Back to homepage

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).

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. In 2013, the PD Science LLC was established by Ting-Chao (David) Chou, to take care of scientific affairs of ComboSyn Inc. As of 02/08/2022, there has been 45,549 downloads by scientists from 137 countries or territories.

The MAL-PD functional dynamics approach, is an “Top Down” concept with the unified general theory first and applications later. This unique functional dynamics theory/algorithm allows using very few dose-data points to fit the unified general MAL theory, thus to gaining efficiency, cost-effectiveness and automated quantitative simulation. By contrast, the conventional biomedical research usually using the “Bottom Up” approach which start with experiments, findings, empirical data analysis, and then hypothesis or speculation. The conventional concept usually uses many dose-data points to fit empirical curve or empirical formula that have no physical or chemical bearings, and rely heavily on statistical analysis for conclusions. The theoretical “Top Down” and the observational “Bottom Up” approaches are conceptually opposite, but purposely complementary for the general biomedical R&D, with distinct quantitative and digital cost-effective features.

For the frequently asked questions (FAQ) on MAL-PD, Biodynamics (BD) and Bioinformatics (BI) for experimental design and the simulated diagnostic plots/graphics, the pitfalls and the most common errors in applying the theory to biomedical research, please refer to Refs. 5-14. Examples of “real data analysis” and “sample computer printouts” are available in Refs. 3, 9, 15-18, and in the Appendices of Ref. 3. For convenience, some specific examples of design and analysis are also provided in the pulldown menus of this website.

For the updates of search trends and applications of MAL-PD/BD/BI and CI theory, please visit the websites of Google Scholar Citations - Ting-Chao Chou and the Web of Science (Publons), []. It is noted that one review article published by Chou in 2006 (3) has now received 4,552 citations in 1,152 different biomedical journals, and one theoretical article introducing the concept of combination index (CI) and its algorithm by Chou & Talalay in 1984 (4) has received 7,504 citations in 1,446 journals, internationally, encompassing broad spectrum of biomedical sciences, including, drugs, chemicals, biologicals, regardless of units, mode or mechanism of actions. The applications of MAL-PD/BD/BI and CI have been extended to radiation, photochemistry, environmental, marine, and agricultural studies as well as the anti-HIV and anti-SARS-CoV-2 drug evaluations.

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.

PD Science, LLC.

*References and Citation Metrics [Updated February 8, 2022]

For total Citations: Google Scholar Citations – Ting-Chao Chou,

For total Citing Journals: Thomson Reuters Web of Science (Publons),

  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. [Donated to biomedical communities for free download, upon registration, beginning August 1. 2012 via of PD Science LLC]. (Cited 919 times) (45,539 international downloads, as of 02/08/2022)
  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 407 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 4,552 times in 1,152 journals]
  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 7,504 times in 1,446 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 4,187 times in 966 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 939 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 587 times, in 279 journals) DOI: 10.1093/JNCI/86.20.1517
  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).(Cited 254 times) DOI: 10.1080/10428190802353591
  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)
  12. Chou TC. Talalay P. Analysis of combined drug effects: a new look at a very old problem. Trends in Pharmacological Sciences 4, 450-454, 1983 (Cited 651 times) DOI: 10.1016/0165-6147(83)90490-X
  13. Chou TC. The combination index (CI< 1) as the definition of synergism and of synergy claims. Synergy 7, 49-50, 2018 (Cited 44 times).[]
  14. Zhang N, Fu JN, Chou TC, Synergistic combination of microtubule targeting anticancer fludelone with cytoprotective panaxytriol derived from panax ginseng against MX-1 cells in vitro: experimental… Am. J. Cancer Res. 6 (1), 97-104, 2016. (Cited 115 times) (PMID)
  15. Fu JN, Zhang N, Chou JH, Dong HJ, SF Lin SF, Ulrich-Merzenich GS, Chou TC. Drug combination in vivo using combination index method: Taxotere and T607 against colon carcinoma HCT-116 xenograft tumor in nude mice. Synergy 3 (3), 15-30, 2016 (Cited 26 times) []
  16. Baba TW, Liska V, Hofmann-Lehmann R,..Chou TC.. Ruprecht R. Human neutralizing monoclonal antibodies of the IgG1 subtype protect against mucosal simian–human immunodeficiency virus infection. Nature medicine 6 (2), 200-206, 2000. (Cited 1,073 times).[DOI: 10.1038/72309]
  17. Vogt MW, Hartshorn KL, Furman PA, Chou TC, Fyfe JA, Coleman LA, Crumpacker C, Schooley RT, Hirsch MS. Ribavirin antagonizes the effect of azidothymidine on HIV replication. Science 235: 1376-1379, 1987. DOI: 10.1126/SCIENCE.2435003