Pharmacogenetic perspectives in improving pharmacokinetic profiles for efficient bioequivalence trials with highly variable drugs: a review

Conducting bioequivalence trials under traditional crossover study designs without exposing a large number of healthy volunteers to demonstrate two highly variable (%coefficient of variability greater than 30) test/reference (branded) drug products in different formulations to meet the standard 90% confidence interval criteria of relevant pharmacokinetic metrics between 0.80 and 1.25 and to maintain the consumer risk smaller than 5% has been a challenging task. Genetic polymorphisms encoding key drug-metabolizing enzymes can significantly influence absorption, distribution, metabolism and elimination of many highly variable generic drugs after administration. This article briefly reviews the case studies and examples of utilizing pharmacogenetic screening approaches in the recent literature to alleviate the resources and ethical burden of recruiting larger numbers of subjects in bioequivalence trials needed to perform pharmacokinetic studies for formulations of highly variable drug products without widening the bioequivalence acceptance limits.

Bioanalysis and pharmacokinetic studies

Biography: Maria Veneziano is currently a Research Investigator in the DMPK unit at IRBM (Pomezia, Italy), an Italian CRO and biotech company specializing in preclinical drug discovery of small molecules, peptides and antibodies. She studied Biological Science at ‘Federico II’ University of Naples (Italy) and completed her PhD in Medical Biotechnologies at Merck Research Laboratories (MRL) in Rome (Italy) developing bioanalytical methods used to identify and quantify amino acids and acylcarnitines for the diagnosis and follow-up of inborn errors of metabolism. As part of the DMPK team at MRL, she was involved in PK and ADME profiling of small molecule and peptide candidates for drug-discovery programs. Presently, Maria leads a group supporting PK and PK/PD studies for small molecules and peptides. Maria Veneziano speaks to the International Journal of Pharmacokinetics about her experience working on pharmacokinetic studies. She starts by discussing the conventional bioanalytical methods used for the quantitative analysis of small molecules and peptides and she highlights the important role of LC–MS detection and sample preparation in the bioanalysis of pharmacokinetic studies. She also speaks about the role of high-resolution mass spectrometry in the bioanalysis of peptides as an important tool in a drug-discovery program to simultaneously define pharmacokinetic and metabolic profiles of the same drug candidate. She also describes cassette dosing and cassette analysis approaches as strategies to increase sample throughput, highlighting advantages and limits of each of these strategies. Finally, Maria speaks about her idea of ‘simplified PK workflow’ based on the miniaturization and automation of all the steps in a PK study, from in vivo administration to sample analysis.

Intact protein LC–MS for pharmacokinetics

Biography: John Kellie is currently a GlaxoSmithKline (GSK) fellow in the Bioanalysis, Immunogenicity, and Biomarkers group at GSK. John received his B.Sc. in Biochemistry from Indiana University (USA) and his PhD in Chemistry from Northwestern University (USA) studying under Dr Neil Kelleher. He was a post-doctoral scientist at Eli Lilly and Company, where he developed methods for intact protein quantitation of a Parkinson’s Disease biomarker from human brain tissue. At GSK, John utilizes mass spectrometry for development of novel bioanalytical methods for biotherapeutic and protein quantitation from pre-clinical and clinical samples, with a focus on intact protein and large mass quantitation for pharmacokinetics, catabolism, biotransformation and product quality attribute support. John Kellie speaks to the International Journal of Pharmacokinetics about intact protein LC–MS for pharmacokinetic application.

Volumetric absorptive microsampling in pharmacokinetic studies

Biography: Hua Li is currently a Bioanalytical Research Scientist in the NBE Pharmacokinetics Group in the Biotherapeutics Discovery Department at Boehringer Ingelheim (CT, USA). She earned her MA in molecular, cellular and developmental biology from the University of Kansas (KS, USA). While pursuing her master’s degree, she worked as a research assistant on Caenorhabditis elegans genetics. After graduation, she started my career as a research associate and laboratory manager at the Stem Cell Center of Yale University (CT, USA). Her main roles included investigating the essential proteins that play a critical role in the division and differentiation of mouse testes stem cells, as well as administrative responsibilities for a laboratory of around 12 people including graduate students, post-docs and laboratory technician. Since 2008, her career has been focusing on the quantitation of pharmacokinetics and pharmacodynamics study of protein therapeutics. Over the past 12 years, she has witnessed a tremendous expansion of new technologies, devices and theories in the pharmacokinetics/pharmacodynamics field, all of which have helped us better serve the patient community all over the world. Hua Li speaks to the International Journal of Pharmacokinetics about the use of volumetric absorptive microsampling in pharmacokinetic studies and their methodology on the application of Mitra® microsampling for pharmacokinetic bioanalysis of monoclonal antibodies in rats.

Flow cytometry and pharmacokinetic studies

Biography Vellalore Kakkanaiah, PhD serves as the director of the flow cytometry group, which is part of the Biomarker Laboratories at PPD Richmond, VA. His team is focused on the development of flow cytometry methods to support drug development. Recently, his team developed a simple whole blood assay to study the cellular kinetics of CAR-T cells after adoptive cell therapy in multiple myeloma patients. Prior to joining PPD, Dr Kakkanaiah was a senior scientist at SurroMed, Inc. where he developed micro volume laser scanning cytometry assays. He earned a doctorate in immunology from Madurai Kamaraj University in India and then served as a postdoctoral fellow at Virginia Tech. His postdoctoral training involved the first identification of mature CD4-CD8 T cells by flow cytometry from the thymus of an autoimmune mouse model. He was also a fellow of the Arthritis Foundation at the UNC-Chapel Hill. Vellalore N Kakkanaiah speaks to the International Journal of Pharmacokinetics about his experience in developing flow cytometry assays for measuring cellular kinetics in adoptive cell therapies. Flow cytometry is new to bioanalysis and is being used for measuring the cellular kinetics of infused cells from adoptive cell therapy. Here, he discusses the challenges in developing flow cytometry methods for monitoring the infused CAR-T cells.

The impact of micelle size and increased absorption of ubiquinone using a novel delivery system (AquaCelle®)

Aim: The objective of this study was to determine whether the use of a self-emulsifying drug delivery system AquaCelle®, could improve the absorption of CoQ10. Materials & methods: Fifty-seven healthy males and females completed this study with the primary outcome as change in plasma absorption of CoQ10 over a 10-h period. Results: All AquaCelle groups significantly increased CoQ10 concentrations up to three-times that of the standard CoQ10 supplement. Ubiquinone with AquaCelle achieved an equivalent absorption to ubiquinol. Conclusion: The novel delivery system AquaCelle demonstrates superior absorption for the supply of ubiquinone when compared with a standard ubiquinone extract. These results further indicate that ubiquinone with AquaCelle absorbs as effectively as the typically superior absorbing ubiquinol at the same 100 mg dose.

Is the pretransplant C2 an optimum predictor of posttransplant dose for tacrolimus in renal transplantation patients?

Aim: The study evaluated whether a single dose pretransplant 2-h tacrolimus concentration (C2) could predict the post-transplantation trough concentration (C0). Materials & methods: C2 concentration of tacrolimus was measured after single-dose administration (0.1 mg/kg) in 20 patients, 4–7 days prior to renal transplantation. Tacrolimus C0 monitoring was done on post-transplant day 2, 5, 10, 15 and 30. Results: The mean C2 was 21.79 ± 16.83 ng/ml (4.25–69.46) and the mean C0 obtained 48 h after transplant was 10.2 ± 6.27 (1.63–22.07) ng/ml. The Spearman correlation between C2 and C0 was 0.71 (p < 0.01). Conclusion: Pretransplant C2 could explain only 50% of the total variation in the post-transplant dose requirement hence it may not be sole predictor of the post-transplant dose.