Thrombolytics and Diuretics Flashcards
Describe clot formation.
Injury to the vessel initiates the process. Platelets migrate to the area and adhere to the wall and each other. This creates platelet plug (thrombus). Thrombus has fibrinogen bound to it, which is acted on by thrombin to form fibrin. Fibrin forms long, fibrous threads that interlink throughout the clot to make a tough, strong clot.
Where does endogenous heparin originate?
Mast cells
What is heparin used for?
To prevent clot formation both in the body and when taking blood samples in tubes/syringes.
How does heparin work?
It inactivates thrombin (prevents conversion of fibrinogen to fibrin)
What is heparin-induced thrombocytopenia and what causes it?
A reduced number of platelets due to heparin use. Antibodies are created for heparin and bind to it, activating platelet aggregation around the heparin molecule and reducing the number of available platelets (increases risk of thrombotic event).
What are some contraindications of heparin?
pre-existing clotting disorder, active bleeding, recent intracranial or spinal surgery, acute liver damage, or severe hypertension.
What is protamine?
The antidote to heparin (binds to heparin and inactivates it)
What is the brand name for warfarin?
Coumadin
What is warfarin used for?
Rat poison, long term anti-coagulant. Mostly for thrombus prevention in chronic atrial fibrillation, cardiac valve replacement, and persistent embolic events.
How long does warfarin take to work and how long does it last?
24-72 hours and lasts 5-7 days
What is ASA and what is it used for?
Acetylsalicylic acid and is used for prophylaxis of clots, generally in elderly populations to reduce MI and stroke risk.
What is the only current thrombolytic (clot buster)
tPA (tissue plasminogen activator) aka Altepase
How does tPA work?
It activates plasminogen which converts to plasmin when bound to the clot. Plasmin breaks the fibrin threads apart and dissolves the clot.
What is Altepase used for?
MI, decompensating PE, and ischemic stroke.
When should tPA be given and why?
<3-4.5 hours to reduce the risk of ischemic injury.
What is furosemide?
Lasix (loop diuretic)
How does Lasix work?
Decreases reabsorption of NaCl in loop of Henle (so more salt and therefore water is peed out)
What are some concerning side effects of loop diuretics?
Loss of K+ and H+ causing electrolyte imbalances and cardiac dysrhythmias, and hypokalemia causing metabolic alkalosis.
What is Acetazolamide?
A carbonic anhydrase inhibitor (diuretic).
How does acetazolamide work?
It is a carbonic anhydrase inhibitor so it works in the proximal tubule. Carbonic anhydrase catalyzes the conversion of CO2 into bicarb and hydrogen ion. Blocking this means less bicarb is reabsorbed, so patients develop metabolic acidosis. Generally used in response to metabolic alkalosis caused by lasix.
What are alternative uses for acetazolamide?
For glaucoma, altitude sickness, and epileptic seizures.
What is spironolactone?
A potassium-sparing diuretic.
How does spironolactone work?
It is a competitive aldosterone antagonist so it decreases water and Na+ reabsorption and increases K+ reabsorption.
What is spironolactone often used for?
Hypertension, heart failure, and to balance metabolic acidosis caused by Lasix.
