Anticoagulants, atherosclerosis and hyperlipidaemia drugs

Question 1

Heparin:

Answer 1

inhibits the actions of thrombin, factor X and factor IX, which are needed in the clotting cascade. Therefore, fibrinogen cannot be converted to fibrin and a clot cannot form. Also increases the strength of binding of ATIII (thrombin inhibitor) to thrombin and Factor Xa. Molecule carries a high negative charge. Given by injection. Risk of haemorrhage.

Question 2

Warfarin:

Answer 2

related in structure to Vitamin K. Acts by competitively inhibiting an enzyme involved in the recycling of Vitamin K (vitamin K reductase), which is needed for the formation of various clotting factors.

Question 3

Aspirin:

Answer 3

antiplatelet drug. Irreversibly inhibits platelet COX enzyme, reducing TxA2 synthesis. TxA2 is a major stimulant for platelet aggregation. Platelets have no nuclei so cannot synthesise new enzyme so aggregation is reduced until new platelets are made (7-10 days).

Question 4

Statins:

Answer 4

competitively inhibit HMG-CoA reductase (rate limiting enzyme in production of cholesterol), thereby lowering the liver’s production of cholesterol. Lowered cholesterol leads to more LDL receptors and so, increased removal of LDL (bad cholesterol) from plasma.

Question 5

Ezetimibe:

Answer 5

inhibits a specific cholesterol transporter in gut, inhibiting intestinal cholesterol absorption.

Question 6

Colestyramine:

Answer 6

anion exchange resin. Binds to bile acids and stops them from being reabsorbed. Leads to increased conversion of newly synthesised cholesterol into bile acids and increased uptake of LDL by the liver.

Question 7

Fibrates:

Answer 7

agonists at a nuclear hormone receptor called PPAR alpha and seem to alter transcription of some of the genes involved in lipid metabolism. Their overall effect though is to reduce plasma LDL. Also reduce fibrinogen. Mechanism not well known.

Question 8

What is an Embolus?

Answer 8

blood clot that has become detached from the vessel wall and is travelling through the blood.
may lodge in a small vessel, block it and cut off the blood supply to tissue

Question 9

Enoxoparin

Answer 9

low molecular weight heparin, does not bind to thrombin but does increase the affinity of antithrombin iii for factor Xa

Question 10

Factor Xa

Answer 10

enzyme in clotting cascade
produced from inactive factor X by the actions of factor ixa, converts prothrombin–> thrombin.
target of heparin and low molecular weight heparin

Question 11

Prostacyclin

Answer 11

aka prostaglandin 12
naturally occuring inhibitor of platelet aggregation
plays an important role in regulating coagulation
produced by epithelial cells lining inttact blood vessels

Question 12

Streptokinase

Answer 12

clot busting drug- activator of plaminogen.

can restore blood supply if given in a short time after stroke or myocardial infarction

Question 13

Reteplase

Answer 13

clot busting drug-activator of plaminogen.

can restore blood supply if given in a short time after stroke or myocardial infarction

Question 14

Epoprostenol

Answer 14

synthetic version of prostacyclin
mimics the anticoagulant actions of prostacyclin
very short plasma half life
causes flushing, headache and hypotension

Question 15

Clopidogrel

Answer 15

irreversible antagonist at ADP receptors
inhibitor of platelet aggregation
used to prevent thrombosis

Question 16

What is a platelet?

Answer 16

Small, disc like cell fragments
important in blood clotting
can be activated and release signals that activate other platelets and cause them to aggregate together.
do not have a nucleus so cannot synthesise proteins

Question 17

Dipyramidole

Answer 17

phosphodiesterase inhibitor. Prevents breakdown of cAMP in platelets, reducing their aggregation. Sometimes used in addition to aspirin.

Question 18

What is a stroke?

Answer 18

a blockage of a blood vessel resulting in a lack of oxygen supply to part of the brain, and damage or death of thate tissue

Question 19

What is a thrombus?

Answer 19

a pathological blood clot that forms in a blood vessel in the absence of a breach in the vessel.
may be caused by damage to vessel wall, by altered blood flow, or by increases in the coagulability of the blood

Question 20

What is thrombin?

Answer 20

an enzyme in the clotting cascade
converts fibrinogen to insoluble fibrin 
a target of heparin 
also known as factor IIa
is produced by factor II (prothrombin) by enzyme factor Xa

Question 21

What is antithrombin?

Answer 21

A natuarlly occuring inhibitor of thrombin and factor Xa. Binds to them to form an inactive complex. Hearin binds to ATII, increasing its affinity for thrombin and factor Xa

Question 22

Alteplase

Answer 22

A clot busting drug

an activator of plasminogen

Question 23

Simvastatin

Answer 23

statin
used to treat high cholesterol levels
targets HMG-CoA reductase

Question 24

Fish oils

Answer 24

used to lower plasma lipids but raises chlesterol levels

Question 25

Fenofibrate

Answer 25

fibrate drug,used to lower cholesterol. acts (probably) at a nuclear hormone receptor called PPAR alpha

Question 26

Nicotinic Acin

Answer 26

vitamin niacin
used to lower cholesterol levels
unclear mechanism
higher doses needed that for its action as vitamin
causes vasodilation, impaired glucose tolerance and gout

Question 27

Bezafibrate

Answer 27

used to lower cholesterol

acts at a nuclear hormone receptor called PPAR alpha

Question 28

Atovastatin

Answer 28

a statin
used to treat high cholesterol
targets HMG-CoA reductase