Pharma 8.1 - Anticoagulants Flashcards Preview

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Flashcards in Pharma 8.1 - Anticoagulants Deck (13):
1

What type of clot tends to form in arteries vs veins?
What would you use to clear each type of clot?

Arteries - White clots, thrombolytics/anti-platelets
Veins - Red clots, Anti-coagulants

2

What is Virchow’s triad?
Name 2 causes of each element.

Hyper-coagulability (smoking, malignancy).
Endothelial damage (atheroma, hypertension).
Stasis (immobility, cardiac abnormality such as AF).

3

What are the 2 pathways of the clotting cascade?
What activates each pathway?

Intrinsic pathway - Kallikrein > exposed collagen, .
Extrinsic pathway - Tissue damage > thromboplastin.

4

What 3 types of drug potentiate warfarin?
Name some drugs in each category.

Hepatic metabolism inhibitors - Amiodarone, metronidazole quinolone, cimetidine, alcohol.
Platelet function inhibitors - aspirin.
Drugs which reduce Vitamin K from gut bacteria - Cephalosporin antibiotics

5

Name 3 drugs which inhibit warfarin?

Antiepileptics.
Rifampicin.
St John’s Wort.

6

What INR ranges are aimed for with different warfarin indications?

INR of 2-3 in DVT, PE, AF
INR of 2.5-4.5 in mechanical valves and patients on warfarin with recurrent thrombosis.

7

What 2 ways are there of reversing warfarin OD? What is the difference between them?

IV Vit K - for brief episode.
Fresh Frozen plasma - for severe episode.

8

What is the mechanism of action of warfarin?
4 indications?
5 contraindications?
4 ADRs?
How long does warfarin take to start working? Why? How would you account for this clinically?

MoA - Prevents the reduction of vitamin K preventing it from activating clotting factors mainly in the intrinsic pathway.
Indications - DVT, PE, AF, mechanical heart valves.
Contraindications - Drugs which induce/inhibit CYP450, liver disease, pregnancy, drugs which would displace it from albumin (normally highly bound to albumin), cranberry/grapefruit juice.
ADRs - Local bruising/bleeding, IC haemorrhage, anaemia (from GI loss), teratogenicity
A couple of days, as it prevents production of new clotting factors in the liver, but there are still clotting factors in circulation which must be broken down before the effects of warfarin will be noticed. Give Heparin immediately to account for this.

9

Give 2 examples of heparins.
What is the difference in the administration of different types?
What is their mechanism of action?
3 indications?
1 contraindications?
2 ADRs?

Unfractionated, low molecular weight.
Unfractionated is given IV, LMW is given subcut.
MoA - Unfrac is large enough to inhibit multiple parts of the coagulation cascade including thrombin, whereas LMW is only large enough to inhibit 1 site and not thrombin.
Indications - Pre-Warfarin, peri-operative cover, pregnancy in place of warfarin,
Contraindications - Renal failure (LMW)
ADRs - Thrombocytopenia (unfrac), bruising/bleeding/haemorrhage, osteoporosis

10

How would you treat thrombocytopenia from heparin?

Stop heparin, give hirudin.

11

How do you reverse the effects of heparin?

Stop heparin, give protamine.

12

Give 4 examples of anti-platelets.
What is their mechanism of action?
4 indications?
1 ADR?

Aspirin, dipyridamole, clopidogrel, glycoprotein IIb/IIIa inhibitors.
MoA - Prevention of platelet activation.
Indications - ACS/NSTEMI (clopidogrel for 1 year), prevention of stroke (dipyridamole), high risk ACS and poor PCI (GP IIa/IIIa receptor antag).
ADRs - Bruising/bleeding

13

What are the 3 stages of haemostats?

Blood vessel constriction.
Formation of a platelet plug.
Formation of a clot.