Question

MD03b [Jul97] Heparin:

A. Has a half life dependent on dose
B. Inactivates factors XII, XI, X, IX
C. ?
D. ?
E. ?

Answer 1

MD03 [Mar96] [Jul97] [Jul98] Regarding the plasma half-life of heparin is Less for low MW heparins.

Therefore, correct answer is C. Less for low MW heparins

Step-by-step explanation:

The plasma half-life of heparin is influenced by the molecular weight (MW) of the heparin molecule. Low MW heparins have a shorter plasma half-life compared to high MW heparins. This is a crucial factor in determining the duration of anticoagulant effects and clinical management.

Heparin, a potent anticoagulant, is eliminated from the body by a combination of renal and non-renal mechanisms. The clearance of heparin is influenced by its molecular weight. Low molecular weight heparins (LMWH) have a shorter plasma half-life compared to unfractionated heparin (UFH). This is because LMWH undergoes less renal clearance and has reduced binding to endothelial cells, resulting in a more predictable and shorter duration of action. In contrast, the plasma half-life of UFH is longer and more variable due to greater renal clearance and binding to endothelial cells.

Therefore, correct answer is C. Less for low MW heparins

Your question is incomplete, but most probably your full question was MD03 [Mar96] [Jul97] [Jul98] Regarding the plasma half-life of heparin:

A. Clearance affected by warfarin

B. Depends on site of injection

C. Less for low MW heparins

D. Depends on dose given

E. ?

Answer 2

Heparin is a dose-dependent anticoagulant that inactivates clotting factors XII, XI, X, and IX and opposes the conversion of prothrombin to thrombin, thus preventing blood clots.

Step-by-step explanation:

The student's question pertains to heparin, which is an anticoagulant substance used medicinally to prevent blood clots. First, heparin does have a half-life that is dependent on the dose given; this means that the rate at which heparin is eliminated from the plasma and therefore the duration of its effect can vary based on the size of the dose administered. Second, heparin works by inactivating several factors in the clotting process, including factors XII, XI, IX, and X, and it opposes the conversion of prothrombin (factor II) into thrombin in the common pathway. It is important to note that while basophils release heparin naturally, a pharmaceutical form of heparin is often administered to patients, such as those undergoing surgery who are at risk for blood clots.