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Dextra has the generic name Dextra 40 is classified as a plasma substitute drug. The drug is indicated for the treatment of iron deficiency anemia in people who cannot take iron due to side effects or anemia due to ineffective treatment.
1. Mechanism of action of the drug Dextra
What is Dextra? Dextra belongs to the group of plasma substitutes and is available as a low molecular weight Dextran solution. The calculated mean molecular weight in Dextra 40 is approximately 40000. Dextran solution has a rapid increase in circulating volume or maintains it for a period of 3 to 4 hours. In addition, Dextran solution also helps to improve microcirculation to prevent lacunae conditions that do not affect blood types.
When Dextran drug enters the body due to higher osmotic pressure than plasma, fluid from the interstitial space is pulled into the intravascular space. Therefore, this process will increase the volume of circulation corresponding to each dextran in the circulation that can bind with 20 to 25 ml of water.
Mechanism of action of Dextran solution:
When Dextran solution is introduced into the body, the circulating blood volume will increase and after only about 15 minutes, the effect of the drug will be clearly seen with the expression in the blood. Dextran's molecular weight increased to 70,000. After 4 hours of using the drug, almost the effect of increasing circulating volume will disappear, then the blood volume replaced by Dextran with molecular weight of 40000 will return to normal.
Due to the low molecular weight of Dextran, it has a strong ability to bind to water molecules, so it helps to improve the rheological properties of the blood and at the same time can produce specific effects on the microcirculation when desired. perform situations such as increasing fluid delivery to tissue or increasing tissue oxygenation... This process can thin the blood or decrease blood viscosity or increase cardiac output while decreasing peripheral resistance. Furthermore, with platelet aggregation it is possible that the formation of a fibrinogen-fibrin complex is inhibited and reversed. Therefore, through the effect of low molecular weight Dextran solution, it is also often used in the treatment of thromboembolism.
The elimination half-life of Dextra is approximately 8 hours, and the molecular volume of this solution is distributed between 6 and 7 liters in the intravascular space. Dextra is rapidly excreted by the kidneys in the first hours after infusion and then the rate slows down. Dextran solutions with a molecular weight of 15,000 or less are likely to be eliminated by the kidneys. Or lower molecular weight Dextran molecules are also eliminated by the kidneys. Approximately 70% of the drug with a dose of Dextra 40 is excreted unchanged in the urine 24 hours after infusion. However, dextran molecules with a molecular weight greater than 50,000 are not eliminated by the kidneys, but are slowly converted to glucose for further conversion to carbon dioxide and water.
2. Dosage and how to use Dextra
Dextra is effective in the treatment of iron deficiency in the blood and is often indicated in the following cases:
Shock, hypovolemia and microcirculation due to blood loss, trauma, poisoning, burns , infection, pancreatitis Peritonitis . Prevention of surgical shock, prevention of post-operative and post-traumatic embolism. Improves local circulation, while reducing the risk of thrombosis during organ transplantation. In addition, the drug Dextra is also added to the infusion solution of the heart-lung machine in open-heart surgery.
Dextra is used in dosages depending on each case as well as each clinical requirement. Dextran content, drug infusion rate should be calculated by the doctor in accordance with each patient's condition.
During infusion it is necessary to closely monitor arterial pressures and central venous pressures. In the case of infusion of Dextra for dehydrated patients, the doctor should prescribe additional electrolytes and water.
Some suggestions on the content of Dextra in treatment:
Treatment of hemorrhagic shock or prevention: The starting dose is from 500 to 1500 ml corresponding to 10 to 30ml/kg body weight/day, and the speed infusion from 40 to 80 drops/minute corresponds to 120 to 240 ml/hour. For the treatment of thromboembolism after surgery or after trauma: Use a dose of 500 to 1500 ml corresponding to 10 to 20 ml/kg body weight/day, and an infusion rate of 40 to 80 drops/min corresponding to 120 to 240 ml/hour. If the patient is at high risk of thrombosis with spinal fractures or intra-abdominal or prostate cancer, immobilized for a long time, people with a history of thrombosis... can also use it. use this dose in treatment. The maximum recommended dose for children is 15ml/kg body weight/day. For the use case for the preparation of the cardiopulmonary bypass machine in cardiac surgery, the amount of Dextran 40 can change the volume of the machine. Dextran 40 with a concentration of 10% will be injected into the blood vessels at a dose of 1 to 2 grams/kg body weight, corresponding to a concentration of 10 to 20 mg/kg, the total dose should not exceed 2 grams/kg equivalent. equivalent to 20ml/kg. These dosage suggestions are for reference only. Therefore, if you use Dextra for treatment, you need to learn about the drug carefully, and at the same time must be consulted and prescribed to use according to the doctor's prescription.
In case of overdose, Dextra may cause circulatory overload such as pulmonary edema or congestive heart failure. In addition, overdosage should be avoided in patients with pre-existing renal impairment and the dose should be adjusted according to the degree of renal impairment. If signs of oliguria are observed along with a syrupy consistency, the drug must be discontinued and appropriate diuretics or fluids may be used.
3. Unwanted side effects and some notes when using Dextra
Dextra may be contraindicated in some cases such as:
Decompensated heart failure with risks of circulatory overload Patients with pulmonary edema Cerebral hemorrhage Oliguria, anuria, kidney damage Local bleeding Extracellular fluid loss/reduction, Thrombocytopenia People with a history of hypersensitivity to Dextran. Use of Dextra may cause some rare unwanted side effects such as systemic reactions causing anaphylaxis or fever.
In patients with hypersensitivity to Dextran, this can often occur at the very beginning of the infusion, or the first time using the drug. This rate of sensitization can be reduced if the patient is given Dextran 1 prior to the infusion of Dextran 40.
Acute renal failure may occur with the side effects of Dextra. This rate is higher in people with prior kidney damage. Pathogenesis of renal dysfunction in treatment with Dextra 40 due to the process of increasing the viscosity in the renal tubules, and at the same time reducing the flow through the renal tubules, causing the kidneys to absorb the colloid into the tubular cells with a moist body. cell. This situation can cause direct damage to the renal tubular epithelium. Therefore, when using Dextra, it is necessary to closely monitor kidney function so that it can be treated promptly.
Drug Interactions Dextra may increase the nephrotoxic effect of aminoglycosides when used concurrently. Therefore, you should avoid using the same two drugs on the same course of treatment. In addition, Dextra also affects the coagulation balance by different mechanisms. Therefore, when combined treatment with Dextra with anticoagulant drugs can cause a tendency to hemophilia... This situation can be explained through the process of Dextra interacting with factor VIII causing disturbances. Blood clotting disorders occur in people with factor VIII deficiency.
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