Heparins

Question 1

use of anticoagulants

Answer 1

prevent thrombus formation or extension of existing thrombus in slower-moving venous side of circulation, where thrombus consists of fibrin web enmeshed with platelets & red cells

Question 2

Heparin initiates

Answer 2

anticoagulation rapidly but has short duration of action.
~ often referred to as ‘standard’ or heparin (unfractionated) to distinguish it from LMW heparins, which have a longer duration of action. Although LMW heparin is generally preferred for routine use, heparin (unfractionated) can be used in those at high risk of bleeding because its effect can be terminated rapidly by stopping the infusion.

Question 3

Low molecular weight heparins

Answer 3

~ dalteparin sodium, enoxaparin sodium, & tinzaparin sodium
~ preferred over heparin (unfractionated) in prevention of VTE as effective + lower risk of HIT.
~ standard prophylactic regimen does not require anticoagulant monitoring. ~ duration of action longer than that of heparin (unfractionated) & once-daily subcutaneous administration possible for some indications, making them convenient to use.

~ LMW heparins are generally preferred over heparin (unfractionated) in treatment of DVT & PE, & also used for prevention of clotting in extracorporeal circuits

Question 4

Heparinoids

Answer 4

Danaparoid sodium
~ used for prophylaxis of DVT in patients undergoing general or orthopaedic surgery. Providing there is no evidence of cross-reactivity, it also has a role in patients who develop heparin-induced thrombocytopenia.

Question 5

Argatroban

Answer 5

~ oral anticoagulant
~ should only be started once thrombocytopenia has substantially resolved.

Question 6

Fondaparinux sodium

Answer 6

synthetic pentasaccharide that inhibits activated factor X

Question 7

Epoprostenol

Answer 7

(prostacyclin) given to inhibit platelet aggregation during renal dialysis when heparins unsuitable or contra-indicated
~ also licensed for tx of primary pulmonary hypertension resistant to other tx, usually with oral anticoagulation;
~ ` initiated by specialists in pulmonary hypertension
~ potent vasodilator
~ short half-life of ~3 minutes
~ MUST be administered by continuous IV infusion.

Question 8

Heparins flushes

Answer 8

~ use of heparin flushes should be kept to minimum.
~ For maintaining patency of peripheral venous catheters, sodium chloride injection 0.9% is as effective as heparin flushes.
~ role of heparin flushes in maintaining patency of arterial & central venous catheters unclear.

Question 9

Hirudins

Answer 9

Bivalirudin, hirudin analogue
~ thrombin inhibitor
~ licensed for unstable angina or NSTEMI in patients planned for urgent or early intervention, & as anticoagulant for patients undergoing percutaneous coronary intervention (+ patients with STEMI undergoing primary percutaneous coronary intervention