Episode 6 - Anticoagulants, Thrombolytics (Fibrinolytics), Antiplatelet Agents and Antifibrinolytics

Question 1

What are anticoagulants?

Answer 1

Substances that prevent the synthesis of a fibrin network which inhibits coagulation and the formation of thrombi.

Question 2

How fast do anticoagulants work and what does this mean with regards to how they should be used?

Answer 2

IV will work within minutes and orally will work within hours.Because immediate defect these should be used with great caution.sufficient therapy and hemorrhagic risk is narrow and varies considerably patient to patient.

Question 3

Anticoagulants are divided into 4 groups:

Answer 3

1 indirect thrombin inhibitors (basically heparin)
2 Coumarin Anticoagulants (basically Warfarin)
3 Direct thrombin inhibitors4 Direct factor X inhibitors

Question 4

Commercial Heparin is actually a mixture of Heparins. The two most common mixtures are what?

Answer 4

1 Unfractionated Heparin (UFH) - Heparin Sodium

2 Low-molecular-weight heparin (LMWH) - Fragmin, innohep, lovenox

Question 5

How the crap does Heparin work?

Answer 5

Heparin stimulates antithrombin-3, which in turn neutralizes the activity of factor 10 (as well as other clotting factors. With no 10 no prothrombin to thrombin, and eventually no fibrinogen to fibrin (indirect thrombin inhibitor)*also stimulates heparin cofactor 2 which inhibits thrombin

Question 6

What is unfractionated heparin (UFH)?

Answer 6

Effective parenteral anticoagulant. Binds to plasma proteins, which reduces its anticoagulation activity and causes large anticoagulatant response. Also binds to endothelial cells and macrophages

Question 7

What test is used to monitor UFH and its clinical effectiveness?

Answer 7

Activated partial thromboplastin time (APTT)

Will typically prolong APTT to 2-2.5 time that of normal value

Question 8

Why is Low Molecular Weight Heparins useful?

Answer 8

Can be given in hospital or out of hospital. Administered SC (sub-cutaneous) and doesn’t need laboratory monitoring.

Question 9

What is the only major coumarin anticoagulant found in in the US of A? And whats the fun nugg related to warfarin?

Answer 9

warfarin (Coumadin)main active ingredient in many rodent poisons which will can lead to death by hemorrhage and internal bleeding

Question 10

How does warfarin work?

Answer 10

interferes with hepatic synthesis of vit K dependent clotting factors (2, 7,9,10)

Question 11

What is the target INR for most patients using warfarin?

Answer 11

should be adjusted to acheive INR=2.0-3.0

Question 12

DDI (drug-drug interactions): what agents inhibit warfarin metabolism?

Answer 12

Cimetidine (Tagamet)
Acetaminophen (Tylenol)
High dose, acute alcohol
Azithromycin (Zithromax)
Ciprofloxacin
Clarithromycin
Erythromycin

Question 13

DDI: which drugs stimulate warfarin metabolism?

Answer 13

Chronic alcohol usephenytoin (dilantin)oral contraceptives increase the synthesis of many clotting factors and can reduce the effect of warfarin

Question 14

How can diet effect warfarin?

Answer 14

food rich in vit K result in effects in warfarin

Question 15

What is the most common side effect of warfarin?

Answer 15

Bleeding that occurs most often in the mucous membranes of GI tract and GU tract. Warfarin is contraindicated during pregnancy because is crosses the placenta. Breast feeding should also be avoided

Question 16

What was the first oral direct thrombin inhibitor? Why is it so snazzy?

Answer 16

Dabigatran (Pradaxa)orally administered, doesn’t require frequent blood tests for INR.

Question 17

Daily DoubleThe only thing mentioned about Direct factor X inhibitors was: when was the first of its kind released?

Answer 17

Aug-11

Question 18

What is the mechanism which thrombolytics work? (Fibrinolytics are mentioned here i’m assuming say type of mech used)

Answer 18

Thrombolytics rapidly lyse thrombi when administered intravenously by catalyzing the formation of plasmin from plasminogen

Question 19

What are some example of Thrombolytics?

Answer 19

Streptokinase, urokinase, synthetic tPA

Question 20

What are the three classes of anti-platelet agents?

Answer 20

Cyclooxygenase inhibitors (mainly aspirin) cox blockerThienopyridines (ADP inhibitors)GP IIa/IIIa inhibitors

Question 21

What is the mechanism by which aspirin works?

Answer 21

Inhibits the synthesis of TXA2

Question 22

What does thienopyridines (ADP Inhibitor) and what is the main drug that fits into this category?

Answer 22

Prevent ADP from binding to their receptors on platelets.Main Drug: clopidogrel (Plavix)

Question 23

What does GP IIb/IIIa inhibitors do and what is an example of this drug?

Answer 23

Inhibit the activation of glycoprotein IIb/IIIa receptors on plateletsExample of drug: abciximab (ReoPro)

Question 24

Take a break

Answer 24

Tooshie squeezes all around

Question 25

What does antifibrinolytics do and a where is it used in denistry?

Answer 25

Tranexamic acid inhibits the activation of plasminogen to plasmin.Dental: tranexamic acid is used in the form of 5% mouth wash after extraction or surgery with prolonged bleeding.