CV: Diuretics Flashcards
In general, thiazides are used for what?
To relieve oedema due to chronic heart failure and, in lower doses, to reduce blood pressure.
In general, loop diuretics are used in what?
In pulmonary oedema due to left ventricular failure and in patients with chronic heart failure.
Thiazides and related compounds are moderately potent diuretics, how do they work?
They inhibit sodium reabsorption at the beginning of the distal convoluted tubule.
How rapid is the onset of action of thiazide and related compounds?
Thiazides and related compounds are moderately potent diuretics; they inhibit sodium reabsorption at the beginning of the distal convoluted tubule. They act within 1 to 2 hours of oral administration and most have a duration of action of 12 to 24 hours; they are usually administered early in the day so that the diuresis does not interfere with sleep.
Thiazide and related compounds have a duration of action of what?
Thiazides and related compounds are moderately potent diuretics; they inhibit sodium reabsorption at the beginning of the distal convoluted tubule. They act within 1 to 2 hours of oral administration and most have a duration of action of 12 to 24 hours; they are usually administered early in the day so that the diuresis does not interfere with sleep.
In the management of hypertension, what dose of thiazide produces a maximal or near-maximal response?
In the management of hypertension a low dose of a thiazide produces a maximal or near-maximal blood pressure lowering effect, with very little biochemical disturbance. Higher doses cause more marked changes in plasma potassium, sodium, uric acid, glucose, and lipids, with little advantage in blood pressure control.
What are the preffered thiazide diuretics in the management of hypertension?
Chlortalidone and indapamide are the preferred diuretics in the management of hypertension. Thiazides also have a role in chronic heart failure.
Bendroflumethiazide is licensed or the treatment of hypertension but is no longer considered first-line diuretic for this indication. What else can it be used in?
Mild to moderate heart failure.
Those who have a stable blood pressure on bendro therapy should continue on it.
Chlortalidone is a thiazide-related compound with what duration of action?
Chlortalidone, a thiazide-related compound, has a longer duration of action than the thiazides and may be given on alternate days to control oedema
How does the longer duration of action of chlortalidone vs thiazides impact its use in therapy?
Chlortalidone, a thiazide-related compound, has a longer duration of action than the thiazides and may be given on alternate days to control oedema
Xipamide and indapamide are chemically related to the thiazide-like chlortalidone.
Why is does indapamide see wider clinical use?
Xipamide and indapamide are chemically related to chlortalidone. Indapamide is claimed to lower blood pressure with less metabolic disturbance, particularly less aggravation of diabetes mellitus.
Metozalone is what type of drug?
Thiazide-like
Diuretic-resistant oedema can be treated with a loop diuretic combined with a thiazide or related diuretic except in what circumstances?
Diuretic-resistant oedema (except lymphoedema and oedema due to peripheral venous stasis or calcium-channel blockers) can be treated with a loop diuretic combined with a thiazide or related diuretic (e.g. bendroflumethiazide or metolazone).
Loop diuretics can exacerbate what metabolic condition?
Loop diuretics can exacerbate diabetes (but hyperglycaemia is less likely than with thiazides) and gout. If there is an enlarged prostate, urinary retention can occur, although this is less likely if small doses and less potent diuretics are used initially.
Loop diuretics can exacerbate diabetes but hyperglycaemia is less likely than with what?
Loop diuretics can exacerbate diabetes (but hyperglycaemia is less likely than with thiazides) and gout. If there is an enlarged prostate, urinary retention can occur, although this is less likely if small doses and less potent diuretics are used initially.
The use of loop diuretics can cause urinary retention if what is present?
An enlarged prostate.
Although this is less likely if small doses and less potent diuretics are used initially.
Furosemide and bumetanide are loop diuretics which have similar activity. Both act within how long of oral administration?
Furosemide and bumetanide are similar in activity; both act within 1 hour of oral administration and diuresis is complete within 6 hours so that, if necessary, they can be given twice in one day without interfering with sleep.
Following intravenous administration furosemide has a peak effect within how long?
Furosemide and bumetanide are similar in activity; both act within 1 hour of oral administration and diuresis is complete within 6 hours so that, if necessary, they can be given twice in one day without interfering with sleep. Following intravenous administration furosemide has a peak effect within 30 minutes. The diuresis associated with these drugs is dose related.
Amiloride and triamterene on their own are what strength diuretics?
Weak.
Why are amiloride and triamterene used with thiazide or loop diuretics?
Amiloride and triamterene (blue wee) cause retention of potassium and are therefore given with thiazide or loop diuretics as a more effective alternative to potassium supplements
Why should potassium supplements not be given spironlactone?
hyperkalaemia
Administration of a potassium sparing diuretic to a patient receiving an ACE inhibitor or an ARB is not advised why?
Severe hyperkalaemia
Spironolactone potentiates thiazide or loop diuretics by antagonising what?
Aldosterone.
Spironolactone is of value in the treatment of oedema and ascites caused by cirrhosis of the liver. It can also be used in Conn’s syndrome. What is this?
Conn’s syndrome is primary hyperaldosteronism - spironolactone is given before surgery or if surgery is not appropriate at the lowest effective dose for maintenance.
Eplerenone is a potassium sparing diuretic lincensed for what uses?
- Adjunct in left ventricular dysfunction with evidence of heart failure after myocardial infarction.
- Adjunct in chronic mild heart failure with left ventricular systolic dysfunction.
Potassium-sparing diuretics are not usually necessary in the routine treatment of hypertension unless what develops?
Hypokalaemia
Mannitol is what type of diuretic?
Mannitol is an osmotic diuretic that can be used to treat cerebral oedema and raised intra-ocular pressure.
Mannitol is an osmotic diuretic used to treat what? (2)
Mannitol is an osmotic diuretic that can be used to treat cerebral oedema and raised intra-ocular pressure.
Acetazolamide is a weak diuretic used little for its diuretic effect. How does it work?
Acetazolamide = carbonic anhydrase inhibitor
What is acetazolamide used for as an unlicensed indication?
Prophylaxis against mountain sickness but it is not a substitute for acclimatisation.
Why are acetazolamide, eye drops of dorzolamide and eye drops of brinzolamide used in glaucoma?
They inhibit the formation of aqueous humour and reduce intra-ocular pressure.
Which of the following medications acts by inhibiting a membrane transport protein?
Bisoprolol Furosemide Ramipril Simvastatin Spironolactone
Furosemide is a loop diuretic which inhibits the Na+/K+/2Cl- co-transporter in the ascending loop of Henle, preventing the transport of sodium, potassium and chloride ions from the renal tubular lumen into the epithelial cell.
Bisoprolol an spironolactone are receptor antagonists that block beta1-adrenoreceptors and aldosterone receptors, respectively.
Ramipril and simvastatin are enzyme inhibitors, ramipril inhibits ACE preventing angiotensin I –> angiotensin II and simvastatin inhibits HMG Co-A reductase, preventing the synthesis of cholesterol.
