Bioanalysis
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Pharmacokinetic-pharmacodynamic (PK-PD) modeling is an integral part of the preclinical and clinical development of protein drugs. Bioanalytical data from appropriately selected and well-characterized PK and PD biomarker assays can be incorporated into mechanistic PK-PD models and allow a quantitative relationship between protein drug exposure, target modulation, and biochemical, physiological and pathophysiological effects to be established. ⋯ The PK-PD data can provide an important link between magnitude of target modulation and clinical efficacy and safety outcomes, and guide the selection of doses and dosing schedules for clinical trials. In this article, approaches to the selection and development of fit-for-purpose, PK and PD assays for protein drugs are reviewed, and the applications of the assay results in PK-PD models are discussed.
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Dr Janet Woodcock is the Director of the US FDA's Center for Drug Evaluation and Research. Dr Woodcock has held various positions within the FDA's Office of the Commissioner from October 2003 until 1 April 2008, as Deputy Commissioner and Chief Medical Officer, Deputy Commissioner for Operations and Chief Operating Officer and Director of the Critical Path Programs. She oversaw scientific and medical regulatory operations for the FDA. ⋯ She previously served in other positions at the FDA, including Director of the Office of Therapeutics Research and Review and Acting Deputy Director of the Center for Biologics Evaluation and Research. Dr Woodcock received her MD from Northwestern Medical School (IL, USA), and completed further training and held teaching appointments at the Pennsylvania State University (PA, USA) and the University of California in San Francisco (CA, USA). She joined the FDA in 1986.
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Review
Metabolomics for early detection of drug-induced kidney injury: review of the current status.
The identification of biomarkers of drug-induced kidney injury is an area of intensive focus in drug development. Traditional markers of renal function, including blood urea nitrogen and serum creatinine, are not region-specific and only increase significantly after substantial kidney injury. Therefore, more sensitive markers of kidney injury are needed. ⋯ In this review, we describe the current status of the identification of metabolic biomarkers for drug-induced kidney toxicity screening. Many of these markers have been confirmed across multiple studies and can detect nephrotoxicity earlier than the traditional clinical chemistry and histopathology methods. Upon further validation, such markers will offer clear benefits for the pharmaceutical industry and regulatory agencies.
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The terms 'false-positive' and 'false-negative' are widely used in discussions of urine drug test (UDT) results. These terms are inadequate because they are used in different ways by physicians and laboratory professionals and they are too narrow to encompass the larger universe of potentially misleading, inappropriate and unexpected drug test results. This larger universe, while not solely comprised of technically 'true' or 'false' positive or negative test results, presents comparable interpretive challenges with corresponding clinical implications. ⋯ Causes of potentially inappropriate positive UDT results include in vivo metabolic conversions of a drug, exposure to nonillicit sources of a drug and laboratory error. Causes of potentially inappropriate negative UDT results include limited assay specificity, absence of drug in the urine, presence of drug in the urine, but below established assay cutoff, specimen manipulation and laboratory error. Clinical UDT interpretation is a complicated task requiring knowledge of recent prescription, over-the-counter and herbal drug administration, drug metabolism and analytical sensitivities and specificities.