NAPLEX Question of the Week: Deciphering Dextran

Testing your knowledge on dextran is the subject of our Question of the Week!
NAPLEX Question of the Week: Deciphering Dextran
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A 65-year-old female patient with a history of peripheral artery disease (PAD) is scheduled to undergo a peripheral angioplasty procedure. The patient has a known allergy to iodinated contrast agents. The healthcare team is considering a low molecular weight dextran as an alternative.

Which of the following statements regarding low molecular weight dextran is correct? Select all that apply.

A) Low molecular weight dextran is a glucose polymer derived from starch.

B) Low molecular weight dextran enhances blood viscosity and improves microcirculation.

C) Low molecular weight dextran should initially be given in a test dose due to risk of anaphylactoid reaction.

D) Low molecular weight dextran is contraindicated in patients with creatinine clearance < 50ml/min.

E) Low molecular weight dextran can increase the risk of bleeding.

Rationale:

Answer A is correct. Low molecular weight dextran is indeed a synthetic polymer derived from starch. It is produced by the hydrolysis of high molecular weight dextran.

Answer B is correct. Low molecular weight dextran has the ability to enhance blood viscosity and improve microcirculation. It does so through a number of mechanisms including by increasing plasma volume, reducing blood cell aggregation, and maintaining electronegativity of red blood cells. 

Answer C is incorrect. Low molecular weight dextran is generally well-tolerated and does not commonly cause anaphylactic reactions. However, allergic reactions and hypersensitivity can occur and initial administration should be monitored for these potential reactions. Test doses however are not recommended for this product, but are sometimes administered with another common dextran product-iron dextran. 

Answer D is incorrect. Low molecular weight dextran is not contraindicated in all patients with renal impairment. Unlike high molecular weight dextran, which is primarily eliminated by the kidneys and can accumulate in renal dysfunction, low molecular weight dextran is eliminated mainly through the reticuloendothelial system and does not pose as significant of a risk to patients with renal impairment. However any dextran product should be avoided in patients with severe renal impairment noted by severe oliguria or anuria

Answer E is correct. Low molecular weight dextran can increase the risk of bleeding. It impairs platelet function and coagulation factors, leading to prolonged bleeding time. It should be used with caution in patients with a bleeding tendency or those undergoing surgical procedures with a high risk of bleeding complications. It is contraindicated in patients with known hemostatic defects, such as thrombocytopenia. 

LMD in Dextrose Package Insert

NAPLEX competencies covered

  • 2.1 – Pharmacology, mechanism of action, or therapeutic class
  • 2.3 – Boxed warnings or REMS
  • 3.7 – Adverse Drug effects, toxicology, or overdose

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