An open label bioequivalence study of oral saquinavir (RO 31-8959) using a stable isotope formulation of saquinavir as an “in vivo” internal standard

SummaryA prospective, open-label multicenter investigation has been conducted to compare pharmacokinetic parameters of recombinant DNA-derived FVIII (rFVIII) and plasma-derived FVIII concentrate (pdFVIII) and to assess safety and efficacy of long-term home-treat- ment with rFVIII for subjects with hemophilia A. Following comparative in vivo pharmacokinetic studies, 69 patients with severe (n = 67) or moderate (n = 2) hemophilia A commenced a program of home treatment using rFVIII exclusively for prophylaxis and treatment of all bleeding episodes for a period of 1.0 to 5.7 years (median 3.7 years). The mean in vivo half-lives of rFVIII and pdFVIII were both 14.7 h. In vivo incremental recoveries at baseline were 2.40%/IU/kg and 2.47%/IU/kg, respectively (p = 0.59). The response to home treatment with rFVIII was categorized as good or excellent in 3,195 (91.2%) of 3,481 evaluated bleeding episodes. Thirteen patients received rFVIII for prophylaxis for twenty-four surgical procedures. In all cases, hemostasis was excellent. Adverse reactions were observed in only 13 of 13,591 (0.096%) infusions of rFVIII; none was serious. No patient developed an inhibitor to r FVIII.

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Has the Time Come to Employ Population and Individual Bioequivalence for the Evaluation of Generics?

Current Drug Metabolism ◽

10.2174/1389200221666200401105119 ◽

2020 ◽

Vol 21 (2) ◽

pp. 112-125

Author(s):

Francis Micheal ◽

Mohanlal Sayana ◽

Rajendra Prasad ◽

Balamurali Musuvathi Motilal

Keyword(s):

Therapeutic Index ◽

Bioequivalence Study ◽

Open Label ◽

Statistical Parameters ◽

Population Mean ◽

Average Bioequivalence ◽

Individual Bioequivalence ◽

Population Bioequivalence ◽

Enteric Coated ◽

Bioequivalence Assessment

Background: Bioequivalence studies are a vital part of drug development. The average bioequivalence approach is the standard method of assessment to conclude whether the generic product is bioequivalent to the innovator product. Of late, debates are on whether the average bioequivalence approach adequately addresses drug interchangeability as it considers only population mean for the evaluation especially when highly variable drug products and narrow therapeutic index drugs are dealt with. Hence, the alternative approaches like population bioequivalence and individual bioequivalence assessment approaches emerge as they consider inter/intra-subject variance and subject- by-formulation variance along with population mean. Objectives: The objective of the study was to apply different bioequivalence assessment approaches in a replicate bioequivalence study to evaluate the drug interchangeability. Methods: This was an open-label, single-dose, randomized, balanced, two-treatment, three-period, three-sequence, partial replicate crossover bioequivalence study of omeprazole enteric-coated tablet 20 mg conducted on 48 normal healthy subjects under fed conditions. The plasma concentration of omeprazole was analyzed by a validated bioanalytical method to determine the pharmacokinetic and statistical parameters to assess average bioequivalence, population bioequivalence, and individual bioequivalence. Results: In this study, test formulation was shown to be bio-inequivalent to the reference formulation by average bioequivalence, population bioequivalence, and individual bioequivalence approaches. Conclusion: The outcome of the evaluation clearly states that the bioequivalence outcome of all these approaches are the same. Obviously, it does not mean that these three approaches provide the same outcome though the consideration of variances varies. Certainly, population bioequivalence and individual bioequivalence approach will be more accurate for the assessment of drug interchangeability.

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An In Vivo Rat α-D-glucose Stable Isotope Homeostasis Drug Discovery Screen: A Targeted Metabolomics Approach

Current Topics in Medicinal Chemistry ◽

10.2174/1568026617666170707130401 ◽

2017 ◽

Vol 17 (24) ◽

Author(s):

Gary W. Caldwell ◽

Wensheng Lang

Keyword(s):

Drug Discovery ◽

Stable Isotope ◽

Targeted Metabolomics

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Physiological impact of in vivo stable isotope tracing on cancer metabolism

Molecular Metabolism ◽

10.1016/j.molmet.2021.101294 ◽

2021 ◽

pp. 101294

Author(s):

Manuel Grima-Reyes ◽

Adriana Martinez-Turtos ◽

Ifat Abramovich ◽

Eyal Gottlieb ◽

Johanna Chiche ◽

...

Keyword(s):

Stable Isotope ◽

Cancer Metabolism ◽

Isotope Tracing ◽

Physiological Impact

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Comprehensive assessment of post-prandial protein handling by the application of intrinsically labelled protein in vivo in human subjects

Proceedings of The Nutrition Society ◽

10.1017/s0029665120008034 ◽

2021 ◽

pp. 1-9

Author(s):

Jorn Trommelen ◽

Andrew M. Holwerda ◽

Philippe J. M. Pinckaers ◽

Luc J. C. van Loon

Keyword(s):

Protein Synthesis ◽

Amino Acid ◽

Stable Isotope ◽

Dietary Protein ◽

Protein Metabolism ◽

Muscle Protein ◽

Human Subjects ◽

Whole Body ◽

Body Protein

All human tissues are in a constant state of remodelling, regulated by the balance between tissue protein synthesis and breakdown rates. It has been well-established that protein ingestion stimulates skeletal muscle and whole-body protein synthesis. Stable isotope-labelled amino acid methodologies are commonly applied to assess the various aspects of protein metabolism in vivo in human subjects. However, to achieve a more comprehensive assessment of post-prandial protein handling in vivo in human subjects, intravenous stable isotope-labelled amino acid infusions can be combined with the ingestion of intrinsically labelled protein and the collection of blood and muscle tissue samples. The combined application of ingesting intrinsically labelled protein with continuous intravenous stable isotope-labelled amino acid infusion allows the simultaneous assessment of protein digestion and amino acid absorption kinetics (e.g. release of dietary protein-derived amino acids into the circulation), whole-body protein metabolism (whole-body protein synthesis, breakdown and oxidation rates and net protein balance) and skeletal muscle metabolism (muscle protein fractional synthesis rates and dietary protein-derived amino acid incorporation into muscle protein). The purpose of this review is to provide an overview of the various aspects of post-prandial protein handling and metabolism with a focus on insights obtained from studies that have applied intrinsically labelled protein under a variety of conditions in different populations.

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Linking a rapid throughput plate-assay with high-sensitivity stable-isotope label LCMS quantification permits the identification and characterisation of low β-L-ODAP grass pea lines

BMC Plant Biology ◽

10.1186/s12870-019-2091-5 ◽

2019 ◽

Vol 19 (1) ◽

Cited By ~ 1

Author(s):

Peter M. F. Emmrich ◽

Martin Rejzek ◽

Lionel Hill ◽

Paul Brett ◽

Anne Edwards ◽

...

Keyword(s):

Stable Isotope ◽

Internal Standard ◽

High Sensitivity ◽

Spectrophotometric Assay ◽

Rapid Screening ◽

Grass Pea ◽

Stable Isotope Label ◽

Tissue Samples ◽

Plate Assay ◽

Accurate Quantification

Abstract Background Grass pea (Lathyrus sativus) is an underutilised crop with high tolerance to drought and flooding stress and potential for maintaining food and nutritional security in the face of climate change. The presence of the neurotoxin β-L-oxalyl-2,3-diaminopropionic acid (β-L-ODAP) in tissues of the plant has limited its adoption as a staple crop. To assist in the detection of material with very low neurotoxin toxin levels, we have developed two novel methods to assay ODAP. The first, a version of a widely used spectrophotometric assay, modified for increased throughput, permits rapid screening of large populations of germplasm for low toxin lines and the second is a novel, mass spectrometric procedure to detect very small quantities of ODAP for research purposes and characterisation of new varieties. Results A plate assay, based on an established spectrophotometric method enabling high-throughput ODAP measurements, is described. In addition, we describe a novel liquid chromatography mass spectrometry (LCMS)-based method for β-L-ODAP-quantification. This method utilises an internal standard (di-13C-labelled β-L-ODAP) allowing accurate quantification of β-L-ODAP in grass pea tissue samples. The synthesis of this standard is also described. The two methods are compared; the spectrophotometric assay lacked sensitivity and detected ODAP-like absorbance in chickpea and pea whereas the LCMS method did not detect any β-L-ODAP in these species. The LCMS method was also used to quantify β-L-ODAP accurately in different tissues of grass pea. Conclusions The plate-based spectrophotometric assay allows quantification of total ODAP in large numbers of samples, but its low sensitivity and inability to differentiate α- and β-L-ODAP limit its usefulness for accurate quantification in low-ODAP samples. Coupled to the use of a stable isotope internal standard with LCMS that allows accurate quantification of β-L-ODAP in grass pea samples with high sensitivity, these methods permit the identification and characterisation of grass pea lines with a very low ODAP content. The LCMS method is offered as a new ‘gold standard’ for β-L-ODAP quantification, especially for the validation of existing and novel low- and/or zero-β-L-ODAP genotypes.

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