Manipulating kidney function Flashcards
main kidney functions
Excretion of nitrogenous waste products and xenobiotics
Regulation of water, electrolyte, mineral and acid-base balance
Production or activation of hormones (calcitriol – active
vitamin D3; erythropoietin)
diuretic mechanism of action
direct action on the nephron
Inhibit sodium chloride reabsorption to incr salt and water excretion
Counter-act salt and water retention in heart failure
Activate renin secretion
loop diuretics
Act on ascending Loop of Henle from tubule side
Heavily plasma protein bound – reach site of action by PCT secretion
most efficacious of the clinically available diuretics
pulmonary venodilator action when given intravenously
thiazide diuretics
Act on the early distal tubule (DCT)
Bind to the Cl- site of the Na+/Cl- co-transporter
Less efficacious than loop diuretics
anti-hypertensive effects include vascular action
thiazide diuretics - drugs
Chlorothiazide and hydrochlorthiazide
loop diuretics - drug
Furosemide
Potassium sparing diuretics
Act on the collecting tubule to inhibit the action of aldosterone
used to prevent potassium loss
Potential adverse effect – hyperkalaemia
Potassium sparing diuretics - Spironolactone
competitive antagonist of aldosterone
hyperkalaemia is less of a risk
can help in heart disease
Potassium sparing diuretics - Triamterene and amiloride
non-competitive inhibitors of aldosterone
General adverse effects of diuretics
Hypokalaemia - Furosemide
Hypomagnesaemia - Thiazides
Hyperkalaemia - K+ sparing diuretics
Hyponatraemia - All diuretics – poor prognosis
Hypochloraemic metabolic alkalosis - Furosemide and thiazides
drug interactions
Diuretics are synergistic with vasodilator drugs
Reduce the dose once congestion resolves
Renal prostaglandins are natriuretic (salt losing)
NSAIDs exacerbate salt and water retention in heart failure, reducing efficacy of diuretics + COX-1 and COX-2 inhibition
