title: Update on in vitro cytotoxicity assays for drug development.
abstract: BACKGROUND
  in vitro cytotoxicity testing provides a crucial means of ranking compounds for consideration in drug discovery. The choice of using a particular viability or cytotoxicity assay technology may be influenced by specific research goals.
  
  
  OBJECTIVE
  Although the high-throughput screening (HTS) utility is typically dependent upon sensitivity and scalability, it is also impacted by signal robustness and resiliency to assay interferences. Further consideration should be given to data quality, ease-of-use, reagent stability, and matters of cost-effectiveness.
  
  
  METHODS
  Here we focus on three main classes of assays that are at present the most popular, useful, and practical for HTS drug discovery efforts. These methods measure: i) viability by metabolism reductase activities; ii) viability by bioluminescent ATP assays; or iii) cytotoxicity by enzymes 'released' into culture medium. Multi-parametric technologies are also briefly discussed.
  
  
  CONCLUSIONS
  Each of these methods has its relative merits and detractions; however multi-parametric methods using both viability and cytotoxicity markers may mitigate the inherent shortcomings of single parameter measures.
authors.affiliation: Senior Research Scientist Promega Corporation, Research and Development, 2800 Woods Hollow Road, Madison, Wisconsin, 53711, USA +1 608 247 4330, ext. 1447 ; +1 608 298 4818 ; andrew.niles@promega.com.
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Niles
authors.forename: Richard A
authors.initials: RA
authors.lastname: Moravec
authors.forename: Terry L
authors.initials: TL
authors.lastname: Riss