Thrombolytics

Question 1

What are the 2 main mechanisms of action of fibrinolytic drugs and give examples

Answer 1

Generate plasmin themselves (e.g. r-tPAs - alteplase)
Work preferentially in presence of fibrin
Non-immunogenic
Can be given repeatedly and easier to administer, but expensive

Binding to/activating endogenous plasminogen (e.g. Streptokinase)
Causes degree of fibrinolytic activity in general circulation
Derived from bacterial product so produces immune response

Question 2

What are the indications for fibrinolytic use

Answer 2

Acute MI
Major PE
Acute ischaemic stroke

Question 3

What are the main ADRs of fibrinolytic drugs

Answer 3

Increased risk haemorrhage (stroke, GI)

Allergic response, transient hypotension (streptokinase)

Question 4

What are the contraindications for using using fibrinolytics

Answer 4

History heaemorrhagic stroke
Active peptic ulcer
Other bleeding source
Recent trauma/surgery
CNS neoplasm
Aortic dissection
Uncontrolled hypertension
Known bleeding disorder

Question 5

How are thrombi normally cleared

Answer 5

Plasmin:
Cleaves fibrin to degradation products
Acts on coagulation factors II, V, VII