Steady-state bioequivalence 2-way crossover study of two quetiapine prolonged-release 400 mg tablet formulations in normal male and female healthy subjects under fasting conditions
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OBJECTIVE: The purpose of this study was to assess bioequivalence between a generic and a brand quetiapine 400 mg prolonged-release (PR) formulation (Pharmathen S.A.; AstraZeneca Seroquel Prolong®<) in healthy volunteers under steady-state conditions. METHODS: Randomized, open-label, steady-state, 2-way crossover design in 48 subjects under fasting conditions. As a quetiapine dose of 400 mg was suspected to be high when administered to healthy subjects, we proceeded with an innovative design where subjects were titrated up using 150 mg, 200 mg, and 300 mg daily doses; first treatment (days 4 - 9) and second treatment (days 10 - 15), and then a tapering down phase (days 16 - 17). Blood samples were collected in EDTA K2< tubes prior to each dosing and over a 24-hour sampling schedule on days 9 and 15. Quetiapine was measured in plasma using LC-MS/MS assay (range 2.5 - 2,000 ng/mL). Pharmacokinetic analyses were performed using non-compartmental method to evaluate AUC>τ, C_max, and C_min. ANOVA was performed on the ln-transformed data and 90% confidence interval (90% CI) was determined. Bioequivalence was concluded if the 90% CI of AUC_τ, C_min, and C_max fell within 80.00 - 125.00%. RESULTS: 46 volunteers completed the study and were included in the analyses. Arithmetic mean (SD) for AUCτ were 7,161.18 (3,687.10) ng×h/mL and 7,184.27 (3,304.29) ng×h/mL, Cmax were 595.61 (345.98) ng/mL and 597.06 (253.67) ng/mL, and Cmin were 119.47 (84.24) ng/mL and 124.22 (137.68) ng/mL, respectively, for the test and reference. All pharmacokinetic parameters met the acceptance criteria as the 90% CI felt within 95.98 - 104.21%, 91.48 - 105.89%, and 86.32 - 104.49% for AUCτ, Cmax, and Cmin, respectively. Both formulations were well tolerated and no serious adverse events were reported. CONCLUSION: Our innovative design allowed safe administration of quetiapine 400 mg PR daily doses to healthy volunteers. Both Pharmathen and AstraZeneca formulations were well tolerated and bioequivalent under steady-state conditions.
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Large-scale retrospective evaluation of regulated liquid chromatography-mass spectrometry bioanalysis projects using different total error approaches.

The current approach in regulated LC-MS bioanalysis, which evaluates the precision and trueness of an assay separately, has long been criticized for inadequate balancing of lab-customer risks. Accordingly, different total error approaches have been proposed. The aims of this research were to evaluate the aforementioned risks in reality and the difference among four common total error approaches (ß-expectation, ß-content, uncertainty, and risk profile) through retrospective analysis of regulated LC-MS projects. Twenty-eight projects (14 validations and 14 productions) were randomly selected from two GLP bioanalytical laboratories, which represent a wide variety of assays. The results show that the risk of accepting unacceptable batches did exist with the current approach (9% and 4% of the evaluated QC levels failed for validation and production, respectively). The fact that the risk was not wide-spread was only because the precision and bias of modern LC-MS assays are usually much better than the minimum regulatory requirements. Despite minor differences in magnitude, very similar accuracy profiles and/or conclusions were obtained from the four different total error approaches. High correlation was even observed in the width of bias intervals. For example, the mean width of SFSTP's ß-expectation is 1.10-fold (CV=7.6%) of that of Saffaj-Ihssane's uncertainty approach, while the latter is 1.13-fold (CV=6.0%) of that of Hoffman-Kringle's ß-content approach. To conclude, the risk of accepting unacceptable batches was real with the current approach, suggesting that total error approaches should be used instead. Moreover, any of the four total error approaches may be used because of their overall similarity. Lastly, the difficulties/obstacles associated with the application of total error approaches in routine analysis and their desirable future improvements are discussed.

Some unnecessary or inadequate common practices in regulated LC-MS bioanalysis.

The global bioanalytical community increasingly craves scientifically sound practices and guidance where the rationale is given for each requirement. To this end, it is critical to first evaluate all the existing practices and requirements based on scientific findings and critical thinking. Here we are challenging several important common practices in regulated LC-MS bioanalysis, from the requirement of at least six different calibration concentrations, no extrapolation, use of blank and zero standard in each batch, selection of quality controls, to the way matrix effect and dilution integrity are being validated. Both the reasons why these common practices are unnecessary or inadequate and the potential solutions are presented.

Impact of calibrator concentrations and their distribution on accuracy of quadratic regression for liquid chromatography-mass spectrometry bioanalysis.

Despite the common use of quadratic regression in LC-MS bioanalysis, how calibrator concentrations should be determined is still vague. Both the number and concentrations of calibrators are usually selected arbitrarily to each one's preference. The purposes of this research were to evaluate the impact of calibrator concentrations and to find new approaches with improved accuracy and reduced cost for LC-MS bioanalysis. It was found for the first time that the lower and upper limits of quantitation plus their geometric mean are the three critical concentrations for quadratic regression. When different concentration ranges, different response precisions, and various degrees of downward quadratic responses were simulated, the best accuracy was obtained by including these critical concentrations and using fewer calibrator concentrations with more replicates per concentration, instead of using more calibrator concentrations in duplicate. In many cases, when the aforementioned three concentrations are used, as few as two replicates per concentration are enough for routine use and up to 20% of time and cost can be saved. Furthermore, downward quadratic response should be eliminated or reduced as much as possible and upper limit quality control must be included in each batch to monitor the accuracy at the high concentration end. The retrospective data analysis of published experimental results corroborates the aforementioned findings. Finally, the typical "concerns" and potential applications of the new quadratic regression approaches are discussed.

Comparison of two-concentration with multi-concentration linear regressions: Retrospective data analysis of multiple regulated LC-MS bioanalytical projects.

Linear calibration is usually performed using eight to ten calibration concentration levels in regulated LC-MS bioanalysis because a minimum of six are specified in regulatory guidelines. However, we have previously reported that two-concentration linear calibration is as reliable as or even better than using multiple concentrations. The purpose of this research is to compare two-concentration with multiple-concentration linear calibration through retrospective data analysis of multiple bioanalytical projects that were conducted in an independent regulated bioanalytical laboratory. A total of 12 bioanalytical projects were randomly selected: two validations and two studies for each of the three most commonly used types of sample extraction methods (protein precipitation, liquid-liquid extraction, solid-phase extraction). When the existing data were retrospectively linearly regressed using only the lowest and the highest concentration levels, no extra batch failure/QC rejection was observed and the differences in accuracy and precision between the original multi-concentration regression and the new two-concentration linear regression are negligible. Specifically, the differences in overall mean apparent bias (square root of mean individual bias squares) are within the ranges of -0.3% to 0.7% and 0.1-0.7% for the validations and studies, respectively. The differences in mean QC concentrations are within the ranges of -0.6% to 1.8% and -0.8% to 2.5% for the validations and studies, respectively. The differences in %CV are within the ranges of -0.7% to 0.9% and -0.3% to 0.6% for the validations and studies, respectively. The average differences in study sample concentrations are within the range of -0.8% to 2.3%. With two-concentration linear regression, an average of 13% of time and cost could have been saved for each batch together with 53% of saving in the lead-in for each project (the preparation of working standard solutions, spiking, and aliquoting). Furthermore, examples are given as how to evaluate the linearity over the entire concentration range when only two concentration levels are used for linear regression. To conclude, two-concentration linear regression is accurate and robust enough for routine use in regulated LC-MS bioanalysis and it significantly saves time and cost as well.

Comparison of different linear calibration approaches for LC-MS bioanalysis.

Many different calibration approaches are used for linear calibration in LC-MS bioanalysis, such as different numbers of concentration levels and replicates. However, direct comparison of these approaches is rare, particularly using experimental results. The purpose of this research is to compare different linear calibration approaches (existing and new ones) through simulations and experiments. Both simulation and experimental results demonstrate that linear calibration using two concentrations (two true concentrations, not forced through zero) is as good as or even better than that using multiple concentrations (e.g. 8 or 10) in terms of accuracy. Additionally, two-concentration calibration not only significantly saves time and cost, but is also more robust. Furthermore, it has been demonstrated that the extrapolation of a linear curve at the high concentration end to a linearity-known region is acceptable. When multi-concentration calibration is used, the difference between the two commonly used approaches, i.e. singlet (one curve) or duplicate (two curves) standards per concentration level is small when a method is very precise. Otherwise, one curve approach can result in larger variation at the low concentration end and higher batch failure rate. To reduce the variation and unnecessary reassays due to batch failure or possible rejection of the lowest and/or highest calibration standards, a partially duplicate-standard approach is proposed, which has duplicate-standard-like performance but still saves time and cost as singlet-standard approach does. Finally, the maximum allowable degrees of quadratic (non-linear) response in linear calibration are determined for different scenarios. Because of its multiple advantages and potential application in regulated bioanalysis, recommendations as how to implement two-concentration linear calibration in practice are given and some typical "concerns" regarding linear calibration using only two concentrations are addressed, e.g. how does one know if the response is truly linear over a given range when only two concentrations are used?.

Single-dose, 2-way crossover, bioequivalence study of two rosuvastatin formulations in normal healthy subjects under fasting conditions.

BACKGROUND: Rosuvastatin, a synthetic lipid-lowering agent acts selectively by competitive inhibition of 3-hydroxy- 3-methylglutaryl-coenzyme A. It is indicated as an adjunct to diet in patients with hypercholesterolemia and mixed dyslipidemia. OBJECTIVE: The purpose of this study was to demonstrate bioequivalence between a generic rosuvastatin 40 mg tablet (Zentiva, Prague, Czech Republic) and a reference product (Crestor, AstraZeneca, Luton, UK), under fasting conditions as required by the European Medicinal Agency. METHODS: A single-oral 40 mg-dose, randomized, open-label, 2-way crossover design study was conducted in 42 healthy volunteers under fasting conditions. Rosuvastatin was administered following an overnight-fast in two occasions with a 14-day washout period in-between. Blood samples were collected in EDTA-K2 tubes prior to dosing and over a 96-hour period. Rosuvastatin was measured in plasma using an automated LC-MS/MS assay (range 81.02 - 40,512.00 pg/ml). Pharmacokinetics were performed using non-compartmental analyses approach to evaluate AUC(last), AUC∞ and C(max). ANOVA was performed on the ln-transformed data and the 90% Confidence Interval (CI) was determined. Bioequivalence will be concluded if the 90% CI falls within 80.00 - 125.00% for AUC(last) and C(max). Safety and tolerability were also evaluated. RESULTS: 39 volunteers completed the study and were considered for the pharmacokinetic and statistical analyses. Descriptive safety data analyses were performed on all subjects. All pharmacokinetic parameters met the acceptance criteria as the 90% CI were within 80.00 - 125.00%. Both formulations were well tolerated and no serious adverse events were reported. CONCLUSION: This study showed that the test and reference products met the regulatory criteria for bioequivalence following a 40 mg oral dose under fasting conditions.

Truncated areas under the curve in the assessment of pioglitazone bioequivalence. Data from a single-center, single-dose, randomized, open-label, 2-way cross-over bioequivalence study of two formulations of pioglitazone 45 mg tablets under fasting conditions.

BACKGROUND: Pioglitazone (CAS 112529-15-4 for the HCl form) is an oral antidiabetic agent that is a member of the group of drugs known as thiazolidinediones. It is indicated for the treatment of type 2 diabetes mellitus. OBJECTIVE: The aim of this study was to assess the bioequivalence of a new pioglitazone 45 mg formulation (test formulation) vs. the reference product, as required by European regulatory authorities for the marketing of a generic product. Additionally, the applicability of the truncated area under the plasma concentration curve (AUC) approach to this drug and under these test conditions was determined. METHODS: This was a single-center, randomized, single-dose, open-label, 2-way crossover study in healthy volunteers under fasting conditions. Plasma samples were collected up to 120 h post-dosing. Pioglitazone and hydroxypioglitazone plasma levels were determined by reverse liquid chromatography and by tandem mass spectrometry detection (LC-MS/MS). Pharmacokinetic parameters were calculated using non-compartmental analysis. Area under the concentration-time curve from time zero to time of last non-zero concentration (AUC(last)) and maximum observed concentration (C(max)) were the main evaluation criteria, while the area under the concentration-time curve from time zero to infinity (AUC(inf)) was also analyzed for additional information. For the assessment of the applicability of the truncated AUC approach, AUCs truncated at 24, 48, 72, 96, and 120 h were calculated. All of the abovementioned pharmacokinetic parameters were analyzed using 90% geometric confidence interval of the ratio (T/R) of least-squares means from the ANOVA of the In-transformed parameter. Tolerability was monitored using physical examination, including vital sign measurements and laboratory analysis. RESULTS: According to the classical approach, the 90% geometric confidence intervals obtained by ANOVA for AUC(last), C(max) and AUC(inf) were within the predefined ranges (80-125%) for both analytes. Truncated AUCs were also in all cases within the predefined ranges for acceptance of bioequivalence (e.g. 90% confidence interval). CONCLUSION: Bioequivalence between test and reference formulations, both in terms of rate and extension of absorption, under fasting conditions was concluded according to European guidelines. Both formulations were well tolerated. The conclusion of bioequivalence was also supported using the truncated AUCs approach.

Results of a single-center, single-dose, randomized-sequence, open-label, two-way crossover bioequivalence study of two formulations of valsartan 160-mg tablets in healthy volunteers under fasting conditions.

BACKGROUND: Valsartan is a nonpeptide, orally active angiotensin II type 1 receptor blocker used to treat hypertension alone or in combination with other antihypertensive agents. OBJECTIVE: The aim of this study was to compare the relative bioavailability of a new valsartan 160-mg formulation (ie, test drug) and that of a reference formulation so that bioequivalence could be assessed, as required by European regulatory authorities for the marketing of a generic product. METHODS: This was a single-center, single-dose, randomized-sequence, open-label, 2-way crossover study with a minimum washout period of 7 days; drug was administered to healthy volunteers under fasting conditions. Blood samples were collected up to 36 hours postadministration, and valsartan levels were gauged from plasma by reverse liquid chromatography and tandem mass spectrometry detection (ie, the LC-MS/MS method). Pharmacokinetic parameters were calculated from valsartan concentration data using noncompartmental analysis. AUC(last), AUC(infinity), and C(max) were analyzed. The 90% CIs of the ratios of the test-versus-reference pharmacokinetic parameters (AUC(last), AUC(infinity), and C(max)) were obtained by ANOVA on ln-transformed data. The 90% CIs were required to be within 80.00% to 125.00% of the 90% CI to meet the criteria for bioequivalence. Tolerability was monitored using physical examination (including vital-sign measurements) and ECG performed at screening, as well as laboratory analysis, including biochemistry tests, hematology tests, and urinalysis, which were performed at screening and during the study period. RESULTS: Thirty-eight white (90.5%), 2 black (4.8%), and 2 Hispanic subjects (4.8%) enrolled in the study; the sample included a total of 27 men and 15 women. The mean (SD) age was 37 (11) years and mean weight was 65.4 (7.6) kg. The 90% CI values for pharmacokinetic measurements were as follows: AUC(last), 94.45% to 118.59%; AUC(infinity), 93.58% to 116.51%; and C(max), 93.61% to 122.02%. Thus, they were all within the predefined 80.00% to 125.00% range. Thirty-six postadministration adverse events were reported; the most common was blood pressure decrease. A decrease of blood pressure was experienced by 6 subjects (14.6%) after the administration of the test formulation, and by 5 subjects (12.5%) after the administration of the reference formulation. Thirty-three of these adverse events were graded as mild and 3 as moderate; 11 were judged as probably related, 12 as possibly related, 3 as remotely related, and 10 as unrelated to the study medication. CONCLUSIONS: In this open-label study of healthy volunteers, the test and reference formulations of valsartan 160 mg met the European regulatory definition of bioequivalence, based on the rate and extent of absorption of a single dose under fasting conditions. Both formulations were well tolerated.

Bioequivalence study of two enteric-coated formulations of pantoprazole in healthy volunteers under fed conditions.

This study was conducted in order to assess the bioequivalence of two enteric-coated formulations of 40 mg pantoprazole (CAS 102625-70-7), under fed conditions. Seventy-four healthy subjects, age ranging from 24 to 55 years, were enrolled in a two-centre, randomised, single-dose, open-label, 2-way crossover study, with a minimum washout period of 7 days. Plasma samples were collected up to 30.0 h post-dosing. Pantoprazole levels were determined by reverse liquid chromatography and detected by tandem mass spectrometry detection (LC-MS/ MS). Pharmacokinetic parameters used for bioequivalence assessment were the AUClast (area under the concentration-time curve from time zero to time of last observed non-zero concentration), AUCinf (area under the concentration-time curve from time zero to infinity) and Cmax, (maximum observed concentration). These parameters were determined from the pantoprazole concentration data using non-compartmental analysis. Gender-related differences were found in the variability of all relevant pharmacokinetic parameters. The 90% CI (90% confidence intervals), obtained by analysis of variance (ANOVA) were within the predefined ranges. Bioequivalence between the test and reference formulation, under fed conditions, was concluded both in terms of rate and extent of absorption.

Bioequivalence study of two letrozole tablet formulations. Single dose, randomized, open-label, two-way crossover bioequivalence study of letrozole 2.5 mg tablets in healthy volunteers under fasting conditions.

The study was conducted in order to compare the bioavailability of two tablet formulations containing letrozole 2.5 mg (CAS 112809-51-5). Twenty healthy subjects were enrolled in a single-centre, bioequivalence, randomised, single-dose, open-label, two-way crossover study, performed under fasting conditions with a minimum washout period of 21 days. Plasma samples were collected up to 240 h post-dosing. Letrozole levels were determined by reverse liquid chromatography and detected by tandem mass spectrometry detection, LC/MS/MS method. Pharmacokinetic parameters used for bioequivalence assessment, area under the concentration-time curve from time zero to time of last non-zero concentration (AUC(0-t)) and from time zero to infinitive (AUC(0-inf)) and maximum observed concentration (Cmax), were determined from the letrozole concentration data using non-compartmental analysis. The 90% confidence intervals obtained by analysis of variance were 90% geometric confidence Intervals of the ratio (A/B) of least-squares means from the analysis of variance (ANOVA) of the In-transformed AUC(0-t), and Cmax was within 80% to 125%. Bloequivalence between formulations was concluded both in terms of rate and extent of absorption.

Truncated AUCs in the assessment of the bioequivalence of topiramate, a long half-life drug.

This study was conducted in order to assess the bioequivalence of two tablet formulations containing topiramate (CAS 97240-79-4), 25 mg. Twenty-four healthy volunteers were enrolled in an open-label, randomised, crossover, 2 periods x 2 sequences, with a minimum washout period of 21 days, single dose study. Blood samples were collected prior to study drug administration and 0.167, 0.333, 0.500, 0.667, 1.00, 1.33, 1.67, 2.00, 2.50, 3.00, 4.00, 6.00, 8.00, 12.0, 24.0, 48.0, 96.0, 144, 192, and 264 h post-dose in each period. Plasma levels of topiramate from the 23 subjects who completed the study, were determined by high-pressure liquid chromatography with tandem mass detection, HPLC/MS/MS (lower limit of quantification 9.98 ng/mL). Pharmacokinetic parameters used for bioequivalence assessment (AUC(last), AUC(inf) and C(max)) were determined from the plasma concentration data using non-compartmental analysis. Mean +/- standard deviation elimination half-life for the reference formulation was 84.18 +/- 14.61h whereas for the test formulation it was 80.82 +/- 11.50h. The 90% Confidence Intervals (90 CI) were 98.00-111.35% for C(max), 98.44-103.76% for AUC(last) and 96.61-103.00% for AUC(inf), that is, within the ranges defined in the protocol for acceptance of bioequivalence. The 90 CIs obtained for the truncated AUCs were as follows: 100.27-105.32% for AUC0-48, 99.28-104.62% for AUC0-48, 99.13-104.56% for AUC0-96, 95.67-104.82% for AUC0-144, and 100.04-103.76% for AUC0-192. Both analysed formulations are bioequivalent irrespective of whether the conventional or truncated AUC approach is used. This study demonstrated that topiramate can be viewed as a long half-life drug and that the truncated AUC ap proach could be considered for bioequivalence assessment.