kidney and liver Flashcards
types of modified release
-Delayed (eg erythromycin capsules)
Enteric (colon-specific)
pulsatile
-Extended (eg. melatoin)
sustained release (release over sustained period of time but not constant, prolong time drug is in therapeutic range, oral)
controlled (release at constant rate, control drug concentration in the body, variety of dosage forms, release rate is more important than dose in therapeutic system)
Mechanism of controlled release
-diffusion
-osmotic
-dissolution
-responsive
Advantages and disadvantages of modified release
Advantages: maintain drug levels in therapeutic levels, better compliance, fewer administrations
Disadvantages: toxicity of polymer, undesirable bi-products of degradation, surgery to remove, high cost)
what are the types of gastroretention systems
-floating systems
-high density systems (not flashed out)
-mucoadhesive (attach to mucous membranes)
-expanding (can cause obstruction)
-magnetic (tumors)
how do loop diuretics work
-reduce K, Na, Cl reabsorption
-decrease reabsorption of magnesium and calcium
-used in heart failure and peripheral oedema
-vasodilators (left ventricular failure)
-acute renal failure to improve diuresis
eg. furosemide, bumetanide
how do osmotic agents work
-filtered through glomeruli but poorly reabsorbed
-increase osmolality of tubular fluid in PCT and LH
-prevent passive water reabsorption
s/e: hyperkalemia, hypernatremia, dehydration
eg. mannitol (used in cerebral oedema, reduce intraocular pressures before eye surgery)
how do thiazide diuretics work
-inhibit sodium and chloride reabsorption (hypokalemia, hyponatremia)
-increase Ca reabsorption indirectly
-inhibit Mg reabsorption indirectly
-reduce activity of Na/K ATPase pump
-can cause metabolic alkalosis (increased H loss)
eg chlortalidone, indapamide, bendromethiazide
how do potassium-sparing diuretics work
-aldosterone receptor antagonists (spironolactone, eplerenone)
prevent insertion of pumps and channels (ENaC)
used in hyperaldosteronism and oedema in liver failure
-Na channel blockers (amiloride, triamterene)
block apical ENaC in late DCT and CD
prevent excessive loss of K (loss of sodium and water, potassium retention)
