LMD IN DEXTROSE- dextran 40 injection, solution
LMD IN SODIUM CHLORIDE- dextran 40 injection, solution
10% LMD in 0.9% Sodium Chloride Injection (Dextran 40 in Sodium Chloride Injection, USP)
Low Molecular Weight Dextran for Intravenous Administration
Flexible Plastic Container
LMD (dextran 40) is a sterile, nonpyrogenic preparation of low molecular weight dextran (average mol. wt. 40,000) in 5% Dextrose Injection or 0.9% Sodium Chloride Injection. It is administered by intravenous infusion.
Also described as low viscous or low viscosity dextran, dextran 40 is prepared by acid hydrolysis and differential fractionation of a crude macromolecular polysaccharide produced from the fermentation of sucrose by the bacterium, Leuconostoc mesenteroides (strain B-512). The crude material is composed of linked glucose units. In the fraction represented by dextran 40, 80% of the molecules have a molecular weight ranging from 10,000 to 90,000 (average approximately 40,000) when measured by a light scattering method. More than 90% of the linkages are of the 1,6 alpha glucosidic, straight chain type.
Each 100 mL of 10% LMD (dextran 40) in 5% Dextrose Injection contains 10 g dextran 40 and 5 g dextrose hydrous in water for injection. Total osmolar concentration is 255 mOsmol/liter (calc.); pH is 4.4 (3.0 to 7.0).
Each 100 mL of 10% LMD (dextran 40) in 0.9% Sodium Chloride Injection contains 10 g dextran 40 and 0.9 g sodium chloride in water for injection. Total osmolar concentration is 310 mOsmol/liter (calc.); pH is 4.9 (3.5 to 7.0) (may contain sodium hydroxide and/or hydrochloric acid for pH adjustment). Electrolyte concentration per liter: Na+ 154 mEq; Cl- 154 mEq (not including ions for pH adjustment).
The solutions contain no bacteriostat, antimicrobial agent or added buffers (except for pH adjustment) and are intended only for single-dose injection. When smaller doses are required the unused portion should be discarded.
10% LMD (dextran 40) is an artificial colloid pharmacologically classified as a plasma volume expander; 5% Dextrose Injection is a fluid and nutrient replenisher; 0.9% Sodium Chloride Injection is a fluid and electrolyte replenisher.
Dextran 40 is a linear glucose polymer (polysaccharide) chemically designated (C6 H10 O5 )n .
The structural formula for dextran (repeating unit) is:
Dextrose, USP is chemically designated D-glucose monohydrate (C6 H12 O6 • H2 O), a hexose sugar freely soluble in water.
Sodium Chloride, USP is chemically designated NaCl, a white crystalline powder freely soluble in water.
Water for Injection, USP is chemically designated H2 O.
The flexible plastic container is fabricated from a specially formulated polyvinylchloride. Water can permeate from inside the container into the overwrap but not in amounts sufficient to affect the solution significantly. Solutions inside the plastic container also can leach out certain of the chemical components of the plastic in very small amounts before the expiration period is attained. However, safety of the plastic has been confirmed by tests in animals according to USP biological standards for plastic containers.
The fundamental action of LMD (dextran 40) is the enhancement of blood flow , particularly in the microcirculation. This enhancement is due to:
- Its primary effect of volume expansion with resultant hemodilution;
- Maintenance of the electronegativity of red blood cells;
- Coating of red blood cells and platelets;
- Increase in the suspension stability of blood;
- Decrease in the viscosity of blood.
It should be emphasized that the above effects are not exerted separately, but conjointly they result in the enhancement of blood flow.
LMD, used in the treatment of shock, produces significant increases in blood volume, central venous pressure, cardiac output, stroke volume, blood pressure and urinary output. It reduces blood viscosity, peripheral resistance and improves peripheral blood flow with the release of sequestered blood cells, thereby increasing venous return to the heart.
When used as part of the pump prime for extracorporeal procedures, LMD, as compared to whole blood, albumin 5%, or whole blood plus 5% dextrose and water, leads to less destruction of red blood cells and platelets, reduces intravascular hemagglutination and maintains erythrocyte electronegativity.
The infusion of LMD (dextran 40) during and after surgical trauma reduces the incidence of deep venous thrombosis (DVT) and pulmonary embolism (PE) in patients subject to surgical procedures with a high incidence of thromboembolic complication. Unlike antithrombogenic agents of the anticoagulant type, LMD does not achieve its effect so much by blocking fibrinogen-fibrin conversion but acts by simultaneously inhibiting other mechanisms essential to thrombus formation such as vascular stasis and platelet adhesiveness and by altering the structure and thereby the lysability of fibrin clots.
Histopathological studies have shown that the development of a mural platelet thrombus is the first stage of thrombus formation not only in the arterial, but also in the venous system. A number of studies have further shown that many patients who develop thromboembolic complications show an abnormally high platelet adhesiveness. Infusion of LMD has been shown to reduce platelet adhesiveness as measured by various in vitro tests on blood samples obtained from humans and to inhibit the growth of a mural platelet thrombus at the site of experimental (laser beam) injury in the rabbit’s ear chamber.
Studies have shown an increase in the lysability of thrombi formed in the presence of dextran. A consistent and characteristic alteration in fibrin structure has been observed when fibrin is formed in the presence of dextran, and further experiments demonstrated such fibrin to be more susceptible to plasmin digestion. Other studies have shown that dextran infused into patients during surgery increases the lysability of ex vivo thrombi. Controlled clinical trials have shown that thrombi in patients treated with dextran have a more pronounced tendency to undergo lysis as determined by phlebography.
LMD is evenly distributed in the vascular system. Its distribution according to molecular weight shifts toward higher molecular weights as the smaller molecules are excreted by the kidney. In normovolemic subjects, approximately 50% is excreted within 3 hours, 60% is excreted within 6 hours and about 75% within 24 hours. Reabsorption of dextran by the renal tubules is negligible. The unexcreted molecules of dextran diffuse into the extravascular compartment and are temporarily taken up by the reticuloendothelial system. Some of these molecules are returned to the intravascular compartment via the lymphatics. Dextran is slowly degraded by the enzyme dextranase to glucose.
Solutions containing carbohydrate in the form of dextrose restore blood glucose levels and provide calories. Carbohydrate in the form of dextrose may aid in minimizing liver glycogen depletion and exerts a protein sparing action. Dextrose injected parenterally undergoes oxidation to carbon dioxide and water.
Sodium chloride in water dissociates to provide sodium (Na+) and chloride (Cl-) ions. Sodium (Na+) is the principal cation of the extracellular fluid and plays a large part in the therapy of fluid and electrolyte disturbances. Chloride (Cl-) has an integral role in buffering action when oxygen and carbon dioxide exchange occurs in red blood cells. The distribution and excretion of sodium (Na+) and chloride (Cl-) are largely under the control of the kidney, which maintains a balance between intake and output.
Water is an essential constituent of all body tissues and accounts for approximately 70% of total body weight. Average normal adult daily requirement ranges from two to three liters (1.0 to 1.5 liters each for insensible water loss by perspiration and urine production).
Water balance is maintained by various regulatory mechanisms. Water distribution depends primarily on the concentration of electrolytes in the body compartments and sodium (Na+) plays a major role in maintaining physiologic equilibrium.
LMD (dextran 40) is indicated for use in the adjunctive treatment of shock or impending shock due to hemorrhage, burns, surgery or other trauma. It is not indicated as a replacement for whole blood or blood components if they are available. It should not replace other forms of therapy known to be of value in the treatment of shock.
LMD is also indicated for use as a priming fluid, either as a sole prime or as an additive, in pump oxygenators during extracorporeal circulation.
LMD is also indicated for use in prophylaxis of venous thrombosis and pulmonary embolism in patients undergoing procedures known to be associated with a high incidence of thromboembolic complications, such as hip surgery.
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