Hema Drugs

Question 1

Difference of arterial and venous thrombi.

Answer 1

Arterial thrombi- rich in platelets because of the high shear in the injured arteries.

Venous thrombi- form under low shear conditions, contain relatively few platelets and are predominantly composed of fibrin and trapped red cells.

Question 2

Platelets are maintain in an inactive state by ___.

Answer 2

Nitric oxide and prostacycline released by endothelial cells lining the blood vessels.

Question 3

MOA of aspirin

Answer 3

Irreversibly acetylating and inhibiting platelet COX1, a critical enzyme in the biosynthesis of thromboxane A2.

Question 4

True or false. Prasugrel is about tenfold more potent than clopidogrek and has a more rapid onset of action because of better absorption and more streamlined metabolic activation.

Answer 4

True.

Question 5

Clopidogrel and prasugrel should be stopped ___ before major surgery.

Answer 5

5-7 days

Question 6

Concomitant administration of clopidogrel with PPI, which are inhibitors of ___ , produces a small reduction in the inhibitory effects of clopidogrel on ADP-induced platelet aggregation.

Answer 6

CYP2C19

Question 7

True or false. Ticagrelor does not require metabolic activation and it produces reversible inhibition of the ADP receptor.

Answer 7

True

Question 8

What is true regarding dosing of Ticagrelor?
A. Initiated with an oral loading dose of 180mg followed by 90mg BID
B. Does not require adjustment in patients with renal impairment
C. Used with caution in patients with hepatic disease
D. All of the above

Answer 8

D.

Question 9

Most common side effect of ticagrelor

Answer 9

Dyspnea and asymptomatic ventricular pauses

Question 10

Ticagrelor should be stopped ___ prior to major surgery.

Answer 10

5-7 days

Question 11

MOA of heparin.

Answer 11

Activating antithrombin and accelerating the rate at which antithrombin inhibits clotting enzymes, particularly thrombin and factor Xa.

Question 12

True or false. Heparin clearance is mainly extrarenal.

Answer 12

True. Heparin binds to macrophages, which intenalize and depolymerize the long heparin chains and secrete shorter chains back into the circulation.

Question 13

Dosing of heparin.

Answer 13

For prophylaxis:
5000 units SQ 2-3x daily

For ACS:
After IV heparin bolus of 5000 units or 70units/kg, a heparin infusion rate of 12-15 units/kg per hr is administered.

For VTE:
Initial,bolus of 5000units or 80units/kg, followed by infusion of 18 units/kg per hr.

Question 14

True or false. Heparin has a dose-dependent clearance.

Answer 14

True

Question 15

Features of Heparin-Induced Thrombocytopenia.
A. Platelet count of <100,000/ul or a decrease in platelet count of >50%
B. Plt count falls 5-10 days after starting heparin
C. More common with unfractionated heparin then LMWH
D. More common in surgical patients and patients with cancer than general medical patients
E. More common in women
F. Venous thrombosis more common than arterial thrombosis
G. All of the above

Answer 15

G. All of the above

Question 16

The most specific diagnostic test for HIT.

Answer 16

Serotonin release assay

Question 17

Treatment with therapeutic doses of heparin for ___ can cause a reduction in bone density.

Answer 17

> 1 month

Question 18

True or false. LMWH catalyzes factor Xa inhibition by antithrombin more than thrombin inhibition.

Answer 18

True

Question 19

True or false. LMWH does not require coagulation monitoring.

Answer 19

True.
Indications for LMWH monitoring include renal insufficiency and obesity; those with mechanical heart valves; children and infants.

Question 20

Half-life of Fondaparinux

Answer 20

17 hours

Question 21

True or false. Fondaparinux does NOT cause HIT.

Answer 21

True

Question 22

Target INR in warfarin therapy.

Answer 22

For most indication: INR 2-3

For those with mechanical heart valves: 2.5 to 3.5

Question 23

Treatment in asymptomatic patients treated with warfarin with INR 3.5 to 10.

Answer 23

Withholding of warfarin until INR returns to therapeutic range

Question 24

Treatment among warfarin-treated patients with INR >10

Answer 24

Oral vitamin K 2.5-5mg

Question 25

Skin necrosis, a rare complication of warfarin is seen___

Answer 25

2-5 days after initiation of therapy

Question 26

True or false. Warfarin crosses the placenta, but does not pass into the breast milk.

Answer 26

True

Question 27

Thrombophylaxis with rivaroxaban and apixaban after elective hip or knee replacement surgery.

Answer 27

Rivaroxaban- 10mg once daily
Apixaban- 2.5mg twice daily

Given for 14 days after knee arthroplasty and for 35 days after hip arthroplasty.

Question 28

True or false. Vitamin K is of no benefit in bleeding from DOACs.

Answer 28

True