Dr. Fritz Poulsen is a scientific director at ADME & Assay Technology. His laboratory is located within the Diabetes Research Unit of Novo Nordisk in Copenhagen, Denmark. The lab is responsible for new assay technologies, new applications of existing technologies, and for developing new assays for testing samples from especially pharmacodynamic (PD) and pharmacokinetic (PK) studies in the early phases of developing new drugs.
Dr. Poulsen holds an MSc degree in biochemistry from the University of Copenhagen. He earned his PhD degree in molecular immunology from the University of Aarhus. He joined Novo Nordisk in Denmark to help develop immunoassays and immunoassay kits. Starting in 1990, he built and headed the high throughput screening (HTS) unit at Novo Nordisk. In 2003 he became responsible for introducing HTS technology and procedures for testing plasma samples from lab animals, for HT-CYP inhibition testing, and for HT-hERG interaction testing. His current areas of interest include assay technologies, new applications of assay technologies, and application of HTS-like procedures within the drug discovery process.
Fritz’ lab collaborates closely with the Assay Technology department (headed by Annette Rosendal) at Novo Nordisk. This department is responsible for testing samples from PD and PK studies by immunoassays and other biological assays in the early phases of developing new drugs. The assay requirements for PD and PK studies include high sensitivity, broad dynamic range, low sample volume, rapid and high capacity analysis, and low resource consumption.
A major recent achievement for this group was the development of the AlphaLISA® technology in collaboration with PerkinElmer for testing of plasma samples. This technology is also referred to as LOCI in the laboratory’s publications (1).
In a comparison of insulin assays (Figure 1), the AlphaLISA and ELISA assays were based on the same antibodies and were thus directly comparable. The AlphaLISA assay was superior to the ELISA with respect to sensitivity and working range.
EnlargeFigure 1. The insulin AlphaLISA assay displays a greater sensitivity and working range than the corresponding ELISA assay. (Both log:log and linear plots are shown.) For the AlphaLISA assay, the calibrators were in insulin depleted plasma. In ELISA the kit calibrators are used. AlphaLISA and ELISA are based on the same antibodies.
The ability to use lower sample volumes in the AlphaLISA assay is of importance for small animals like mice and rats (Table 1). One caution is that AlphaLISA assays are affected by severe hemolysis. It is thus important to be careful when drawing blood samples and preparing plasma (2).
EnlargeTable 1. Comparison of AlphaLISA and ELISA assay sample volumes and other parameters for three analytes (insulin, Factor VIIa, and glucagon).
The AlphaLISA assays discussed here have been based on monoclonal antibodies, which have shown to be important to achieve the full potential of the AlphaLISA/LOCI technology. Fritz has also been working to develop AlphaLISA sandwich assays based on polyclonal antibodies to achieve shorter assay/antibody development time and to obtain assays with a broader specificity with respect to peptide drug analogues.
Fritz says, "We use AlphaLISA sandwich immunoassays due to their good sensitivity and broad working range for testing animal samples from PK studies where very low and very high analyte samples are used. Light cross-talk issues from high and low samples in neighbouring wells have been observed with many plate types but this has been overcome with the use of [PerkinElmer's] AlphaPlate™ which gives a good reduction in cross talk and no need for cross-talk correction. The AlphaPlates are necessary to realize the full potential of the sandwich AlphaLISA".
Novo Nordisk is the world leading diabetes care company and is also involved in treatment of coagulation and growth disorders. Some of the important products developed by Novo Nordisk are the modern insulins Levemir and NovoRapid/NovoLog for treatment of type I and type II diabetes patients and NovoSeven for treatment of bleedings in haemophilia A and B patients with inhibitors.
Learn more about Alpha Technologies and ELISA Alternative Technologies. To find out more about Novo Nordisk, please visit www.novonordisk.com
References
1. F. Poulsen and K.B. Jensen, J. Biomol. Screening, 2007; 12:240-247
2. S.D. Christensen et al., Laboratory Animals 2009; 43: 65-71