Half Survival Dose

The half-survival dose or CD50 (from the English “Concentration-Dose Response”) is a term used in biology and medicine to describe the dose of a substance that causes a certain effect in half of the subjects. The term can be used to describe a dose of a drug that results in half the survival of patients, or a dose of poison that results in half of the deaths in test subjects.

The half survival dose is an important indicator to determine the effectiveness and safety of a drug or poison. It allows you to determine what dose of a substance can cause a certain effect, without causing unwanted side effects. Also, CD50 can be used to determine the minimum amount of a substance that must be administered to achieve the desired effect.

To determine the half-survival dose, clinical trials are conducted in which subjects receive different doses of the substance. Then, based on the test results, the dose that caused half the survival rate in the subjects is determined. This allows us to determine the effectiveness and safety of a drug or poison for patients.

A half-survival dose (HSD) is a dose of cells (for a virus, bacteria, cancer cell, etc.) at which half of the injected cells die in the body. This definition is directly related to the term lethal dose (LD), which defines the dose of radiation required to kill half the cells in a tissue.

It is clear that the substance can kill tissue cells of different sensitivity to it in different ways. The term "harmless dose" is a relative value: it generally implies that the tissue will remain intact for long periods after treatment.

This definition of “half lethal dose” was developed by the research group of Dmitry Ivanovsky and Mikhail Sumin in scientific collaboration between the Moscow Institute of Applied Biotechnology and Queen Mary Sanin University (UK). In 2013, they became participants in the first large-scale project in Russia to search for cellular concentrations effective in the fight against viruses. According to the authors, the significance of their discovery is not in the creation of a fundamentally new method, but in the development of new approaches based on knowledge of the real antiviral properties and effects of extremely low concentrations of cells, lymphocytes and their components. The results of preclinical studies on this method were transferred to a state medical institution. This method is currently being tested.

In this work, results were obtained indicating the antibacterial property of a lymphocyte, which is defined as the ability to cause the death of pathogenic pathogens (viruses, bacteria, tumor cells), along with a high degree of survival of its own, i.e., healthy human body.

These studies were open and published quite a long time ago, but today scientists are seriously planning to apply this approach to the treatment of most viral infections. Based on previously obtained data, it can be assumed that immunotherapy (treatment with lymphocytes), if necessary, can be aimed at maintaining the body’s immune system; and it can also speed up the recovery process after severe operations and injuries. However, further research is needed to confirm these ideas.