Clotting and Anticoagulation - AC/AP

Question 1

Primary haemostasis

-steps after the vessel is injured

Answer 1

Vessel wall damage => reflex VC

• endothelium constantly produces PC => prevents platelets activatiion
• PC release interrupted when damaged

Collagen + vWF revealed to platelets => adhere and activated => aggregation (ADP), VC (seretonin, thromboxane)
Form plug via fibrinogen receptors activated by ADP

Question 2

Antiplatelet drug target sites

-examples

Answer 2

Aspirin

• COX1 inh => inh thromboxane formation
• COX2 inh => inh inflammatory, analgesia at higher doses

Clopidogrel, prasugrel, ticagrelor
P2Y12 => inh ADP, prevent aggregation

Specialist use
GP2b3a => inh fibrinogen rec action, stops aggregation

Question 3

Secondary hemostasis

• extrinsic pathway = outside vessels
• instrinsic pathway

Answer 3

Blood, factors leaks out of vessels
TF found on damaged cells
-TF + 7 => 10 => 2 thrombin => 1 via activated platelet

Thrombin triggers intrinsic and activates more platelets
12 => 11 => 9 => 8 => 5 => 10 => 2 => 1

APC => degrades 5, 8

Question 4

Breakdown of clots

Answer 4

Plasminogen =(tPA-fibrin)=> plasmin => clot breaks down

Question 5

Anticoagulant drug target sites

Answer 5

Heparin (IV) - antithrombin activator => inactivates Xa, thrombin

Fondaparinux - like heparin

Warfarin - 1(0)972 production slowed

DOAC - inh Xa
Dabigatran - inh thrombin

Question 6

Fibrinolytics
-drug target sites

Antifibrinolytics
-drug target sites

Answer 6

Lyse arterial thrombus
Streptokinase - binds, activates plasminogen
Alteplase - binds to fibrin+plasminogen

Tranexemic acid - inh plasminogen

Question 7

Differences between clopidogrel, prasugrel, ticagrelor

Answer 7

Clopidogrel

• irreversible prodrug
• lowest bleeding risk

Prasugrel

• irreversible prodrug
• highest bleeding risk

Ticagrelor

• reversible active
• mid bleeding risk

Question 8

Warfarin counselling

• MOA
• CI
• taking warfarin and monitoring
• duration
• SE
• lifestyle

Answer 8

Warfarin is a medication that reduces the stickiness of the blood, reducing the likelihood of clots forming

CI

• liver, kidney problems
• increased bleed risk

Taking warfarin

• slowly build up dose => stable INR reached
• frequent monitoring => less frequent as INR stabilizes => every 3 months
• take warfarin at same time everyday

Duration
PE, DVT => 3/6months
AF, mech valve => forever

SE

• may bleed/bruise more easily
• prolonged bleeds, hematuria, melena, hemoptysis => A&E

Lifestyle

• careful when shaving
• avoid NSAIDs, aspirin
• avoid large amounts of VitK

Question 9

DOACs

• MOA
• CI
• taking DOACs and monitoring
• duration
• SE
• lifestyle

Answer 9

MOA - helps thin blood, making it less likely for clots to form
-reduces the chance that you develop DVT/PE again/a stroke

Monitoring
Before, annually - renal function (renal excretion)

PO OD/BD with water upright at same time
-forgotten dose => take it as soon as you remember, no double dosing

Duration

• 3/6months DVT PE
• life AF

SE - easy bleeding esp in first few weeks
Go to A&E if
-hematuria/melena
-nosebleeds that don’t stop/persistent bleeds
-hematemesis
-headache, seizures, visual changes, tingling/weak limbs
-anaphylaxis

Lifestyle

• careful when shaving
• avoid NSAIDs, aspirin

Question 10

Single AP therapy
DAPT
Triple therapy

Answer 10

AP CI

• active bleed
• GI ulcer

DAPT - 2 AP (give ranitidine/pantoprazole)
Triple - 2 AP + 1 AC (if indications for both AC and AP use)