Katzung 12th ed - Chapter 34 - Fibrinolytics (1)

Question 1

Streptokinase: dose for AMI or PE?

Answer 1

250,000 units IV over 30 mins, followed by an ongoing infusion of 100,000 units/hr for at least 24 hours.

Question 2

What is alteplase?

Answer 2

Alteplase is manufactured using the DNA for t-PA (it is recombinant t-PA)

Question 3

In basic terms, describe the pharmacodynamics of alteplase.

Answer 3

It specifically binds to fibrin, so it only acts at the site of the clot. Converts entrapped plasminogen to plasmin, which lyses fibrin.

Question 4

Alteplase: dose given?

Answer 4

60mg IV infusion in the first hour, then 20mg in the second hour, then 20mg in the third hour. Basically, 100mg is given over 3hrs, starting faster and then slowing down (some give the first 10mg within 1-2mins).

Question 5

Alteplase: half-life?

Answer 5

5 mins

Question 6

What is streptokinase, and what are its basic pharmacodynamics?

Answer 6

Streptokinase is a protein extracted from streptococci. It binds to plasminogen, triggering its conversion to plasmin, which lyses fibrin.

Question 7

What is urokinase, and what are its basic pharmacodynamics?

Answer 7

Urokinase is a human enzyme synthesized by the kidney. It is used as a fibrinolytic drug, because it directly converts plasminogen to plasmin, which lyses fibrin.

Question 8

What are the disadvantages of streptokinase?

Answer 8

If a patient has previously been exposed to streptokinase or streptococci, there may be fever, allergy, and/or therapeutic resistance upon administration of streptokinase. (But streptokinase is much cheaper than the other fibrinolytics)

Question 9

Urokinase: dose given?

Answer 9

Loading dose of 300,000 units given over 10 minutes. Followed by a maintenance infusion of 300,000 units / hr.

Question 10

What are the indications for using a fibrinolytic drug?

Answer 10

STEMI
PE with haemodynamic instability
Acute ischaemic stroke
Severe DVT