需要IC50的计算公式和公式出处
各位前辈，我要发表文章，需要IC50的计算公式和公式出处．和公式的名称．谢谢了．急急急急急急急 注意：楼主需要的是公式和公式出处！不是详细的软件帮助！IC50没有固定的计算公式，大多将剂量和抑制率经一定变换后用非线性回归拟合计算
上述软件是经Logit变换后计算，
我发一个国外用的比较多的中效公式：
Calculate 50% inhibitory concentration (IC50) by the median effect equation and
report both raw and analyzed data as follows:
a. The median effect equation of Chou and coworkers, can be used in one of
the following ways:
1) the exponential form of the equation can be used and a curve fit to the
data points (Fa and drug concentration) using nonlinear regression:
Fraction affected: (Fa) = 1/[1 + (IC50/drug concentration)m]
m = slope of the curve
Fraction affected: (Fa) = % reduction from untreated control x 0.01
Systat (Systat, Inc., Evanston, IL) can solve for IC50 and m
simultaneously using nonlinear regression modeling. After the equation’s
constants (IC50 and m) are determined, a curve of Fa versus drug
concentration can be constructed on a log-linear plot with drug
concentration on the log scale of the x-axis.
2) logarithmic form of the equation can be used and a curve fit to the data
points by linear regression:
Log (Fa/Fu) = m log [drug concentration] - m log [IC50]
Fraction affected: (Fa) = % reduction from untreated control x 0.01
Fraction unaffected: (Fu) = % maximum x 0.01
b. “Dose effect analysis with microcomputers” by Chou and Chou (Biosoft,
Ferguson, MO) calculates the IC50 using linear regression to solve for the
best fit of the data to this logarithmic form of the median effect equation.
When actual values of Fa/Fu and drug concentration are plotted on log-log
scales, the IC50 is the drug concentration that corresponds to y=1. The
Chou and Chou software plots log (Fa/Fu) versus log (drug concentration)
on linear scales, and the IC50 is the y intercept (since log 1 = 0). However,
when using this method, Fu cannot be zero and therefore must be changed
to a consistent arbitrary number if no drug effect is seen at low drug
concentrations.
c. Other software can be used: for nonlinear regression modeling of the
exponential form of the equation, for linear regression modeling of the
logarithmic form of the equation, or for plotting Fa versus drug
concentration (or Fu versus drug concentration) after IC50 has been
determined by solving the median effect equation.
参考：
1：Chou T.-C. 1991. The median-effect principle and the combination index for
quantitation of synergism and antagonism, p. 61–102. In T.-C. Chou and
D. C. Rideout (ed.), Synergism and antagonism in chemotherapy. Academic
Press, San Diego, Calif.
2：Chou TC,Hayball MP.Calcusyn manual:Windows software for dose effect analysis[CP/DK].Cambridge Biosoft(U.K),1996
Chou T. C. The median-effect principle and the combination index for quantitation of synergism
3：Chou TC and Talalay P. Quantitative analysis of dose-effect relationships: the combined effects of multiple drugs or enzyme inhibitors. Adv Enzyme Regul 22:27-55, 1984.
4：Chou TC. The median-effect principle and the combination index for quantitation of synergism and antagonism. Synergism and Antagonism in Chemotherapy, Chou TC and Rideout DC, eds.,Academic Press, San Diego, 1991.
另发一个简便的Reed-Meuench法计算IC50公式：
IC50＝Antilog(B+50%-<50%抑制百分率 >50%抑制百分率/<50%抑制百分率×C)?
A＝log>50%药物浓度 B＝log<50%药物浓度 C＝A-B?
本法的优点是简便，不用计算机也可计算，在病毒学研究中计算TCID50较为多用。 但报告的信息较少，计算结果不如回归法严谨, 由于是用累积法计算，有一定缺陷，误差和重复性较大。
参考：
Reed LJ, Muench H. A simple method of estimating fifty percent endpoints. Am J Hyg, 1938,27(3) :493 - 497.
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