Median effective dose (EDfifty）[3]It usually refers to the dose required for the exogenous substance to cause 50% change of a biological effect in the body.Usually less thanLD50It is also a commonly used dose parameter in toxicology.EDfiftyIt is an indicator of drug safety.It means that 50% of the individual effective drug concentration is caused.LD50/ED50, TD50/ED50, TC50/EC50, etc. are collectively referred to asTreatment index, is a safety index of a class of drugs. Generally, the greater the value, the safer it will be.It should be noted that these indicators only reflect the relationship between therapeutic effect and acute toxicity, notChronic toxicity, Allergy.
Median effective dose (EDfifty）The concentration that can cause some effect change of 50% of the tested organism.It usually refers to non death effects.The half effect concentration is related to the test time, usually 24 hours, 48 hours or 96 hours ECfiftyexpress.The experimental organism used to determine the half effect concentration should have obvious reaction characteristics, which is easy to judge, such as slow reaction, reduced movement ability, or other obvious physiological and behavioral changes.The half effective concentration can quickly judge the possible impact of the tested substance on the tested organism, and provide reference for further chronic toxicity research.
computing method
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Usually, the colony diameter method is used to calculate ECfiftyA regression equation is needed.
The inhibition rate of different concentrations of chemicals on the growth of each strain was calculated by the net growth of mycelium.The calculation formula is as follows:
fungusThe measured data take the logarithm of the natural logarithm e of the concentration as the abscissa. By looking up the conversion table of biostatistics probability values, take the probability value corresponding to the inhibition rate as the ordinate, calculate the regression equation and correlation coefficient R of each test concentration, and calculate EC with the probability value corresponding to the inhibition rate of 50%fiftyAnd its 95% confidence interval.
The probability value is the unit of probability, which is divided into 1-40 in total. Its essence is the numerical range obtained by adding and subtracting the standard error from the average of the normal distribution. Each normal equal difference projected on the shoulder line normal equal difference points represents different mortality rates. In this way, the cumulative curve of mortality rates can be calculated by using normal equal difference, and then turned into a straight line.[1]
The upper and lower sequential method is used to determine ED.,Or concentration.This method determines the optimal value through continuous experimental application and correction of the given dose or concentration.The drug ED determined by this method.,It has very accurate guiding significance for clinicians to choose drugs.[2]
