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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 (2,3) and its combination index theorem (3,4) has achieved its goals. One review article published in 2006 (3) has now been cited 2,115 times in 538 different journals [Google Scholar Citations and Thomson Reuters Web of Science]; and one theoretical article introducing the concept of combination index (CI) and its isobologram algorithm (4) has been cited 5,235 times in 778 journals[]*.

ComboSyn Inc, which always has vision of not-for–profit purpose, had already recovered the software developmental expense and administration cost. On August 1st, 2012, the company announced that as the contribution to the bio-medical research communities, the CompuSyn software has been offered for free download upon registration and adherence to the original terms of usage as indicated in the inner conver of the User's Guide. Researchers who are interested and agree with the terms are welcome to register and download the CompuSyn software along with its User’s Guide free of charge. As of 7/25/2017, there has been 21,526 downloads from 120 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. 8-10 and discussed in Ref. 11.

The website,, will be open to provide general information, a video demo, and illustrated examples of applications, in vitro, in animals, and in clinical trials. This website will be unattended, and will not be open to respond to inquiries.

Best wishes for your scientific endeavor.

ComboSyn, Inc.

*[Citation metrics updated on July 25, 2017:

Ting-Chao Chou - Google Scholar Citations: For total citations:

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 311 times)
  3. Chou TC. Theoretical basis, experimental design, and computerized simulation of synergism and antagonism in drug combination studies. Pharmacol Rev 58:621-681, 2006. (Free web link: [Cited 2,115 times]
  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 5,235 times in 778 different journals).
  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” (A Perspectives Article, cited 1,435 times in 351 journals).
  7. Chou TC. Frequently asked questions in drug combinations and the mass-action law based answers.  Synergy 1: 3-21, 2014 (The inaugural issue of Synergy journal by Elsevier)[]
  8. 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 435 times)
  9. 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 480 times, in 165 journals)
  10. Chou TC. Preclinical versus clinical drug combination studies. Leukemia & Lymphoma 49:2059-80, 2008 (A Review article with real data analysis and computer print-outs).
  11. 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). (DOI: 10.1039/c0ib00130a)