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Announcement from ComboSyn, Inc.

The ComboSyn, Inc., the publisher of CompuSyn software (1), which was set up by Dr. Dorothy Chou in 2005 with purpose of promoting the pharmacodynamic research and simple computerized analytical simulation using the median-effect principle of the mass-action law (2) and its combination index theorem (3,4) has achieved its goals. One review article published in 2006 (3) has now been cited 588 times in 223 different journals [Thomson Reuters ISI Web of Science]; and one theoretical article introducing the concept of combination index (CI) and its isobologram algorithm (4) has been cited 2,994 times in 543 journals, which is about 10% of all biomedical journals in the world []*. The CompuSyn software, since 2005, has been distributed to biomedical scientists in over 34 countries via commercial means. The prior cost for Compusyn software was $399 per license.

ComboSyn Inc, which always has vision of not-for–profit purpose, had already recovered the software developmental expense and administration cost. The company thereby announces that as the contribution to the bio-medical research communities, the CompuSyn software has been available for download without charge beginning August 1st, 2012, upon registration and adherence to the original terms of usage. Researchers who are interested and agree with the terms are welcome to register and download the CompuSyn software with its User’s Guide. As of 01/20/2014, there has been 4,271 downloads from 62 countries.

For the frequently asked questions (FAQ), the pitfalls and the most common errors in applying the theory to biomedical research, please refer to Refs. 5-7. Examples of “real data analysis” and “computer printout” are available in Ref. 3 and its Appendices, as well as Refs. 8-9 and discussed in Ref. 10.

The website,, will be open to provide general information, a video demo, and illustrated examples of applications, in vitro, in animals, and in clinics. This website will be unattended, and will not be open to respond to inquiries.Any consultation requires to be prearranged at

Best wishes for your scientific endeavor.

ComboSyn, Inc.

*[Citation metrics updated on 01/20/2014 from Thomson Reuters Web of Science]

References : (Thomson Reuters Web of Science:

  1. Chou TC and Martin N. CompuSyn for Drug Combinations: PC Software and User’s Guide: A Computer Program for Quantitation of Synergism and Antagonism in Drug Combinations, and the Determination of IC50 and ED50 and LD50 Values, ComboSyn Inc, Paramus, (NJ), 2005.
  2. Chou TC. Derivation and properties of Michaelis-Menten type and Hill type equations for reference ligands. J Theor Biol 59:253-76, 1976. (Cited 156 times)
  3. Chou TC. Theoretical basis, experimental design, and computerized simulation of synergism and antagonism in drug combination studies. Pharmacol Rev 58:621-81, 2006. (Free web link: [Cited 588 times in 223 different journals since 2007, Thomson ISI Web of Science]; (Among the most cited Pharmacological since 2006 in the world)
  4. Chou TC, Talalay P. Quantitative analysis of dose-effect relationships: the combined effects of multiple drugs or enzyme inhibitors. Adv Enzyme Regul 22:27-55, 1984. (Cited 2,994 times in 543 different journals, encompassing nearly all disciplines in biomedical sciences ). (
  5. Chou TC. What is synergy? The Scientist 21:No. 8, p.15, 2007.
  6. Chou TC. Drug combination studies and their synergy quantification using the Chou-Talalay method. Cancer Res 70: 440-446, 2010. “doi: 10.1158/0008-5472.CAN-09-1947” (An invited Perspectives Article, cited 237 times since 2010).
  7. Chou TC. The median-effect principle and the combination index for quantitation of synergism and antagonism. In: Chou TC, Rideout DC, editors. Synergism and Antagonism in Chemotherapy. San Diego: Academic Press; 1991. pp 61-102. (Cited 278 times)
  8. Chou TC, Motzer RJ, Tong Y, Bosl GJ. Computerized quantitation of synergism and antagonism of Taxol, topotecan, and cisplatin against human teratocarcinoma cell growth: a rational approach to clinical protocol design. J Natl Cancer Inst 86:1517-24, 1994. (Cited 339 times, in 121 journals)
  9. Chou TC. Preclinical versus clinical drug combination studies. Leukemia & Lymphoma 49:2059-80, 2008 (An Invited Review article with real data analysis and computer print-outs).
  10. Chou TC. The mass-action law based algorithms for quantitative econo-green bio-research (Perspective Article). Integrative Biol 3: 548-559, 2011 (Featured on the front cover of May 2011 issue) (DOI: 10.1039/c0ib00130a)