Lipid Lowering & Antithrombotic Drugs

Question 1

Heparin

Answer 1

• naturally occuring mucopolysaccharide that occurs in a vairety of sizes
• High negative charge
• Unfractionated so many MWs
• Low MW are clinical
• Adminsted by injection as its absorbed by the gut

Question 2

Action of Heparin

Answer 2

• inhibits thrombin, factor X and factor IX but thrombin is most sensitive.
• Requires presence of antithrombin III and a endogenous protease inhibitor
• Normally ATIII opposes coagulation
• also complexes with Factors IX and X
• heparin needs to bind both ATIII and Factor IIa (thombin)
• Increases ATIII/Xa complexes
• Low MW are shorter and only effect Xa

Question 3

problems with heparin

Answer 3

Needs injection
can cause haemorrrhaging
in severe cases use positive drug protoamine to complex with heparin.

Question 4

Warfarin

Answer 4

Orally taken

• antagonist to vitamin K
• prevents prothrombin -> thrombin
• affects factors II, VII, IX and X
• prevents Y carboxylation of precursors therefore inactive in causing coagulation
• competitivly binds to vitamin K reductase

Question 5

problems with warfarin

Answer 5

• slow onset
• vitamin K levels can change in the diet making competition
• exists in R/S isomers so can be different activities
• risk of haemorrhaging - give VK if its bad
• can cause birth defects
• Interactions with other drugs

Question 6

Aspirin

Answer 6

• Antiplatelet drug
• irreversably binds COX1 enzyme, reducing TxA2 synthesis
• low doeses dont reduce endothelium levels (cells with nucleus)

Question 7

Ticagrelor

Answer 7

allosterically inhibts ADP receptor (heart attack)

Question 8

clopidogrel

Answer 8

inhibits glycoprotein IIb/IIIa receptor expression on platelets by blocking ADP receptors irreversably

Question 9

epoprostenol

Answer 9

• adds to PGI2 activity
• Raises intraccelualr cAMP levels
• short half life (needs injection)
• powerful vasodilator