Anticoagulants

Question 1

What medications are used to treat myocardial infarction? (emergency)

Answer 1

Emergency: 
Primary survey + MAG 
- Morphine, for analgesia and vasodilation 
- Aspirin + clopidogrel 
- GTN for NO and vasodilation 

Oxygen supply if SpO2 drops

Question 2

What is treatment rationale for myocardial infarction? (short term for STEMI and NSTEMI)

Answer 2

STEMI:

• Percutaneous intervention to place bare metal stent
• Fibrinolysis (t-PA; alteplase)
• Adjuvant UFH

NSTEMI:

• No thrombolysis due to risk of rupturing the fibrous cap
• LMWH or UFH
• Antiplatelet agents

Question 3

List medications, class and mechanism of action used for treating MI

Answer 3

GTN (nitroglycerin):
Prodrug which is activated to become NO, and leading to vasodilation, reducing preload and afterload, and increasing myocardial blood supply.

Morphine:
Binds to mu opioid receptors to produce analgesic effect and decreases systemic sympathetic response (lower HR, low BP, decrease myocardial oxygen demand)

Aspirin:
Antiplatelet, non-selective COX inhibitor, and through COX1 inhibition, thromboxane A2 inhibitor, leading to lack of platelet aggregation.

Clopidogrel:
Antiplatelet, binds and inhibits P2Y12 and ADP, preventing platelet aggregation.

Question 4

What’s alteplase and mechanism of action, side effects and contraindications?

Answer 4

Alteplase is a tissue plasminogen activator. Plasminogen binds to fibrin, then it becomes plasmin and causes fibrinolysis.

Side effects: increased risk of bleeding, hypotension and dizziness.

Contraindicated in those with active bleeding, aortic dissection, prior intracranial haemorrhage.

Question 5

What is the side effect of Nitroglycerin?

Answer 5

Hypotension (treat with atropine)
Headache
Bradycardia

Question 6

What are side effects and contraindications of morphine?

Answer 6

Side effects:

• Constipation
• Respiratory distress
• Nausea & vomiting
• Dependence
• Sedation

Contraindications:

• Opioid dependence
• Opioid treatment

Question 7

What are side effects and contraindications of aspirin?

Answer 7

Side effects:

• Increased risk of bleeding
• Asthma attack
• GIT discomfort, erosions, ulcers (due to loss of mucosal protective layer by prostaglandin)
• Renal damage

Contraindications:

• Asthma
• Active bleeding
• Bleeding disorder, or GIT bleed

Question 8

What’s long term management of MI?

Answer 8

• SAAB therapy and anticoagulant to prevent mural thrombus.
• Statins (HMG CoA reductase inhibitor, preventing liver synthesis of cholesterol and increase uptake from circulation, decrease lipid content added to plaque)
• Aspirin
• ACEI (decrease vasoconstriction, decrease BP, and decrease pressure on heart)
• Beta-blockers to reduce inotropic and chronotropic effects on the heart –> decrease O2 demand and decrease BP

Question 9

What anticoagulant long term therapy will you use?

Answer 9

Warfarin and bridging therapy with UFH or LMWH for at least 5 days, with INR between 2-3 on consecutive two readings.

Question 10

How do you monitor warfarin?

Answer 10

INR (therapeutic range between 2-3)

Question 11

How do you monitor UFH?

Answer 11

aPTT (between 60-90 seconds)

Needs to be done every 6 hours

Question 12

What are some complications of heparin therapy?

Answer 12

• Heparin induced thrombocytopenia and thrombosis (HITT): antibody develops against heparin when it is bound to platelet growth factor 4. They form a complex with heparin in the bloodstream and leads to formation of blood clots, reducing serum platelet count.
• Haemorrhage
• Osteoporosis (chronic heparin use decreases BMD)
• Allergy
• Alopecia