ABCG2 polymorphism and rivaroxaban pharmacokinetics in healthy individuals after a single dose.

Rivaroxaban is a direct factor Xa inhibitor. Its interindividual variability is large and may be connected to the occurrence of adverse drug reactions or drug inefficacy. Pharmacogenetics studies concentrating on the reasons underlying rivaroxaban's inadequate response could help explain the differences in treatment results and medication safety profiles. Against this background, this study evaluated whether polymorphisms in the gene encoding the ABCG2 transporter modify the pharmacokinetic characteristics of rivaroxaban. A total of 117 healthy volunteers participated in two bioequivalence experiments with a single oral dose of 20 mg rivaroxaban, with one group fasting and the other being fed. Ultra-high-performance liquid chromatography coupled with mass spectrometry was employed to determine the plasma concentrations of rivaroxaban, and the WinNonlin program was used to calculate the pharmacokinetics parameters. In the fasting group, the rivaroxaban pharmacokinetic parameters of Vd (508.27 vs 334.45 vs 275.59 L) and t1/2 (41.04 vs 16.43 vs 15.47 h) were significantly higher in ABCG2 421 A/A genotype carriers than in ABCG2 421 C/C and 421 C/A genotype carriers (P<0.05). The mean values of Cmax (145.81 vs 176.27 vs 190.19 ng/mL), AUC0-t (1193.81 vs 1374.69 vs 1570.77 ng/mL·h), and Cl (11.82 vs 14.50 vs 13.01 mL/h) for these groups were lower, but this difference was not statistically significant (P>0.05). These findings suggested that the ABCG2 421 A/A genotype may impact rivaroxaban parameters after a single dose in healthy subjects. This finding must be validated before it is applied in clinical practice.

Efficacy, safety and immunogenicity of the biosimilar etanercept compared to the reference formulation original etanercept in patients with rheumatoid arthritis: An open-label, randomized, comparative, multicenter study.

BACKGROUND: The objective of this phase III clinical randomized trial was to establish the therapeutic equivalence of biosimilar etanercept (bio-etanercept) with original etanercept (O-etanercept) for patients diagnosed with rheumatoid arthritis. METHODS: The study (NCT04079374) enrolled patients with moderate to high disease activity rheumatoid arthritis. Enrolled patients were randomized 1:1 into 2 treatment groups, 1 receiving bio-etanercept (study drug) and the other receiving O-etanercept (comparator) at a dose of 25mg twice weekly, for 24 weeks. The primary efficacy endpoint was the number of patients with an ACR20 response after 24 weeks of treatment. Safety (adverse reaction/adverse event) and immunogenicity of both drugs were evaluated. RESULTS: Among 156 patients (79 in the bio-etanercept group and 77 in the O-etanercept group) who completed 24-week treatment and 4-week follow-up, 82.3% (65 patients) and 90.9% (70 patients) achieved an ACR20 response in the bio-etanercept and O-etanercept groups, respectively. There was no significant difference between the 2 groups (P = .16). No significant differences in the occurrence of adverse reactions/adverse events were found between the 2 groups regardless of severity (P = .63 for mild, P = .43 for moderate and P > .99 for severe). The development of antibodies in the bio-etanercept group was observed in 4 (5.1%; visit 6), 4 (5.0%; visit 9), and 3 (3.8%; visit 11) patients, and in 5 (6.4%), 5 (6.5%), and 3 (4.1%) patients in the O-etanercept group. The differences between the 2 groups were not significant (P > .99). CONCLUSIONS: This study showed that bio-etanercept was equivalent to the reference formulation.

Sample Size Determination and Study Design Impact on Dose-Scale Pharmacodynamic Bioequivalence: a Case Study Using Orlistat.

Dose-scale pharmacodynamic bioequivalence is recommended for evaluating the consistency of generic and innovator formulations of certain locally acting drugs, such as orlistat. This study aimed to investigate the standard methodology for sample size determination and the impact of study design on dose-scale pharmacodynamic bioequivalence using orlistat as the model drug. A population pharmacodynamic model of orlistat was developed using NONMEM 7.5.1 and utilized for subsequent simulations. Three different study designs were evaluated across various predefined relative bioavailability ratios of test/reference (T/R) formulations. These designs included Study Design 1 (2×1 crossover with T1 60 mg, R1 60 mg, and R2 120 mg), Study Design 2 (2×1 crossover with T2 120 mg, R1 60 mg, and R2 120 mg), and Study Design 3 (2×2 crossover with T1 60 mg, T2 120 mg, R1 60 mg, and R2 120 mg). Sample sizes were determined using a stochastic simulation and estimation approach. Under the same T/R ratio and power, Study Design 3 required the minimum sample size for bioequivalence, followed by Study Design 1, while Study Design 2 performed the worst. For Study Designs 1 and 3, a larger sample size was needed on the T/R ratio < 1.0 side for the same power compared to that on the T/R ratio > 1.0 side. The opposite asymmetry was observed for Study Design 2. We demonstrated that Study Design 3 is most effective for reducing the sample size for orlistat bioequivalence studies, and the impact of T/R ratio on sample size shows asymmetry.

Pharmacokinetics and Safety of Estradiol Valerate Tablet and Its Generic: A Phase 1 Bioequivalence Study in Healthy Chinese Postmenopausal Female Subjects.

Purpose: Estradiol valerate (Progynova®) is used as hormone therapy to supplement estrogen deficiency. This study aimed to assess the bioequivalence of an estradiol valerate tablet and its generic form, under fasting and fed conditions. Methods: A randomized, open-label, single-dose, 2-period crossover study was conducted on healthy postmenopausal Chinese female volunteers under fasting and fed conditions. For each period, the subjects received either a 1 mg tablet of estradiol valerate or its generic. Blood samples were collected before dosing and up to 72 hours after administration. Plasma levels of total estrone, estradiol, and unconjugated estrone were quantified using a validated liquid chromatography-tandem mass spectrometry method. Results: A total of 54 volunteers were enrolled in this study. The primary pharmacokinetic parameters, including Cmax, AUC0-t, and AUC0-∞, were similar for the two drugs under both fasting and fed conditions, with 90% confidence intervals for the geometric mean ratios of these parameters, all meeting the bioequivalence criterion of 80-125%. A total of 48 adverse events (AEs) were reported in the fed study compared with 24 AEs in the fasting study. Conclusion: Estradiol valerate and its generic form were bioequivalent and well tolerated under both fasting and fed conditions.

Topical Semisolid Drug Product Critical Quality Attributes with Relevance to Cutaneous Bioavailability and Pharmacokinetics: Part I-Bioequivalence of Acyclovir Topical Creams.

PURPOSE: To develop a toolkit of test methods for characterizing potentially critical quality attributes (CQAs) of topical semisolid products and to evaluate how CQAs influence the rate and extent of active ingredient bioavailability (BA) by monitoring cutaneous pharmacokinetics (PK) using an In Vitro Permeation Test (IVPT). METHODS: Product attributes representing the physicochemical and structural (Q3) arrangement of matter, such as attributes of particles and globules, were assessed for a set of test acyclovir creams (Aciclostad® and Acyclovir 1A Pharma) and compared to a set of reference acyclovir creams (Zovirax® US, Zovirax® UK and Zovirax® Australia). IVPT studies were performed with all these creams using heat-separated human epidermis, evaluated with both, static Franz-type diffusion cells and a flow through diffusion cell system. RESULTS: A toolkit developed to characterize quality and performance attributes of these acyclovir topical cream products identified certain differences in the Q3 attributes and the cutaneous PK of acyclovir between the test and reference sets of products. The cutaneous BA of acyclovir from the set of reference creams was substantially higher than from the set of test creams. CONCLUSIONS: This research elucidates how differences in the composition or manufacturing of product formulations can alter Q3 attributes that modulate myriad aspects of topical product performance. The results demonstrate the importance of understanding the Q3 attributes of topical semisolid drug products, and of developing appropriate product characterization tests. The toolkit developed here can be utilized to guide topical product development, and to mitigate the risk of differences in product performance, thereby supporting a demonstration of bioequivalence (BE) for prospective topical generic products and reducing the reliance on comparative clinical endpoint BE studies.

Bioequivalence study of low dose drospirenone/ethinyl estradiol 3 mg/0.03 mg film tablets under fasting conditions in Turkish healthy female subjects.

This bioequivalence research aims to evaluate the relative bioavailability and pharmacokinetic characteristics of ethinyl estradiol and drospirenone in the test preparation in comparison to the reference preparation during fasting conditions. A liquid chromatography method with tandem mass spectrometry was used to determine the concentrations of drospirenone and ethinyl estradiol in plasma. The pharmacokinetic parameters that were analyzed were the maximum plasma concentration (Cmax), time to achieve Cmax (tmax), elimination half life, and area under the concentration time curve of plasma (AUC0-t, AUC0-∞ for ethinyl estradiol, and AUC0-72h for drospirenone). Both the AUC and Cmax parameters were determined to be between 80.00% and 125.00% (90% confidence intervals), which is the acceptable range. Based on the study findings, it was concluded that the test formulation, which includes 3 mg of drospirenone and 0.03 mg of ethinyl estradiol, demonstrated bioequivalence when compared to the reference formulation.

Investigating the Bioavailability and Insulin-like Growth Factor-I Release of Two Different Strengths of Somapacitan: A Randomised, Double-Blind Crossover Trial.

STUDY DESIGN AND OBJECTIVE: Randomised, double-blind, crossover trial to confirm bioequivalence of somapacitan, a long-acting growth hormone (GH), in 5 mg/1.5 mL and 10 mg/1.5 mL strengths in equimolar doses. METHODS: Healthy participants were randomised (1:1:1) to subcutaneous somapacitan treatment in one dosing period with 5 mg/1.5 mL and two periods with 10 mg/1.5 mL. Eligibility criteria included age 18-45 years and body mass index 18.5-24.9 kg/m2. Exclusion criteria included history of GH deficiency, previous GH treatment, weight > 100.0 kg and participation in any clinical trial of an investigational medicinal product within 45 days or five times the half-life of the previous investigational product before screening. Area under the curve from time 0 until last quantifiable observation (AUC0-t), maximum serum concentration (Cmax), time to Cmax and terminal half-life of somapacitan and safety were assessed. RESULTS: In total, 33 participants were randomised. For AUC0-t, estimated treatment ratio (ETR) (5 mg/1.5 mL versus 10 mg/1.5 mL) was 0.95 (90% confidence interval [CI] 0.89-1.01). Point estimate and 90% CIs were within the acceptance range (0.80-1.25). For Cmax, ETR was 0.77 (90% CI 0.68-0.89). Point estimate and 90% CIs were outside the acceptance range (0.80-1.25). Mean insulin-like growth factor-I (IGF-I) and IGF-I standard deviation score concentration-time curves for each strength were almost identical. No new safety issues were identified. CONCLUSIONS: Bioequivalence criterion for somapacitan 5 mg/1.5 mL and 10 mg/1.5 mL was met for AUC0-t but not for Cmax. The two strengths had equivalent IGF-I responses. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03905850 (3 April 2019).

Somapacitan is a long-acting growth hormone used to treat people with growth hormone deficiency. Somapacitan is injected under the skin with an injection pen. The dose is based on a person's body weight and how they respond to treatment. We compared two strengths of injection pen, containing either 5 or 10 mg of somapacitan per 1.5 mL. For both strengths, participants were given the same dose. We wanted to understand whether the body absorbs these different strengths into the bloodstream in the same way. We also measured levels of insulin-like growth factor-I (IGF-I), a hormone formed when growth hormone is present in the blood, to see the effect of different strengths of somapacitan on the body. In our study, 33 healthy adults received one round of injection using the somapacitan 5 mg pen and two rounds using the somapacitan 10 mg pen, all at least 3 weeks apart. We found no differences in the amount of somapacitan being absorbed into the bloodstream, nor how fast it was absorbed. The peak amount of somapacitan in the bloodstream was higher in people using the 10 mg pen. There were no differences in IGF-I levels following use of either injection pen. Overall, our results show both strengths of somapacitan lead to similar responses in the body. Having different strength options could allow doctors to adjust the dose of somapacitan more easily, depending on a patient's response to treatment.

Establishing Virtual Bioequivalence and Clinically Relevant Specifications for Omeprazole Enteric-Coated Capsules by Incorporating Dissolution Data in PBPK Modeling.

Currently, Biopharmaceutics Classification System (BCS) classes I and III are the only biological exemptions of immediate-release solid oral dosage forms eligible for regulatory approval. However, through virtual bioequivalence (VBE) studies, BCS class II drugs may qualify for biological exemptions if reliable and validated modeling is used. Here, we sought to establish physiologically based pharmacokinetic (PBPK) models, in vitro-in vivo relationship (IVIVR), and VBE models for enteric-coated omeprazole capsules, to establish a clinically-relevant dissolution specification (CRDS) for screening BE and non-BE batches, and to ultimately develop evaluation criteria for generic omeprazole enteric-coated capsules. To establish omeprazole's IVIVR based on the PBPK model, we explored its in vitro dissolution conditions and then combined in vitro dissolution profile studies with in vivo clinical trials. The predicted omeprazole pharmacokinetics (PK) profiles and parameters closely matched the observed PK data. Based on the VBE results, the bioequivalence study of omeprazole enteric-coated capsules required at least 48 healthy Chinese subjects. Based on the CRDS, the capsules' in vitro dissolution should not be < 28%-54%, < 52%, or < 80% after two, three, and six hours, respectively. Failure to meet these dissolution criteria may result in non-bioequivalence. Here, PBPK modeling and IVIVR methods were used to bridge the in vitro dissolution of the drug with in vivo PK to establish the BE safety space of omeprazole enteric-coated capsules. The strategy used in this study can be applied in BE studies of other BCS II generics to obtain biological exemptions and accelerate drug development.

Pharmacokinetics and Bioequivalence of Apremilast Tablets in Chinese Healthy Subjects Under Fasting and Postprandial States.

Objective: This study compared the pharmacokinetics, safety and bioequivalence (BE) of generic and original apremilast tablets in healthy Chinese subjects under fasting and postprandial conditions, providing sufficient evidence for abbreviated new drug application. Methods: A randomized, open-label, two-formulation, single-dose, two-period crossover pharmacokinetic study was performed. Thirty-two eligible healthy Chinese subjects were enrolled in fasting and postprandial studies, respectively. In each trial, subjects received a single 30-mg dose of the test or reference apremilast tablet, followed by a 7-day washout interval between periods. Serial blood samples were obtained for up to 48 h post-intake in each period, and the plasma concentrations of apremilast were determined by a validated method. The primary pharmacokinetic (PK) parameters, including the maximum plasma concentration (Cmax), the areas under the plasma concentration-time curve (AUC0-t, AUC0-∞), were calculated using the non-compartmental method. The geometric mean ratios of the two formulations and the corresponding 90% confidence intervals (CIs) were acquired for bioequivalence analysis. The safety of both formulations was also evaluated. Results: Under fasting and postprandial states, the PK parameters of the test drug were similar to those of the reference drug. The 90% CIs of the geometric mean ratios of the test to reference formulations were 94.09-103.44% for Cmax, 94.05-103.51% for AUC0-t, and 94.56-103.86% for AUC0-∞ under fasting conditions, and 99.18-112.48% for Cmax, 98.79-106.02% for AUC0-t, and 98.95-105.89% for AUC0-∞ under postprandial conditions, all of which were within the bioequivalence range of 80.00-125.00%. Both formulations were well tolerated, and no serious adverse events occurred during the study. Conclusion: The trial confirmed that the PK parameters of the generic and original apremilast tablets were bioequivalent in healthy Chinese subjects under fasting and postprandial states, which met the predetermined regulatory standards. Both formulations were safe and well tolerated. Clinical Trial Registration: chinaDrugtrials.org.cn, identifier CTR20191056 (July 30, 2019); chictr.org.cn, identifier ChiCTR2300076806 (October 19, 2023).

Bioequivalence of a new coated 15 mg primaquine formulation for malaria elimination.

BACKGROUND: With only one 15 mg primaquine tablet registered by a stringent regulatory authority and marketed, more quality-assured primaquine is needed to meet the demands of malaria elimination. METHODS: A classic, two sequence, crossover study, with a 10-day wash out period, of 15 mg of IPCA-produced test primaquine tablets and 15 mg of Sanofi reference primaquine tablets was conducted. Healthy volunteers, aged 18-45 years, without glucose-6-phosphate dehydrogenase deficiency, a baseline haemoglobin ≥ 11 g/dL, creatinine clearance ≥ 70 mL/min/1.73 ms, and body mass index of 18.5-30 kg/m2 were randomized to either test or reference primaquine, administered on an empty stomach with 240 mL of water. Plasma primaquine and carboxyprimaquine concentrations were measured at baseline, then 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0, 2.333, 2.667, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 8.0, 10.0, 12.0, 16.0, 24.0, 36.0, 48.0 and 72.0 h by liquid chromatography coupled to tandem mass spectrometry. Primaquine pharmacokinetic profiles were evaluated by non-compartmental analysis and bioequivalence concluded if the 90% confidence intervals (CI) of geometric mean (GM) ratios of test vs. reference formulation for the peak concentrations (Cmax) and area under the drug concentration-time (AUC0-t) were within 80.00 to 125.00%. RESULTS: 47 of 50 volunteers, median age 33 years, completed both dosing rounds and were included in the bioequivalence analysis. For primaquine, GM Cmax values for test and reference formulations were 62.12 vs. 59.63 ng/mL, resulting in a GM ratio (90% CI) of 104.17% (96.92-111.96%); the corresponding GM AUC0-t values were 596.56 vs. 564.09 ngxh/mL, for a GM ratio of 105.76% (99.76-112.08%). Intra-subject coefficient of variation was 20.99% for Cmax and 16.83% for AUC0-t. Median clearances and volumes of distribution were similar between the test and reference products: 24.6 vs. 25.2 L/h, 189.4 vs. 191.0 L, whilst the median half-lives were the same, 5.2 h. CONCLUSION: IPCA primaquine was bioequivalent to the Sanofi primaquine. This opens the door to prequalification, registration in malaria endemic countries, and programmatic use for malaria elimination. Trial registration The trial registration reference is ISRCTN 54640699.

Physiologically Based Biopharmaceutics Modeling for Gefapixant IR Formulation Development and Defining the Bioequivalence Dissolution Safe Space.

Gefapixant is a weakly basic drug which has been formulated as an immediate release tablet for oral administration. A physiologically based biopharmaceutics model (PBBM) was developed based on gefapixant physicochemical properties and clinical pharmacokinetics to aid formulation selection, bioequivalence safe space assessment and dissolution specification settings. In vitro dissolution profiles of different free base and citrate salt formulations were used as an input to the model. The model was validated against the results of independent studies, which included a bioequivalence and a relative bioavailability study, as well as a human ADME study, all meeting acceptance criteria of prediction errors ≤ 20% for both Cmax and AUC.  PBBM was also applied to evaluate gastric pH-mediated drug-drug-interaction potential with co-administration of a proton pump inhibitor (PPI), omeprazole. Model results showed good agreement with clinical data in which omeprazole lowered gefapixant exposure for the free base formulation but did not significantly alter gefapixant pharmacokinetics for the citrate based commercial drug product. An extended virtual dissolution bioequivalence safe space was established.  Gefapixant drug product batches are anticipated to be bioequivalent with the clinical reference batch when their dissolution is > 80% in 60 minutes. PBBM established a wide dissolution bioequivalence space as part of assuring product quality.

Model-Based Bioequivalence Analysis to Assess and Predict the Relative Bioavailability of Valproic Acid Formulations.

BACKGROUND AND OBJECTIVE: Model-based bioequivalence (MBBE) encompasses the use of nonlinear mixed effect models supporting the estimation of pharmacokinetic endpoints to assess the relative bioavailability between multi-source drug products. This application emerges as a valuable alternative to the standard non-compartmental analysis (NCA) in bioequivalence (BE) studies in which dense sampling is not possible. In this work, we aimed to assess the application of MBBE compared to traditional methods in evaluating the relative bioavailability of two formulations with different drug release properties. Additionally, we sought to predict the performance of a modified-release formulation in a multiple-dose scenario, leveraging data from a single-dose study. METHODS: MBBE analysis was implemented to estimate the BE endpoints (90% CI for the Test/Reference geometric mean ratio, T/R GMR) in area under the concentration-time curve (AUC) and maximum concentration (Cmax) using data from a single-dose, 2-period, 2-sequence BE study performed in 14 healthy subjects between a locally developed valproic acid extended-release formulation (Test) and the brand-name delayed-release formulation (Reference). RESULTS: Results were compared with the standard approach, revealing that MBBE analysis achieved higher discrimination between formulations for Cmax, addressing limitations of the experimental sampling design and highlighting an advantage for this model-based analysis even when rich data are available. Additionally, the bioequivalence outcome under the multiple-dose scenario was predicted through a simulation-based study for both total and unbound valproic acid concentrations, considering the impact of valproic acid saturable binding on BE conclusions. CONCLUSIONS: The MBBE analysis was superior to the NCA approach in detecting product-related differences, overcoming limitations in the study experimental design. Predictions for the multiple-dose scenario preclude that the extended-release properties of the Test formulation would persist at steady state, resulting in lower peak-to-trough fluctuation and bioequivalent performance in terms of the extent of drug absorption. Overall, these results should discourage unnecessary experimentation in healthy subjects.

Quantitation of thiorphan in human plasma using LC-MS/MS and its application to a bioequivalence study.

Racecadotril, an anti-secretory medication, has been used as an adjuvant in an oral rehydration therapy for children experiencing severe diarrhea. Racecadotril is quickly converted to thiorphan, an active metabolite, after oral treatment, which mediates all subsequent activities. An efficient and rapid liquid chromatography-tandem mass spectrometry method was developed and fully validated to measure thiorphan in human plasma, using thiorphan-d7 as an internal standard. The extraction method used was protein precipitation while chromatographic separation was achieved using InertSil CN-3 (50 × 2.1 mm, 5 µm column). The assay was linear over the concentration range of 1-200 ng/ml with correlation coefficients of ≥0.9991. The intra- and inter-day precisions were less than 10.0 % for all concentrations investigated. 0.02 % aqueous formic acid and methanol (30:70 v: v) were used as mobile phases, with an analysis time of less than 1 min. This method proved stable under several conditions. The developed method worked well in a three-period pharmacokinetic bioequivalence study after a single oral administration of 100 mg racecadotril to 15 healthy Jordanian volunteers under fasting conditions.

Immunomodulation profile of the biosimilar trastuzumab MYL-1401O in a bioequivalence phase I study.

The initial Phase-I single centre, single dose, randomized, double-blind, cross-over study was planned to assess the pharmacokinetic and pharmacodynamic bioequivalence of the trastuzumab biosimilar (MYL-1401O) compared to the reference Herceptin®. Their respective immunomodulation profile presented in this paper involved healthy males receiving a single infusion of both monoclonals, separated by a washout period. Sixty parameters were assessed in total, including serum cytokines, peripheral mononuclear cell (PBMC) subsets, cell activation and response to recall antigens and mitogen, pre- and post- infusion, as well as a cytokine release assay (CRA) at baseline. Trastuzumab infusion induced a transient and weak peak of serum IL-6 at 6 h, and a modulation of mononuclear cell subset profile and activation level, notably CD16 + cells. Except for CD8 + T cells, there were no significant differences between Herceptin® and MYL-1401O. In CRA, PBMC stimulated with MYL-1401O or Herceptin® similarly secreted IL-6, TNF-α, IL-1ß, GM-CSF, IFN-γ, and IL-10, but no or low level of IL-2. Interestingly, some observed adverse events correlated with IL-2 and IFN-γ in CRA. MYL-1401O exhibited a very similar immunomodulation profile to Herceptin®, strongly supporting its bioequivalence. This approach may thus be included in a proof-of-concept study. CRA may be used as a predictive assay for the evaluation of clinical monoclonals.

Application of the Finite Absorption Time (F.A.T.) Concept in the Assessment of Bioequivalence.

PURPOSE: Το formulate a methodology for the assessment of bioequivalence using metrics, which are based on the physiologically sound F.A.T. METHODS: The equations of the physiologically based finite time pharmacokinetic models for the one-and two-compartment model with one and two input stages of absorption were solved to derive metrics for the extent and rate of absorption. Simulated data were used to study the proper way for the estimation of metrics. A bioequivalence study was analyzed using these metrics. RESULTS: The rate of drug absorption was found to be equal to the slope of the amount absorbed versus time curve. The amount of drug absorbed at the end of the absorption process, corresponding to the blood concentration at F.A.T. is an indicator of the extent of absorption. The plot of the ratio test/reference of the simulated data for the amount absorbed as a function of time becomes constant beyond the end of drug absorption from the formulation exhibiting the longer absorption. The assessment of the bioequivalence study was based on the slope of the amount absorbed versus time curve for the rate of absorption, while the estimate for the constant ratio test/reference for the amount absorbed was used for the assessment of extent of absorption. CONCLUSIONS: The assessment of rate in bioequivalence studies can be based on the estimation of slope of the percent absorbed versus time curve while the constant ratio test/reference for the amount of drug absorbed is an indicator of the extent of absorption.

Discovery and Model-Informed Drug Development of a Controlled-Release Formulation of Nonracemic Amisulpride that Reduces Plasma Exposure but Achieves Pharmacodynamic Bioequivalence in the Brain.

Nonracemic amisulpride (SEP-4199) is an investigational 85:15 ratio of aramisulpride to esamisulpride and currently in clinical trials for the treatment of bipolar depression. During testing of SEP-4199, a pharmacokinetic/pharmacodynamic (PK/PD) disconnect was discovered that prompted the development of a controlled-release (CR) formulation with improved therapeutic index for QT prolongation. Observations that supported the development of a CR formulation included (i) plasma concentrations of amisulpride enantiomers were cleared within 24-hours, but brain dopamine D2 receptor (D2R) occupancies, although achieving stable levels during this time, required 5 days to return to baseline; (ii) nonracemic amisulpride administered to non-human primates produced significantly greater D2R occupancies during a gradual 6-hour administration compared with a single bolus; (iii) concentration-occupancy curves were left-shifted in humans when nonracemic amisulpride was gradually administered over 3 and 6 hours compared with immediate delivery; (iv) CR solid oral dose formulations of nonracemic amisulpride were able to slow drug dissolution in vitro and reduce peak plasma exposures in vivo in human subjects. By mathematically solving for a drug distribution step into an effect compartment, and for binding to target receptors, the discovery of a novel PK/PD model (termed here as Distribution Model) accounted for hysteresis between plasma and brain, a lack of receptor saturation, and an absence of accumulation of drug occupancy with daily doses. The PK/PD disconnect solved by the Distribution Model provided model-informed drug development to continue in Phase III using the non-bioequivalent CR formulation with diminished QT prolongation as dose-equivalent to the immediate release (IR) formulation utilized in Phase II.

Model-based bioequivalence approach for sparse pharmacokinetic bioequivalence studies: Model selection or model averaging?

Conventional pharmacokinetic (PK) bioequivalence (BE) studies aim to compare the rate and extent of drug absorption from a test (T) and reference (R) product using non-compartmental analysis (NCA) and the two one-sided test (TOST). Recently published regulatory guidance recommends alternative model-based (MB) approaches for BE assessment when NCA is challenging, as for long-acting injectables and products which require sparse PK sampling. However, our previous research on MB-TOST approaches showed that model misspecification can lead to inflated type I error. The objective of this research was to compare the performance of model selection (MS) on R product arm data and model averaging (MA) from a pool of candidate structural PK models in MBBE studies with sparse sampling. Our simulation study was inspired by a real case BE study using a two-way crossover design. PK data were simulated using three structural models under the null hypothesis and one model under the alternative hypothesis. MB-TOST was applied either using each of the five candidate models or following MS and MA with or without the simulated model in the pool. Assuming T and R have the same PK model, our simulation shows that following MS and MA, MB-TOST controls type I error rates at or below 0.05 and attains similar or even higher power than when using the simulated model. Thus, we propose to use MS prior to MB-TOST for BE studies with sparse PK sampling and to consider MA when candidate models have similar Akaike information criterion.

Pharmacokinetics and safety of candidate tocilizumab biosimilar CT-P47 administered by auto-injector or pre-filled syringe: a randomized, open­label, single-dose phase I study.

BACKGROUND: This study compared the pharmacokinetics (PK), immunogenicity, and safety of candidate tocilizumab biosimilar, CT-P47, administered via auto-injector (CT-P47 AI) or pre-filled syringe (CT-P47 PFS), in healthy Asian adults. RESEARCH DESIGN AND METHODS: In this phase I, multicenter, open-label study, participants were randomized 1:1 to receive a single 162 mg/0.9 mL dose of CT-P47 via AI or PFS. Primary endpoints were area under the concentration - time curve from time zero to infinity (AUC0-inf) and maximum serum concentration (Cmax). PK equivalence was determined if 90% confidence intervals (CIs) for the ratios of geometric least-squares means (gLSMs) were within the predefined 80-125% equivalence margin. Secondary PK parameters, immunogenicity, and safety outcomes were also assessed. RESULTS: Of 314 participants randomized (155 CT-P47 AI; 159 CT-P47 PFS), 310 received the study drug (153 CT-P47 AI; 157 CT-P47 PFS). Primary and secondary PK results, immunogenicity and safety were similar between groups. Ninety percent CIs for the ratio of gLSMs were within the predefined equivalence margin for AUC0-inf (85.87-102.94) and Cmax (82.98-98.16). CONCLUSIONS: PK equivalence between CT-P47 AI and CT-P47 PFS was demonstrated in healthy Asian adults, with comparable immunogenicity and safety between the two devices. TRIAL REGISTRATION: ClinicalTrials.gov: NCT05617183.

Tocilizumab is a biologic medicine used to treat inflammatory diseases, such as rheumatoid arthritis. A biosimilar is a drug that is an almost identical copy of an approved original ('reference') biologic medicine; it has identical efficacy and safety to the original medicine but is typically less expensive. CT­P47 is in development as a possible tocilizumab biosimilar.Some patients prefer injections using an auto-injector (AI) rather than a pre-filled syringe (PFS), for reasons including ease of use and convenience. With an AI, medicine is delivered automatically by firmly pressing the device against the skin, whereas, with a PFS, a needle is inserted into the skin and medicine delivered by depressing the plunger. The injection of CT­P47 using a PFS has shown comparable pharmacokinetics (i.e., the uptake, metabolism and excretion of the drug by the body) and safety to tocilizumab. Therefore, if the pharmacokinetics and safety of CT­P47 administered via AI and PFS were shown to be similar, this might expand the choice of administration devices available to patients.In this study, 310 healthy adults received a single injection of CT­P47 via AI or PFS. Blood samples were taken over 43 days to analyze pharmacokinetics. The uptake, metabolism and elimination of CT­P47 by the body was similar when administered by each device, suggesting that CT­P47 can be administered by either AI or PFS.

Cutaneous pharmacokinetics-based bioequivalence: A clinical dermal open flow microperfusion verification study using lidocaine and prilocaine combination topical products.

BACKGROUND: Using accurate, sensitive, reproducible and efficient in vivo cutaneous pharmacokinetics (PK)-based bioequivalence (BE) approaches can promote the development of topical generic drug products. A clinical dermal open flow microperfusion (dOFM) study has previously demonstrated the BE of topical drug products containing a hydrophilic drug. However, the utility of dOFM to evaluate the topical BE of drug products containing moderately lipophilic drugs, more representative of most topical drugs, has not yet been established. OBJECTIVE: To evaluate the ability of a clinical dOFM study to assess BE of topical products containing two moderately lipophilic drugs that have only minor differences in chemical and physical properties. METHODS: The study included 20 healthy subjects. Four application sites on each thigh were treated with fixed dose lidocaine/prilocaine combination products, and dermal drug concentrations were monitored with two dOFM probes per application site for 12 h. A reference cream was compared to itself and to an approved generic cream (both serving as positive controls for BE), and to a gel (negative control). BE was established based on AUC0to12h and Cmax using the scaled-average-BE approach. Systemic exposure of both drugs was assessed throughout the study. RESULTS: BE was successfully demonstrated for the positive controls, and not for the negative control, for both drugs. The systemic exposure of both drugs was negligible. CONCLUSIONS: dOFM accurately demonstrated BE between bioequivalent topical creams, sensitively discriminated between different formulations and differentiated the cutaneous PK of both study drugs, even though they differ only slightly in chemical and physical properties. These results support the utility of dOFM as a cutaneous PK-based BE approach for topical lipophilic drugs, including lidocaine and prilocaine.

Evaluation of Pharmacokinetics of a BCS Class III Drug with Two Different Study Designs: Tenofovir Alafenamide Monofumarate Film-coated Tablet.

Tenofovir alafenamide (TAF) is a BCS Class III compound and an oral pro-drug of Tenofovir (TFV) with limited oral bioavailability. The bioavailability of the oral intake increases with food as a result of the low stability of the active substance in the stomach. The reference drug is "Vemlidy® 25 mg Film Tablet", which contains 25 mg of TAF in "hemifumarate" form, is under patent protection until 15.08.2032 by Gilead, and so the "monofumarate" form was used in the present study. At first, a pilot study was conducted involving 12 subjects under fed conditions. The results of the pilot study revealed the test and reference products were not bioequivalent, as a result of insufficient statistical power and high inter-subject variability. Secondly, a physiologically based pharmacokinetic (PBPK) simulation was performed based on the pilot study results and literature data. Finally, the power of the design was increased and the pivotal study design was optimized into a four-period, full-replicated, cross-over study with 34 subjects under fed conditions and it was concluded that the test and reference products were bioequivalent. In conclusion, the present study proved the importance of a correct study design with higher statistical power for a BCS Class III compound with high variability, to present the pharmacokinetics.