Search Results (45)

Background: The use of optical microscopic techniques has gained increasing attention in recent years for studying the bioavailability (BA) and bioequivalence (BE) of topical drugs. Stimulated Raman scattering (SRS), one type of optical imaging technique, probes chemical-specific information and has excellent spatiotemporal resolution. It uses intrinsic molecular vibrational signatures, and therefore, labeling samples or other treatments is unnecessary to track a molecule. Because of its unique advantages, studies have used SRS for BA evaluations and, more recently, for BE evaluations. In BE evaluation, low data variance within a treatment group is important to ensure sensitivity and specificity in comparing treatment groups. Methods: When measuring forward-direction SRS signals transmitted through skin, the signal intensity is susceptible to variance due to several factors, such as the microscope system’s performance, the different optical features of topical drug products, and the heterogeneity of skin in transmitting light. This work closely investigated the effects of these factors on an SRS signal and developed solutions to reduce their effects on the data variance. Specifically, we constructed a method using a dual-modality detector built in-house, which simultaneously measured both the SRS signal and total light transmission synchronized in time and co-registered in space. Results: We developed equations to normalize SRS signals using the transmission intensity, and the results demonstrated a clear improvement in the SRS signal via a reduction in the signal variance (up to a 9.46% CV value decrease) that is otherwise caused by various factors associated with the use of topical drugs and the composition of the skin. We carried out an exploratory BE study using tretinoin-containing topical products and observed improvements in BE assessment with the developed method (could achieve a reduction of 0.11 in the CI value). Conclusions: This work has led to a better understanding of the factors that affect SRS imaging and has provided an effective method to compensate for these factors in BE assessments. This is a critical initial effort for better practical implementation of SRS in cutaneous pharmacokinetics (cPKs) studies of topical drugs. Full article

Sitagliptin is an orally bioavailable selective DPP4 inhibitor that reduces blood glucose levels without significant increases in hypoglycemia. The aim of this study was to design and validate an innovative, rapid, and highly sensitive LC–MS/MS assay for the precise measurement of sitagliptin concentrations in human plasma. This analytical method, utilizing sitagliptin-d4 as the internal standard, is performed using only 100 μL of plasma and a liquid–liquid extraction procedure based on methyl tert-butyl ether (MTBE). Chromatographic separation is expertly achieved with a Kinetex^® C18 column under isocratic elution, employing a perfect 1:1 blend of 5 mM ammonium acetate (with 0.04% formic acid) and acetonitrile, and maintaining an efficient flow rate of 0.2 mL/min. Detection occurs in positive ionization mode through multiple reaction monitoring, precisely targeting transitions of m/z 408.2 → 193.0 for sitagliptin and 412.2 → 239.1 for the IS. The total runtime of this assay is under 2 min. Comprehensive validation in line with MFDS and FDA criteria demonstrates outstanding linearity (5–1000 ng/mL, r² > 0.998), alongside impressive levels of accuracy, precision, recovery and sample stability. Due to its minimal sample requirement and high-throughput capability, the validated approach is highly appropriate for pharmacokinetic and bioequivalence assessments involving sitagliptin. Full article

This study introduces artificial intelligence as a powerful tool to transform bioequivalence (BE) trials. We apply advanced generative models, specifically Wasserstein Generative Adversarial Networks (WGANs), to create virtual subjects and reduce the need for real human participants in generic drug assessment. Although BE studies typically involve small sample sizes (usually 24 subjects), which may limit the use of AI-generated populations, our findings show that these models can successfully overcome this challenge. To show the utility of generative AI algorithms in BE testing, this study applied Monte Carlo simulations of 2 × 2 crossover BE trials, combined with WGANs. After training of the WGAN model, several scenarios were explored, including sample size, the proportion of subjects used for the synthesis of virtual subjects, and variabilities. The performance of the AI-synthesized populations was tested in two ways: (a) first, by assessing the similarity of the performance with the actual population, and (b) second, by evaluating the statistical power achieved, which aimed to be as high as that of the entire original population. The results demonstrated that WGANs could generate virtual populations with BE acceptance percentages and similarity levels that matched or exceeded those of the original population. This approach proved effective across various scenarios, enhancing BE study sample sizes, reducing costs, and accelerating trial durations. This study highlights the potential of WGANs to improve data augmentation and optimize subject recruitment in BE studies. Full article

Current developments in bioequivalent technology have led to the creation of excellent models that mimic the structure and function of human organs. These models are based on the original tissues and organs of the human body, but they lack the complex interaction with the extensive network of vasculature, and this is a major challenge for these models. A functional vasculature is essential for oxygen, nutrient, and waste exchange. It is also responsible for inductive biochemical exchange, and provides a structural pattern for organ growth. In vitro systems, containing no perfusable vessels, suffer from the quick formation of a necrotic core of organoids, and further development does not occur due to increased metabolic demands. Another key limitation of 3D-based techniques is the absence of accurate architectural structures and large-scale tissue sizes. Recently, new 3D bioprinting methods have been developed for organoids and spheroids as living building blocks. These methods aim to address some of the challenges associated with 3D technologies. In this review, we discuss recent strategies for vascularization via organoids and spheroids, which are used as structural units in bioprinting to recreate natural organs and tissues with ever-increasing accuracy in structure and function. Full article

Transmucosal drug products, such as aerosols, films, semisolids, suppositories, and tablets, have been developed for the treatment of various human diseases and conditions. Transmucosal drug absorption is highly influenced by the biological structures of the mucosa and the physiological environment specific to the administration route (e.g., nasal, rectal, and vaginal). Over the last few decades, in vitro permeation testing (IVPT) using animal tissues or in vitro cell cultures have been utilized as a cost-effective and efficient tool for evaluating drug release and permeation behavior, assisting in formulation development and quality control of transmucosal drug delivery systems. This review summarizes the key mucosal permeation barriers associated with representative transmucosal administration routes, as well as considerations for IVPT method development. It highlights various IVPT methods, including vertical diffusion cell, flow-through diffusion cell, Ussing chamber, and transwell systems. Additionally, future perspectives are discussed, such as the use of optical methods to study in vitro drug permeation and the development of in vitro–in vivo correlation (IVIVC) for transmucosal drug development. The potential of IVPT as part of in vitro bioequivalence assessment strategies for locally acting transmucosal drug products is also highlighted. Full article

Objectives: Tacrolimus, a Biopharmaceutics Classification System (BCS) class II drug, is widely used for transplant patients to prevent graft rejection. To enhance its bioavailability, amorphous solid dispersion (ASD) formulations were developed and evaluated. The release properties of several ASD-based tacrolimus formulations were studied using an in-house USP IV dissolution method. Methods: The pharmacokinetics of a promising test product were compared with the commercially available Advagraf^® in a pilot clinical bioequivalence study with 12 healthy subjects. A previously published PBPK model for tacrolimus was validated using in vivo data and then applied to predict the human pharmacokinetics of several ASD-based tacrolimus formulations. Results: This study compares the pharmacokinetic (PK) parameters—AUC, Cmax, and Tmax—of Advagraf^® and a test formulation using two methodologies: one incorporating the dissolution profile directly into the PBPK model and the other utilizing the DLM approach. The results show that both methods provided accurate predictions for Cmax and Tmax, with the dissolution profile approach underestimating AUC slightly, while the DLM method predicted AUC adequately. Sensitivity analysis refining the DLM scalars in the Ileum and Colon led to optimized predictions of PK parameters. Furthermore, this study explores the use of PBPK modeling to predict in vivo behavior for additional tacrolimus formulations, highlighting the influence of formulation composition, such as the inclusion of Eudragit-S100, on dissolution profiles and bioavailability. Conclusions: This study evaluates formulations with different compositions and manufacturing characteristics; key factors that could influence their performance in the body were identified. These insights—spanning qualitative, quantitative, and manufacturing aspects—can greatly simplify the development of generic drugs, offering strong evidence of the critical role that physiologically based pharmacokinetic (PBPK) modeling can play in the early phases of generic drug development, especially in designing and assessing biopredictive dissolution methods. Full article

A fast and sample cleanup approach for fluoxetine in human plasma was developed using protein precipitation coupled with LC–MS-MS. Samples were treated with methanol prior to LC–MS-MS analysis. Chromatographic separation was performed on a reverse phase column with an isocratic mobile phase of methanol and 10 mM ammonium formate pH acidified with formic acid (80:20, v/v) at a flow rate of 0.2 mL/min. The run time was 4 min. Mass parameters were optimized to monitor transitions at m/z [M + H]⁺ 310 > > 148 for fluoxetine and m/z [M + H]⁺ 315.1 > > 153 for fluoxetine-d5 as an internal standard. The lower limit of quantification and the dynamic range were 0.25 and 0.25–50 ng/mL, respectively. Linearity was good for intra-day and inter-day validations (R² = 0.999). The matrix effect was acceptable with CV% < 15 and accuracy% < 15. The hemolytic effect was negligible. Fluoxetine was stable in human plasma for 48 h at room temperature (25 °C), for 12 months frozen at −25 °C, for 48 h in an auto-sampler at 6 °C, and for three freeze/thaw cycles. The validated method was applied in a pharmacokinetic study to determine the concentration of fluoxetine in plasma samples. The study provides a fast and simple bioanalytical method for routine analysis and may be particularly useful for bioequivalence studies. The method was successfully applied to a pharmacokinetic study of fixed-dose fluoxetine in nine healthy volunteers. Full article

Tadalafil (TD) has poor water solubility but is well absorbed without affecting food intake when administered orally. Owing to patient adherence and therapeutic characteristics, a TD-loaded orodispersible film (TDF) is preferable. However, the mechanistic role of dietary status on the clinical pharmacokinetic analysis of TDF in human volunteers should be investigated because the gastrointestinal environment varies periodically according to meal intervals, although commercial 20 mg TD-loaded tablets (TD-TAB, Cialis^® tablet) may be taken with or without food. TDF was prepared by dispersing TD in an aqueous solution and polyethylene glycol 400 to ensure good dispersibility of the TD particles. In the fasting state, each T/R of Cmax and AUC between TD-TAB and TDF showed bioequivalence with 0.936–1.105 and 1.012–1.153, respectively, and dissolution rates in 1000 mL water containing 0.5% SLS were equivalent. In contrast, TDF was not bioequivalent to TD-TAB under the fed conditions by the C_max T/R of 0.610–0.798. The increased dissolution rate of TDF via the micronization of drug particles and the reduced viscosity of the second meal content did not significantly affect the bioequivalence. Interestingly, an increase in second meal intake time from 4 h to 6 h resulted in the bioequivalence by the Cmax T/R of 0.851–0.998 of TD-TAB and TDF. The predictive diffusion direction model for physical digestion of TD-TAB and TDF in the stomach after the first and second meal intake was successfully simulated using computational fluid dynamics modeling, accounting for the delayed drug diffusion of TDF caused by prolonged digestion of stomach contents under postprandial conditions. Full article

Cefaclor is a substrate of human-peptide-transporter-1 (PEPT1), and the impact of inter-individual pharmacokinetic variation due to genetic polymorphisms of solute-carrier-family-15-member-1 (SLC15A1) has been a topic of great debate. The main objective of this study was to analyze and interpret cefaclor pharmacokinetic variations according to genetic polymorphisms in SLC15A1 exons 5 and 16. The previous cefaclor bioequivalence results were integrated with additional SLC15A1 exons 5 and 16 genotyping results. An analysis of the structure-based functional impact of SLC15A1 exons 5 and 16 genetic polymorphisms was recently performed using a PEPT1 molecular modeling approach. In cefaclor pharmacokinetic analysis results according to SLC15A1 exons 5 and 16 genetic polymorphisms, no significant differences were identified between genotype groups. Furthermore, in the population pharmacokinetic modeling, genetic polymorphisms in SLC15A1 exons 5 and 16 were not established as effective covariates. PEPT1 molecular modeling results also confirmed that SLC15A1 exons 5 and 16 genetic polymorphisms did not have a significant effect on substrate interaction with cefaclor and did not have a major effect in terms of structural stability. This was determined by comprehensively considering the insignificant change in energy values related to cefaclor docking due to point mutations in SLC15A1 exons 5 and 16, the structural change in conformations confirmed to be less than 0.05 Å, and the relative stabilization of molecular dynamic simulation energy values. As a result, molecular structure-based analysis recently suggested that SLC15A1 exons 5 and 16 genetic polymorphisms of PEPT1 were limited to being the main focus in interpreting the pharmacokinetic diversity of cefaclor. Full article

The bioequivalence (BE) of highly variable drugs is a complex issue in the pharmaceutical industry. The impact of this variability can significantly affect the required sample size and statistical power. In order to address this issue, the EMA and FDA propose the utilization of scaled limits. This study suggests the use of generative artificial intelligence (AI) algorithms, particularly variational autoencoders (VAEs), to virtually increase sample size and therefore reduce the need for actual human subjects in the BE studies of highly variable drugs. The primary aim of this study was to show the capability of using VAEs with constant acceptance limits (80–125%) and small sample sizes to achieve high statistical power. Monte Carlo simulations, incorporating two levels of stochasticity (between-subject and within-subject), were used to synthesize the virtual population. Various scenarios focusing on high variabilities were simulated. The performance of the VAE-generated datasets was compared to the official approaches imposed by the FDA and EMA, using either the constant 80–125% limits or scaled BE limits. To demonstrate the ability of AI generative algorithms to create virtual populations, no scaling was applied to the VAE-generated datasets, only to the actual data of the comparators. Across all scenarios, the VAE-generated datasets demonstrated superior performance compared to scaled or unscaled BE approaches, even with less than half of the typically required sample size. Overall, this study proposes the use of VAEs as a method to reduce the necessity of recruiting large numbers of subjects in BE studies. Full article

Sample size is a key factor in bioequivalence and clinical trials. An appropriately large sample is necessary to gain valuable insights into a designated population. However, large sample sizes lead to increased human exposure, costs, and a longer time for completion. In a previous study, we introduced the idea of using variational autoencoders (VAEs), a type of artificial neural network, to synthetically create in clinical studies. In this work, we further elaborate on this idea and expand it in the field of bioequivalence (BE) studies. A computational methodology was developed, combining Monte Carlo simulations of 2 × 2 crossover BE trials with deep learning algorithms, specifically VAEs. Various scenarios, including variability levels, the actual sample size, the VAE-generated sample size, and the difference in performance between the two pharmaceutical products under comparison, were explored. All simulations showed that incorporating AI generative algorithms for creating virtual populations in BE trials has many advantages, as less actual human data can be used to achieve similar, and even better, results. Overall, this work shows how the application of generative AI algorithms, like VAEs, in clinical/bioequivalence studies can be a modern tool to significantly reduce human exposure, costs, and trial completion time. Full article

Biphasic in vitro dissolution testing is an attractive approach to reflect on the interplay between drug dissolution and absorption for predicting the bioperformance of drug products. The purpose of this study was to investigate the in vivo relevance of a biphasic dissolution test for the immediate release (IR) formulations of a Biopharmaceutics Classification System (BCS) Class II drug, lamotrigine (LTG). The biphasic dissolution test was performed using USP apparatus II with the dual paddle modification. A level A in vitro-in vivo correlation (IVIVC) was constructed between the in vitro partition into the octanol and absorption data of the reference product. A good relation between in vitro data and absorption was obtained (r² = 0.881). The one-compartment open model was introduced to predict the human plasma profiles of the test product. The generic product was found to be bioequivalent to the original product in terms of 80–125% bioequivalence (BE) criteria (85.9–107% for the area under the plasma concentration curve (AUC) and 82.7–97.6% for the peak plasma concentration (C_max) with a 90% confidence interval (CI)). Overall, it was revealed that the biphasic dissolution test offers a promising ability to estimate the in vivo performance of IR formulations of LTG, providing considerable time and cost savings in the development of generic drug products. Full article

One of the potential essential factors that restricts generic industry from applying the Biopharmaceutics Classification System (BCS) Class III biowaiver is adherence to the stringent formulation criteria for formulation qualitative (Q1) sameness and quantitative (Q2) similarity. The present study has investigated formulations and excipients from 16 putative BCS Class III drug substances in a total of 19 drug products via 133 approved abbreviated new drug applications (ANDAs) containing in vivo bioequivalence (BE) studies in human subjects during the time period from 2006 to 2022. We included the BCS Class III drugs in this study by referring to published literature, the World Health Organization (WHO) BCS Class I-IV list, FDA internal assessments, and physicochemical properties (high solubility and low permeability) of specific drug substances. Based upon all 133 approved generic formulations in this study, the highest amount of each different compendial excipient with a total of 40 is defined as its corresponding typical amount that has not shown any potential impact on in vivo drug absorption. In the present study, although only 30.08% of the investigated generic formulations met Q1 the same/Q2 similar formulation criteria for the BCS Class III biowaiver, and while approximately 69.92% failed to meet those criteria with non-Q1/Q2 similar formulations, all test/reference ratios (T/R) and 90% confidence intervals for all instrumental PK parameters (AUC_0-t, AUC_0-inf, and Cmax) met the bioequivalence (BE) criteria (80–125%). The results of formulation assessment suggest that the commonly used excipients without atypical amounts did not impact absorption of 16 putative BCS Class III drug substances. The rate and extent of absorption of drugs appears to be more dependent upon the biopharmaceutic and physiochemical properties of BCS Class III drug substance and less, or not dependent upon their formulations, excipients, and the excipients class. Our findings may lead to a more flexible formulation design space regarding the stringent BCS Class III formulation criteria. Full article

Cephalexin is a first-generation β-lactam antibiotic used in adults and pediatrics to treat various streptococcal and staphylococcal infections. This review aims to summarize and evaluate all the pharmacokinetic (PK) data on cephalexin by screening out all pertinent studies in human beings following the per oral (PO) route. By employing different online search engines such as Google Scholar, PubMed, Cochrane Central, and Science Direct, 23 studies were retrieved, among which nine were in healthy subjects, five in diseased ones, and the remaining were drug–drug, drug–food, and bioequivalence-related. These studies were included only based on the presence of plasma concentration-time profiles or PK parameters, i.e., maximum plasma concentration (C_max), half-life (t_1/2) area under the curve from time 0-infinity (AUC_0–∞), and clearance (CL/F). A dose-proportional increase in AUC_0–∞ and C_max can be portrayed in different studies conducted in the healthy population. In comparison to cefaclor, C_max was recorded to be 0.5 folds higher for cephalexin in the case of renal impairment. An increase in AUC_0–∞ was seen in cephalexin on administration with probenecid, i.e., 117 µg.h/mL vs. 68.1 µg.h/mL. Moreover, drug–drug interactions with omeprazole, ranitidine, zinc sulfate, and drug–food interactions for cephalexin and other cephalosporins have also been depicted in different studies with significant changes in all PK parameters. This current review has reported all accessible studies containing PK variables in healthy and diseased populations (renal, dental, and osteoarticular infections, continuous ambulatory peritoneal dialysis) that may be favorable for health practitioners in optimizing doses among the latter. Full article

Pharmacometric analysis is often used to quantify the differences and similarities between formulation prototypes. In the regulatory framework, it plays a significant role in the evaluation of bioequivalence. While non-compartmental analysis provides an unbiased data evaluation, mechanistic compartmental models such as the physiologically-based nanocarrier biopharmaceutics model promise improved sensitivity and resolution for the underlying causes of inequivalence. In the present investigation, both techniques were applied to two nanomaterial-based formulations for intravenous injection, namely, albumin-stabilized rifabutin nanoparticles and rifabutin-loaded PLGA nanoparticles. The antibiotic rifabutin holds great potential for the treatment of severe and acute infections of patients co-infected with human immunodeficiency virus and tuberculosis. The formulations differ significantly in their formulation and material attributes, resulting in an altered biodistribution pattern as confirmed in a biodistribution study in rats. The albumin-stabilized delivery system further undergoes a dose-dependent change in particle size which leads to a small yet significant change in the in vivo performance. A second analysis was conducted comparing the dose fraction-scaled pharmacokinetic profiles of three dose levels of albumin-stabilized rifabutin nanoparticles. The dose strength affects both the nanomaterial-related absorption and biodistribution of the carrier as well as the drug-related distribution and elimination parameters, increasing the background noise and difficulty of detecting inequivalence. Depending on the pharmacokinetic parameter (e.g., AUC, C_max, Cl_obs), the relative (percentage) difference from the average observed using non-compartmental modeling ranged from 85% to 5.2%. A change in the formulation type (PLGA nanoparticles vs. albumin-stabilized rifabutin nanoparticles) resulted in a similar level of inequivalence as compared to a change in the dose strength. A mechanistic compartmental analysis using the physiologically-based nanocarrier biopharmaceutics model led to an average difference of 152.46% between the two formulation prototypes. Albumin-stabilized rifabutin nanoparticles tested at different dose levels led to a 128.30% difference, potentially due to changes in particle size. A comparison of different dose strengths of PLGA nanoparticles, on average, led to a 3.87% difference. This study impressively illustrates the superior sensitivity of mechanistic compartmental analysis when dealing with nanomedicines. Full article