Included in the formulation
АТХ:V.09.G.X Other radiopharmaceuticals for the diagnosis of diseases of the cardiovascular system
Pharmacodynamics:During incubation in vitro hexavalent radioactive chromium (51Cr: half-life - 27.7 days, type of decay-electron capture, type of radiation: γ-radiation with energy 320 keV, mean number of emissions / decay-0.1) penetrates into erythrocytes and binds to hemoglobin, leukocytes or blood platelets; unbound 51Cr is reduced to a trivalent state in the presence of reducing agents (for example, ascorbic acid), then it is not bound in vivo and can be removed by washing the cells in an isotonic solution. With the introduction of labeled cells, the isotope slowly enters the systemic circulation at a rate of 1% per day. Labeled cells also break down in the reticuloendothelial system (predominantly the spleen), where the radioisotope is slowly released. After intravenous administration of labeled erythrocytes, the trivalent state of 51Cr is maintained until their destruction in the spleen, when 51Cr is released into the plasma. Plasma samples are taken from the patient and placed in a scintillation counter with the determination of the volume of erythrocytes and their lifetime.External registration allows assessing hepatic and splenic decay of erythrocytes. In the diagnosis of gastrointestinal bleeding, feces are taken and dosimetry is performed.
Pharmacokinetics:The life span of normal labeled erythrocytes is 25-35 days (a decrease in comparison with 120 days for normal red blood cells is explained by damage during fencing and blood labeling). Elimination by the kidneys (unrelated trivalent 51Cr), with feces (less than 1% in norm). The concentration of 51Cr in the kidneys reaches 6-8% of the administered amount, the elimination half-life is 2-5 minutes.
Indications:Determination of the lifespan of erythrocytes, leukocytes and platelets in various hematologic diseases; determination of the volume of circulating and deposited red blood cells; diagnosis of gastrointestinal bleeding.
III.D70-D77.D75.9 Disease of blood and blood-forming organs, unspecified
XI.K90-K93.K92.2 Gastrointestinal bleeding, unspecified
XI.K94.K94 * Diagnosis of diseases of the digestive tract
Contraindications:General clinical contraindications for radionuclide studies; pregnancy and lactation; children's age till 18 years.
Pregnancy and lactation:The drug is contraindicated in pregnancy and breastfeeding.
Dosing and Administration:Erythrocytes labeled with 51Cr are administered intravenously. Some of them are used for the preparation of the standard (1 ml of the erythrocyte suspension is diluted in 100 ml of 0.1% solution of stable sodium chromate). 15 minutes after the injection, 10-15 ml of blood is taken from the ulnar vein of the opposite hand of the patient with a heparinized syringe, from which 2 ml is used to determine the hematocrit and the remaining portion is taken for radiometry in a well counter. The volume of circulating erythrocytes is calculated by the formula: Nct × D × V × Ht / Nob, where Nct is the activity of the standard [pulses / (min × ml)]; D - dilution (100); V is the volume of the introduced suspension (ml); Ht - corrected hematocrit; Nob - the activity of the blood sample at 15 minutes [pulses / (min × ml)]. To determine the volume of deposited red blood cells, blood samples are taken at 10, 20, 40 and 60 minutes after intravenous administration of labeled erythrocytes. In the sample at 10 minutes (the rapidly circulating volume of red blood cells) and in the sample taken during the radioactivity period of the blood (t), the volume of circulating erythrocytes is calculated according to the above formula. The difference in the volume of circulating red blood cells at 10 minutes and at time t corresponds to the volume of deposited red blood cells in 1 ml of blood.
Determination of the lifespan of erythrocytes: intravenously at 5.55 MBq (0.15 mCi) or 3.7 MBq. At 2, 3, 7 and 10 days after intravenous administration of labeled erythrocytes from the patient's vein, 12 ml of blood is taken into the heparinized tubes. Immediately after taking 10 ml of blood, it is transferred to a counting tube and hemolyzed with saponin. Radiometry of blood samples is made in a well counter. The activity of the sample taken after 2 days is taken as 100%, and the remaining samples are expressed as a percentage of this sample. The obtained values are plotted on a semi-logarithmic coordinate system in which the time axis (in days) is plotted on a horizontal scale, and the radioactivity (in%) on a logarithmic scale on the ordinate axis. By the averaged line, the time to reduce radioactivity by 50% is found, which is an indicator of the lifespan of red blood cells, which is usually 22-31 days.
Side effects:Allergic reactions.
Special instructions:No data.