17.diuretics
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Transcript of 17.diuretics
Classification
1. High efficacy diuretics (Inhibitors of Na+-K+- 2Cl- cotransport)
e.g. Furosemide , bumetanide , ethacrynic acid
2. Medium efficacy diuretics ( Inhibitors of Na+- Cl- symport) e.g. Chlorothiazide, benzthiazide , indapamide, chlorthalidone
Classification (contd..)
3. Weak or adjunctive diuretics
a) Carbonic anhydrase inhibitors :Acetazolamide
b) Potassium sparing diuretics :
Spironolactone, triamterene , amiloride
c) Osmotic diuretics : Mannitol, glycerol
HIGH-EFFICACY (LOOP) DIURETICS
Site of action – thick ascending limb of
Loop of Henle
•Inhibit the luminal Na+-K+-2Cl-
transporter - reduce reabsorption of
NaCl •Prevent reabsorption of Ca2+ and Mg2+
Therapeutic uses of loop diureticsAcute pulmonary edema – i.v. furosemide
Renal edemaHypertension associated with renal failure
& congestive heart failure
Hypercalcemia & renal calcium stones
Hyperkalemia
Forced diuresis – in cases of poisoning
• Medium efficacy diuretics
• Site of action – distal convoluted tubule
Block Na+/ Cl- transporter – inhibit NaCl reabsorption
Increase Ca2+ reabsorption
THIAZIDE DIURETICS
Hypokalemia Hyponatremia Hyperuricemia - attacks of gout Hyperglycemia Hyperlipidemia Hypocalcemia – loop diuretics; hypercalcemia – thiazides Ototoxicity – esp. ethacrynic acid GIT disturbances Allergic reactions
Adverse effects of high ceiling &
thiazide diuretics
III. Carbonic anhydrase inhibitors Acetazolamide, dorzolamide Site of action – Proximal convoluted tubule Inhibits carbonic anhydrase activity -
decreases HCO3- reabsorption - alkaline
diuresis
Therapeutic Uses
• Glaucoma: acetazolamide, dorzolamide
• Urinary alkalinization : UTI ; to promote
excretion of certain acidic drugs
• Metabolic alkalosis
• Acute mountain sickness
Adverse effects
• Acidosis
• Renal stones
• Hypokalemia
• Drowsiness , fatigue
• Hypersensitivity reactions
POTASSIUM SPARING DIURETICS• Site of action - Late distal tubule & collecting duct
Spironolactone – aldosterone antagonist
Competitively inhibit the binding of
aldosterone to mineralocorticoid receptor
inhibits formation of aldosterone-induced
proteins (AIPs) – prevent sodium
reabsorption and potassium excretion
Therapeutic uses: Hyperaldosteronism (cardiac failure, liver and
kidney disease, Conn syndrome)
Hypertension (with thiazide /loop diuretics)
Adverse effects: Hyperkalemia Drowsiness, confusion Abdominal upset Impotence Menstrual irregularities
OSMOTIC DIURETICS
• Mannitol Freely filtered at the glomerulus Not reabsorbed at the renal tubulesRelatively inert pharmacologicallyNon - metabolizable Increases plasma osmolarity
• Decrease sodium reabsorption• Dilute tubular fluid and increase water
excretion
USES:
1.Head injury or stroke
2.Glaucoma
3. In cases of poisoning
3.To maintain g.f.r. and urine flow in patients with impaired renal function
A/E: Headache, nausea, vomiting
Excessive plasma volume expansion –
pulmonary edema