Determination of the LD50 of the drug
Determination of the LD50 of the drug
In toxicology, the median lethal dose, or LD50 (i.e., Lethal Dose, 50%), is a commonly used indicator of the toxicity of a toxic substance or radiation. As defined by the Medical Subject Headings (MeSH), the LD50 is "the dose of a hazardous substance, toxicant, or free radiation that kills half of the total test population". This test was first invented by J.W. Trevan in 1927. The determination of LD50 is used to: (1) measure the toxicity of a drug and evaluate its quality; (2) evaluate the safety of a drug - therapeutic index; and (3) provide pharmacological information that must be provided in the process of declaring a new drug.
Operation method
Experimental determination of the LD50 of drugs
Principle
The LD50 of a drug refers to the single dose of a drug when the mortality rate of the animal is 50% in the acute toxicity test, and the unit is usually mg/kg.For example, when a drug is given in a dose of 400mg, half of the rabbits (weighing about 4kg) can be killed, and the LD50 value is 100mg/kg.The LD50 value usually reflects the magnitude of the acute toxicity of the drug. Acute toxicity and chronic toxicity of drugs belong to the same general toxicology research. In addition, drug toxicology research also includes special toxicology (carcinogenic, teratogenic, mutagenic), drug dependence and allergic reaction experiments. Various genera of animals can be used for the determination of LD50 values of drugs, usually using rodents (rats and mice), sometimes using rabbits and dogs. Barbiturates inhibit the central nervous system, causing sedative, hypnotic, anticonvulsant and anesthetic effects, and when the dose is too high, it can paralyze the vital center and eventually lead to death. This experiment introduces the study of acute toxicity of drugs by learning to determine the LD50 value of sodium pentobarbital.
Materials and Instruments
Mice (Kunming breed) Half male and half female Move 1. Pre-experimentation Caveat 1. In the formal experiments, according to the dose range of 0% and 100% animal deaths in the pre-tests, 5-7 different dose groups are designed according to the equipartition series, and the common ratio is generally 1: 0.8 to 1: 0. 7. 2. There are many methods for calculating the LD50 value, among which the Bliss method, also known as the weighted likelihood unit method or the likelihood unit regular method, is the method currently prescribed for use in the approval of new drugs. It can be calculated by statistical software, such as the statistical software of pharmacodynamics prepared by the Mathematical Pharmacology Committee of the Chinese Pharmacological Society. 3. If the LD50 and ED50 (half effective dose) of a drug are measured at the same time, the therapeutic index can be calculated, i.e., TI = ED50/LD50; in general, the larger the therapeutic index, the safer the drug is. Common Problems Significance: 1, is a measure of the size of drug toxicity indicators, evaluation of the advantages and disadvantages of drugs important parameters 2、Evaluation of drug safety - therapeutic index 3、Declare the pharmacological information that must be provided in the process of new drugs For more product details, please visit Aladdin Scientific website.
Pentobarbital sodium solution Saline solution Picric acid solution
Pentobarbital sodium solution, physiological saline, picric acid solution, measuring cylinder, beaker, syringe, balance.
The mice were randomly divided into 4~5 groups, 3~4 mice in each group. A stock solution of 3% pentobarbital sodium was prepared, which could be further diluted into different concentrations of drug solution. The mice were administered intraperitoneally, and the dose administered to each group was decreasing according to an isometric series. The mortality rate of the animals in each group was recorded. The aim was to find and determine the range of doses that caused 0% versus 100% of the animals to die.
2. Formal experiment
(1) First, separate the male and female mice and weigh them one by one. Female and male mice were sorted according to their body weight from small to large (or from large to small) respectively. Then the mice were divided into 5-7 groups of 10 mice each according to the principle of stratified randomization.
(2) According to the dose range that caused 0% and 100% animal deaths in the preexperiment, 5 to 7 different dose groups were designed in between, so that the dose decreased according to an equipartition series. The time and number of animal deaths were observed and recorded after administration. The observations were made continuously for 7 to 14 days. LD50 values and their 95% confidence intervals were calculated according to the simplified probability method, modified Koch's method, and Bliss method (see bibliography for details).
(3) Count its method (Kou's method):