end Flashcards
Phenylalkylamine
Verapamil
Benzothiazepine
Diltiazem
1,4-Dihydropyridines
Nifedipine (prototype) Amlodipine (longest acting)
Use-dependent CCBs
Verapamil Diltiazem
Voltage-dependent CCBs
Nifedipine Amlodipine
What CCB do you use for Angina?
Diltiazem Because decreases SA node firing rate, reduces cardiac after load by vasodilation, also increases blood flow to myocardium to prevent ischemia Nifednipine and Amlodipine can also be used because they reduce myocardial oxygen demand and arterial pressure
What CCBs are used for Supraventricular arrhythmias?
Diltiazem or Verapamil Because they reduce the firing rate of the SA node and reduce conduction through AV node
Which CCBs are used to treat hypertension?
Usually Dihydropyridines Because of potent vasodilator effects BUT may trigger reflex tachycardia particularly with short acting Dihydropyridines
Diuretics, Vasodilators
Fenoldopam, Dopamine, Atriopeptins
What is the mechanism of action of the vasodilatory diuretics??
Increase RBF without decreasing GFR FF decreases (reduces protein conc and hydroosmotic forces in peritubular capillaries)– allow Na and H20 to leak back into the tubule This reduces net reabsorption so Na excretion increases Weak as diuretics due to compensatory Na reabsorption in more distal nephron segment
Osmotic diuretic Freely filterable at glomerulus Not reabsorbed Metabolically inert
Mannitol
What is the mechanism of action of osmotic diuretics??
Given intravenously Act in tubular lumen as non-reabsorbable solute Urine volume and sodium excretion are proportional to the osmotic load Increases the urinary excretion of sodium, potassium, chloride, water and mannitol
What are osmotic diuretics used for?
Edema Glaucoma-reduces intraocular pressure Acute renal failure
Carbonic Anhydrase Inhibitor Orally active Weak diuretics Inhibited by acidosis-limits clinical use
Acetazolamide
What is the mechanism of carbonic anhydrase inhibitors?
Filtered and secreted by the organic acid transporter (OAT) - acts from tubular lumen Inhibit carbonic anhydrase in the proximal and distal tubule Carbonic anhydrase provides hydrogen ions for bicarbonate reabsorption Increase the excretion of sodium, potassium, bicarbonate and water Alkalinize the urine
What are Carbonic Anhydrase inhibitors used for?
Glaucoma - reduced aqueous humor formation and intraocular pressure Alkalinize the urine – decrease drug toxicity Mountain or altitude sickness Anticonvulsant SE= Metabolic acidosis, hypokalemia
Loop Diuretics Rapid onset, short duration of action
Furosemide, Bumetanide, Ethacrynic Acid
What is the mechanism of Loop Diuretics??
Filtered and secreted by the OAT Inhibits Na-K-2Cl symporter Acts on cortical and medullary segments of the ascending limb of the loop of Henle Increase excretion of Na, K, Cl and H20
What are the Loop Diuretics used for?
Edema of cardiac, hepatic or renal origin Acute pulmonary edema HTN
Thiazide and Thiazide-Like Diuretics Moderate onset of activity Long duration of action
Hydrochlorothiazide Metolazone
What is the mechanism of action of Thiazide diuretics?
Filtered and secreted by the OAT Inhibits Na-Cl symporter Acts on cortical segment of distal tubule Increases excretion of Na, K, Cl and H20 Urine is hypertonic - unable to dilute
What are the Thiazide Diuretics used for?
Edema due to CHF HTN Hypercalemia/Ca salt-renal caliculi
K+ Sparring Diuretics, Aldosterone Antagonists
Spironolactone, Eplerenone
