diuretics Flashcards
Thiazides
- hydrochlorothiazide, chlorthalidone, indapamide
indicated for HTN, oedema, nephrogenic diabetes insipidus, contain sulfonamide
mechanism: moderately potent diuretic
- inhibit Na/Cl receptors in proximal DCT, prevent reabsorption of Na+ CL, produce a increase K excretion
SE:
CI in severe renal impairment/ anuria
Gout - diuretic-induced rise in serum uric acid concentration may precipitate gout (increase risk if high dose)
use low dose like 25mg then high, as high has more metabolic adverse effect
SE: dizzy, weak, muscle cramp, hypotension, hypontreamia, hypokalaemia, hypomg, dyslipidaemia, jaundice (nothing common)
Amiloride
it is a potassium sparing diuretic (weak), inhibit Na channel in distal tubule reduce urinary K excretion
SE:
hyperkalaemia, hyponatremia*
CI:
in renal failure, as renal impairment increase risk of hyperkalaemia,
spironolactone
mechanism: aldosterone antagonist inhibit Na absorption in distal tubule reduce K excretion
indication”: improves outcome in HF, use with ACEI, loop diuretic, digoxin in severe HF, monitor K every week then months
SE:
hyperkalaemia, hyponatraemia, gynaecomastia, menstrual irregularities
CI in renal failure, avoid in severe impairment (increase risk of hyperkalamia),
Pt with cirrhosis, spironolactone may precipitate if metabolic derangement occurs: renal failure, hyperchloraemic metabolic acidosis (associated with hyperkalaemia), hepatic encephalopathy
acetazolamide (diamox)
indicated for glaucoma, seizures, benign intracranial HTN, altitude sickeness, diuretics
Mechanism: carbonic anhydrase inhibitor forces kidney to excrete HCO3, cause H and Cl retention act on proximal tubule
SE: metabolic acidosis, parasthesia, taste alteration, phosphate kidney stone
CI in pregnancy, SCA (sickle cell anaemia?), liver/ renal disease
ADH - antagonist
- demeclocycline
antagonises the effect of antidiuretic hormone on renal tubules, promote excretion of free water, use in SIADH (sydrome of inappropriate antidiuretic hormone secretion) resistant to fliud restirction and high salt intake
Frusemide - lasix
Loop Diuretics, contain sulfonamide
Indication: oedema* for HF, hepatic cirrhosis, renal impairment and nephrotic syndrome/ severe hypercalcaemia
CI in pregnancy (category C - cause fetal electrolyte disturbances, neonatal thrombocytopenia)
Mechanism:
inhibit reabsorption of Naand Cl in ascending limb of loop of Henle, works on Na/K/Cl exchange (20% of filtered Na potent, rapid, intense diuresis)
SE:
hyponatremia, hypokalaemia, hypomagnesaemia, dehydration, hyperuricaemia, gout, hypocalcaemia, deafness(espcially with rapid IV administration) more common, may impair renal function (if tx with nephrotoxic drugs increase risk of nephrotoxcity)
Use in combination with ACEI in HF,monitor fluid status, electrolyes