Pharmacology Anticoagulants

Question 1

Lab evaluation of clotting/haemostasis

Answer 1

Platelet count
Prothrombin time(PT)/ International Normalised Ratio
Activated partial thromboplastin time (APTT)
Fibrinogen test
D-dimer

Question 2

Uses of PT

Answer 2

Monitor patients on some medications e.g Warfarin

Diagnose clotting factors - VII,V,X,II,I

Question 3

Significance of prolonged PT

Answer 3

Deficiency in CF VII,V,X,II,I
Vit K deficiency
Liver disease
In patients with increased use of platelets - DIC/Sepsis

Question 4

Normal INR

Answer 4

0.8-1.2

In Warfarin patients 2-3

Question 5

Significance of elevated PTT

Answer 5

Use of anticoagulants
Haemophilia
Von willebrand disease
anti phospholipid antibodies
DI/sepsis

Question 6

aPTT normal time

Answer 6

25-40secs

Question 7

Conditions leading to high fibrinogen levels

Answer 7

Pregnancy
Inflammation
Infection incl. CRP

Question 8

Conditions leading to low fibrinogen levels

Answer 8

Liver failure

DIC

Question 9

Conditions leading to high D-dimer levels

Answer 9

Venous thromboembolism
Arterial clot
DIC
Severe sepsis
Malignancy
Liver disease
Surgery/trauma

Question 10

Groups of drugs

Answer 10

Anti coagulants - suppress coagulation pathway e.g Warfarin,Heparin, N/DOAC
Antiplatelets - inhibit platelet aggregation e.g. aspirin, clopidogrel
Thrombolytics - promote lysis of fibrin strand, dissolution of thrombi e.g Alteplase (t-PA)

Question 11

Warfarin

Answer 11

Vit K antagonists - VIII,VII

Question 12

Warfarin uses

Answer 12

Treatment and prevention of PE, DVT

Plrevent clots in AF, RHD, prosthetic heart valves

Question 13

Warfarin dosing

Answer 13

NTW
If rapid coagulation - 5-10mg for 2days, INR on day 3
AF - 1-2mg OD (3-4weeks to reach TW)
Maintenance - 3-9mg @same time each day

Pink - 5mg
Blue -3mg
Brown - 1mg
White -0.5mg

Question 14

Monitor Warfarin

Answer 14

Any therapy changes ; Starting/Stopping medication e.g Erythromycin >INR, Carbamazepine/phenytoin, St John’s wort, Oral contraceptives, Mineral supplements

Question 15

Side effects

Answer 15

Bleeding, Alopecia, vomiting, Rash, Skin necrosis, purple toes
Warfarin reversal - vit K. Fresh frozen plasma or prothrombin complex (octaplex)

Question 16

Heparin

Answer 16

also unfractionated Heparin
binds to antithrombin 3 - instantenous inactivation of thrombin
short action duration 4-6hrs

Contraindications - Haemophilia, Thrombocytopenia, peptic ulcers

Question 17

Diff in cofactors heparin and LMWH inhibit

Answer 17

Heparin - Xa and others

LMWH - Xa only

Question 18

Examples of N/DOAC and their MOA

Answer 18

Dabigatran(Pradaxa) - direct thrombin inhibitor
Apixaban (Xarelto), Rivaroxaban (Eliquis), Edoxaban (Lixiana) - direct Xa inhibitors

SE - Haemorrhage, Anaemia, Dizziness, Nausea

Question 19

Aspirin action

Answer 19

Good in arterial thrombosis

Inhibit prod of thromboxane A2 from arachidonic acid via inhibition of cyclo-oxgenase (COX) by acetylation

Question 20

Aspirin uses

Answer 20

Ischaemic Stroke, MI
secondary presentation of cardiovascular disease
Mild to moderate pyrexia

Question 21

Aspirin SE

Answer 21

gastrointestinal, haemorrhage, peptic ulcers

Question 22

Ticlopidine/Clopidogrel

Answer 22

ADP inhibit activity

Question 23

types of thrombolytics

Answer 23

Streptokinases - made from coccal - antibodies are formed by the body
Alteplase (tPA - tissue plasminogen activator)

Question 24

Uses of thrombolytics

Answer 24

PE, Arterial thromboembolism, acute MI

Contraindications - recent haemorrhage, trauma, surgery