samples were collected over a 24-hour period following drug administration and plasma was analyzed for trimetazidine concentrations using a validated high-performance liquid chromatography assay method. The PK parameters Cmax , AUC0-t , AUC0-∞ , tmax , and t1/2 were determined from plasma concentration-time profiles. The 90% confidence intervals for the ratio of log transformed values of Cmax , AUC0-t , and AUCt-∞ of the test product over those of reference were within the acceptable range (0.8-1.25) for bioequivalence. As a result, the 2 trimetazidine formulations are considered bioequivalent and thus could be prescribed interchangeably in the medical practice based on its PK effect and biopharmaceutical performance.

Bioavailability, bioequivalence, and in vitro-in vivo correlation of oxybutynin transdermal patch in rabbits.

The first objective of the proposed research work includes comparative bioavailability and bioequivalence evaluation of oxybutynin transdermal patch with respect to different permeation enhancers. The second objective was to evaluate different in vitro methods along with synthetic membranes toward development of an in vitro-in vivo correlation. Oleic acid (fatty acid), Soluphor P (2-pyrrolidone, cosolvent), menthol (volatile oil), and dipropylene glycol (plasticizer) were selected as representatives from different classes of permeation enhancers. A random, crossover, single-dose pharmacokinetic study was carried out on male New Zealand white rabbits to determine bioavailability and bioequivalence. The obtained pharmacokinetic data were correlated with in vitro drug release using convolution-deconvolution approach. All developed formulations were found to be bioequivalent with respect to the marketed patch (Oxytrol®) on the basis of level of C max, AUC0-96, and AUCtotal (0.8-1.25). A biphasic linear correlation was obtained pertaining to differential diffusion behavior of the drug in vivo during the experimental timeframe. Because of close resemblance to skin, Cuprophan® membrane was found to be more suitable for developing an IVIVC than Millipore® membrane.

Pharmacokinetics and Bioequivalence Evaluation of Leflunomide Tablets in Korean Healthy Volunteers

Leflunomide is a disease-modifying antirheumatic drug. The purpose of this study was to evaluate the bioequivalence of a test drug (CJ leflunomide) and a commercially available reference drug (Arava®) at 2 doses (10 and 20 mg) in healthy Korean volunteers. This was a single-dose (28 individuals enrolled at each dose group), randomized, open-label, 2-way crossover study. The 2 treatment periods were separated by a 56-day wash-out interval. Blood sampling was conducted until 672 h after drug administration. Plasma teriflunomide (active metabolite of leflunomide) concentrations were determined, and pharmacokinetic parameters were calculated. Bioequivalence was evaluated using an ANOVA model, based on the AUCt and the Cmax after administration of leflunomide tablets. Bioequivalence was defined as the 90% confidence intervals (CIs) of the geometric mean ratios (GMRs) of AUCt and Cmax for the test and reference drugs being within the range of 0.80-1.25. The GMRs (90% CI) for AUCt and Cmax were 0.9506 (0.9091-0.9941) and 0.9861 (0.9360-1.0389), respectively, in the 10 mg study, and 0.9524 (0.9101-0.9968) and 0.9740 (0.9314-1.0186), respectively, in the 20 mg study. The 90% CIs of AUCt and Cmax at each dose were within the accepted range for bioequivalence. Based on the results, the test drug (CJ leflunomide) was bioequivalent to the commercially available reference drug (Arava®) at both doses.

Evaluation of bioequivalence of two enrofloxacin formulations after intramuscular administration in goats

Evaluation of bioequivalence of two enrofloxacin formulations after intramuscular administration in goats