Pharmacology Flashcards
what do loop diuretics act on?
Na+/K+/2Cl- Co-transporter in the thick ascending loop of Henle
what do thiazide diuretics act on?
Na+/Cl- Co-transporter
in the distal tubule
Where is the site of action of potassium-sparing diuretics?
Block sodium potassium exchange in the distal tubule
what is the mechanism of loop diuretics?
What are the indications for loop diuretics?
to treat hypertension that is resisant to other anti-hypertensive drugs
pulmonary oedema
cardiac failure
renal failure
hypercalcamia
liver cirrhosis and ascites
what are the adverse affects of loop diuretics?
hypokalaemia
hypocalcaemia
hypomagnesiumaemia
hypovolaemia
Gout
metabloic alkalosis
what is the mechanism of action of thiazide diuretics?
what are the adverse affects of thiazide diuretics?
Hypokalaemia
Hypovolaemia
Hypomagnesiumaemia
Hypercalcaemia
Metabolic Acidosis
Gout
By what mechanism do diuretics increase K+ and H+ secretion?
What is the mechanism of action of potassium sparing diuretics?
Amiloride and Triamterene
Block the apical sodium channel decrease Na reabsorption
Spironolactone and Eplerenone
Compete with aldosterone for binding to intracellular receptors causing:
- decreased gene expression and reduced synthesis of a protein mediator that activates Na+ channels in the apical membrane (site 1)
- decreased numbers of Na+/K+ATPase pumps in the basolateral membrane (site 2)
indications for potassium sparing diuretics
Aldosterone antagonists are used in the treatment of:
Heart failure
Primary hyperaldosteronism (Conn’s syndrome)
Resistant essential hypertension
Secondary hyperaldosteronism (due to hepatic cirrhosis with ascites)
Thiazide and loop diuretics activate the renin-angiotensin-aldosterone system (in response to reduced blood pressure) Aldosterone antagonists potentiate the actions of thiazide and loop agents by blocking the effect of aldosterone
The major use of potassium sparing diuretics is in conjunction with other agents that cause potassium loss. Given alone, they cause hyperkalaemia
what is the indication and mechanism of action of osmotic diuretics?
(give an example)
used to prevent acute hypovolaemic renal failure to maintain urine flow.
They increase the osmolality of the filtrate, opposing the absorption of water in parts of the nephron that are freely permeable to water
Major site of action in the kidney is the proximal tubule where most iso-osmotic reabsorption of water occurs
Secondarily decrease sodium reabsorption in the proximal tubule (larger fluid volume decreases sodium concentration and electrochemical gradient for reabsorption)
mannitol i.v.
what are the two different types of diabetes insipidus?
Neurogenic diabetes insipidus – lack of vasopressin secretion from the posterior pituitary. Treated with desmopressin
Nephrogenic diabetes insipidus – inability of the nephron to respond to vasopressin
what is the mechanism of action and indication of vaptans/ aquaretics?
give an example
Act as competitive antagonists of vasopressin receptors
Tolvaptan is used in syndrome of inappropriate anti-diuretic hormone secretion (SIADH) to correct hyponatraemia
Name inhibitors of Sodium Glucose Co-transporter 2 (SGLT2)?
canagliflozin, dapagliflozin
