Session 9 - Diuretics Flashcards
What are the four functions of the renal system?
REEM Regulatory Excretory Endocrine Metabolism
How is the renal system regulatory?
Fluid balance
Acid-base balance
Electrolyte balance
What excretory functions does the renal system have?
Waste products
Drug Elimination – Glomerular filtration and Tubular secretion
What endocrine functions does the renal system have?
Renin-Angiotensin-Aldosterone System
Erythropoetin
Prostaglandins
What does the renal system do in metabolism?
Vitamin D
Polypeptides – Insulin and PTH
Give 7 drugs that work on the renal tubules
o Carbonic Anhydrase Inhibitors o Osmotic Diuretics o Loop Diuretics o Thiazide Diuretics o Potassium Sparing Diuretics o Aldosterone Antagonists o ADH Antagonists
What do carbonic anhydrases do?
o Given systemically it interferes with Na+ and HCO¬¬3- reabsorption, giving it a weak diuretic effect. Danger of metabolic acidosis.
When are carbonic anhydrases used?
Glaucoma
Name an osmotic diuretic and when it would be used
Mannitol
Raised ICP
What is the mech of action of an OSMOTIC DIURETIC
Freely filtered at the glomerulus, but only partially, if at all, reabsorbed
Passive water reabsorption is reduced by the presence of this non-reabsorbable solute within the tubule lumen
What are two contraindicative conditions for osmotic diuretics?
Congestive heart failure
Pulmonary oedema
What is the site of action of osmotic diuretics?
Tubular segments that are water permeable
Proximal tubule, descending loop of Henle, collecting ducts
Give an adverse drug reaction of osmotic diuretic
Chills and fever
Why are osmotic diuretics not used in heart failure?
Because expansion of blood volume may be greater than degree of diuresis
Give two examples of thiazide diuretics
Bendroflumethiazide
Metolazone
Give an indication for thiazide diuretics?
Hypertension
Oedema secondary to congestive cardiac failure, liver disease or nephrotic syndrome
What is the mech of action of thiazide diuretics?
Thiazide diuretics inhibit the Na+/Cl- co-transporter in the luminal membrane in the distal tubule of the kidney. This blocks the reabsorption of Na+ and therefore water. Result is lower blood volume and pressure.
Give a couple of adverse drug reactions (and thus contra-indications) of thiazide diuretics - think minerallss
Hypokalaemia, hyperuricaemia, impaired glucose tolerance, Hyponatraemia, hypermagnesemia, Hypercalcaemia, metabolic alkalosis
What four drugs should thiazide not be used with?
Steroids – Increased risk of hypokalaemia
Beta-Blockers – Hyperglycaemia, Hyperlipidaemia, Hyperuricaemia
Digoxin – Hypokalaemia increases digoxin binding and toxicity
Carbamazepine – Increased risk of Hyponatraemia
Give an example of a loop diuretic
Furosemide
Bumetanide
Torasemide