Dextran

What is Dextran?

Dextran is a complex, branched polysaccharide (a type of sugar molecule) that is widely used in medicine as a plasma volume expander. It is synthesized by certain bacteria from sucrose and then processed into various molecular weights for pharmaceutical use. The two most common forms are Dextran 40 and Dextran 70, referring to their average molecular weights of 40,000 and 70,000 Daltons, respectively. Administered intravenously, Dextran solutions are crucial in managing conditions where there is a significant loss of blood volume or impaired circulation.

Unlike blood products, Dextran is a synthetic colloid solution, meaning it contains large molecules that cannot easily pass through capillary walls. This property allows it to remain in the bloodstream for an extended period, effectively drawing fluid into the vascular space and increasing circulating blood volume. Its role extends beyond simple volume expansion, offering additional benefits related to blood viscosity and platelet function.

How Does it Work?

The primary mechanism of action of Dextran involves its osmotic properties. When infused into the bloodstream, its large molecules create an osmotic gradient that draws water and electrolytes from the interstitial (extracellular) space into the intravascular compartment. This rapid shift of fluid leads to an increase in plasma volume, which helps to restore blood pressure and improve cardiac output, particularly in patients experiencing hypovolemic shock.

Beyond its volume-expanding capabilities, Dextran also exerts beneficial effects on blood flow and rheology. It reduces blood viscosity by coating red blood cells and platelets, decreasing their tendency to aggregate. This anti-aggregation effect, coupled with its ability to coat the endothelial lining of blood vessels, contributes to its properties as an antithrombotic agent. Specifically, Dextran 40 is particularly effective in improving microcirculation due to its smaller molecular size, allowing it to penetrate smaller capillaries and reduce sludging of red blood cells, which is vital in preventing ischemic damage.

The body eliminates Dextran primarily through renal excretion. Smaller molecules (like Dextran 40) are filtered more rapidly by the kidneys, while larger molecules (like Dextran 70) are metabolized more slowly by dextranase enzymes before excretion, contributing to their longer plasma half-life.

Medical Uses

Dextran has several important medical applications, primarily focused on emergency and surgical settings:

• Treatment of Hypovolemic Shock

  One of the most critical uses of Dextran is in the rapid treatment of hypovolemic shock resulting from severe hemorrhage, burns, trauma, or major surgery. It quickly restores circulating blood volume, stabilizing blood pressure and improving tissue perfusion until blood products or other definitive treatments can be administered.

• Prevention of Thromboembolism

  Due to its antithrombotic properties, Dextran (especially Dextran 40) is used to prevent venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE), particularly after high-risk surgeries like hip replacement. It achieves this by decreasing platelet adhesiveness and aggregation, and by coating the vascular endothelium, which hinders clot formation.

• Improvement of Microcirculation

  In vascular surgery and re-implantation procedures, Dextran 40 is invaluable for improving blood flow in small vessels, reducing the risk of thrombosis and maintaining the viability of reattached tissues or organs. It prevents the aggregation of red blood cells and platelets that can otherwise impede capillary flow.

• Adjunct in Surgical Procedures

  It can be used during certain surgical procedures to maintain blood volume and reduce the risk of postoperative complications related to poor circulation.

Dosage

The dosage of Dextran is highly individualized and depends on the patient's condition, weight, the type of Dextran (40 or 70), and the clinical indication. It is always administered via intravenous infusion under strict medical supervision.

• For Hypovolemic Shock

  Typically, a rapid initial infusion (e.g., 500-1000 mL for adults) is given to quickly restore blood volume. Subsequent doses are adjusted based on the patient's response, vital signs, central venous pressure, and urine output. The total daily dose usually does not exceed 20 mL/kg body weight for Dextran 70 or 10 mL/kg for Dextran 40, to minimize the risk of adverse effects.

• For Thromboembolism Prophylaxis

  Lower doses are used, often starting with an initial infusion on the day of surgery, followed by daily infusions for a few days post-operatively. For example, Dextran 40 might be given at 500 mL on the day of surgery and then 500 mL daily for 2-3 days, or every other day for up to two weeks.

It is crucial to monitor renal function, fluid balance, and coagulation parameters during Dextran therapy. Contraindications include severe congestive heart failure, renal failure with oliguria or anuria, and known hypersensitivity to Dextran.

Side Effects

While generally safe when used appropriately, Dextran can cause side effects, ranging from mild to severe:

• Common Side Effects

  Nausea, vomiting, fever, chills, and mild skin reactions such as rash or itching are sometimes observed. These are usually transient and resolve without intervention.

• Serious Allergic Reactions (Anaphylaxis)

  The most serious potential side effect is an anaphylactic or anaphylactoid reaction, which can be life-threatening. Symptoms include severe hypotension, bronchospasm, urticaria, angioedema, and even cardiac arrest. The incidence of severe reactions is relatively low but can occur. To reduce this risk, a small test dose or pre-treatment with a hapten Dextran solution (e.g., Dextran 1) may be administered prior to the main infusion to neutralize antibodies.

• Renal Impairment

  High doses or rapid infusion of Dextran, especially in dehydrated patients or those with pre-existing renal issues, can lead to osmotic nephrosis and acute kidney injury. Adequate hydration is essential.

• Fluid Overload

  As a potent volume expander, Dextran can cause fluid overload, particularly in patients with impaired cardiac or renal function, leading to pulmonary edema or congestive heart failure.

• Coagulopathy

  Dextran can interfere with blood coagulation, increasing bleeding time and potentially leading to hemorrhagic complications, especially at higher doses or in patients with pre-existing bleeding disorders.

Drug Interactions

Dextran can interact with certain medications, requiring careful consideration:

• Anticoagulants and Antiplatelet Agents

  Concomitant use with anticoagulants (e.g., warfarin, heparin) or antiplatelet drugs (e.g., aspirin, clopidogrel) can significantly increase the risk of bleeding due to Dextran's own antiplatelet and fibrinolytic effects.

• Other Plasma Volume Expanders

  Combining Dextran with other colloid solutions or crystalloids should be done cautiously to avoid fluid overload and electrolyte imbalances.

• Drugs Affecting Renal Function

  Medications that are nephrotoxic or affect kidney function may exacerbate the risk of renal impairment when used with Dextran.

• Blood Typing and Cross-matching

  Dextran can interfere with blood typing and cross-matching procedures, potentially leading to false results. It is recommended to draw blood samples for these tests before initiating Dextran infusion.

FAQ

Q: Is Dextran a blood product?

A: No, Dextran is not a blood product. It is a synthetic polysaccharide solution, manufactured from bacterial fermentation. It serves as a blood substitute or plasma volume expander but does not contain blood cells or plasma proteins.

Q: How quickly does Dextran start working?

A: Dextran acts very rapidly. Its volume-expanding effects are typically observed within minutes of intravenous infusion, making it highly effective in emergency situations requiring immediate volume restoration.

Q: Can Dextran be used for long-term treatment?

A: Generally, Dextran is intended for short-term use, primarily in acute emergencies, during surgery, or for short-term prophylaxis. Prolonged or high-dose use increases the risk of side effects like renal impairment and coagulopathy.

Q: What is the main difference between Dextran 40 and Dextran 70?

A: The main difference lies in their average molecular weights. Dextran 40 (40,000 Daltons) has a shorter half-life and is more effective at improving microcirculation and preventing platelet aggregation due to its smaller size. Dextran 70 (70,000 Daltons) has a longer half-life and is primarily used for sustained plasma volume expansion.

Products containing Dextran are available through trusted online pharmacies. You can browse Dextran-based medications at ShipperVIP or Medicenter.

Summary

Dextran is a vital pharmaceutical agent recognized for its efficacy as a plasma volume expander and its beneficial effects on blood rheology and coagulation. Available in different molecular weights, primarily Dextran 40 and Dextran 70, it plays a crucial role in managing hypovolemic shock, preventing thromboembolism, and improving microcirculation in various medical and surgical contexts. While offering significant therapeutic advantages, its administration requires careful consideration of dosage, potential side effects—especially anaphylaxis and renal impairment—and drug interactions. Always administered under strict medical supervision, Dextran remains an indispensable tool in critical care and surgical medicine, contributing significantly to patient outcomes when used appropriately.