Anticoagulants, atherosclerosis and hyperlipidaemia drugs Flashcards
Heparin:
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.
Warfarin:
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.
Aspirin:
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).
Statins:
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.
Ezetimibe:
inhibits a specific cholesterol transporter in gut, inhibiting intestinal cholesterol absorption.
Colestyramine:
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.
Fibrates:
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.
What is an Embolus?
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
Enoxoparin
low molecular weight heparin, does not bind to thrombin but does increase the affinity of antithrombin iii for factor Xa
Factor Xa
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
Prostacyclin
aka prostaglandin 12
naturally occuring inhibitor of platelet aggregation
plays an important role in regulating coagulation
produced by epithelial cells lining inttact blood vessels
Streptokinase
clot busting drug- activator of plaminogen.
can restore blood supply if given in a short time after stroke or myocardial infarction
Reteplase
clot busting drug-activator of plaminogen.
can restore blood supply if given in a short time after stroke or myocardial infarction
Epoprostenol
synthetic version of prostacyclin
mimics the anticoagulant actions of prostacyclin
very short plasma half life
causes flushing, headache and hypotension
Clopidogrel
irreversible antagonist at ADP receptors
inhibitor of platelet aggregation
used to prevent thrombosis
What is a platelet?
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
Dipyramidole
phosphodiesterase inhibitor. Prevents breakdown of cAMP in platelets, reducing their aggregation. Sometimes used in addition to aspirin.
What is a stroke?
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
What is a thrombus?
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
What is thrombin?
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
What is antithrombin?
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
Alteplase
A clot busting drug
an activator of plasminogen
Simvastatin
statin
used to treat high cholesterol levels
targets HMG-CoA reductase
Fish oils
used to lower plasma lipids but raises chlesterol levels
Fenofibrate
fibrate drug,used to lower cholesterol. acts (probably) at a nuclear hormone receptor called PPAR alpha
Nicotinic Acin
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
Bezafibrate
used to lower cholesterol
acts at a nuclear hormone receptor called PPAR alpha
Atovastatin
a statin
used to treat high cholesterol
targets HMG-CoA reductase
