BASIC - CARDIOVASCULAR + DERMATOLOGY Flashcards
Names of loop diuretics?
Furosemide, bumetanide
Indications of loop diuretics?
Acute pulmonary oedema (with O2 and nitrates)
Chronic heart failure
Other oedematous states (renal and liver disease)
Mechanism of action of loop diuretics?
- Act on ascending limb of loop of Henle – inhibit Na/K/2Cl co-transporter (from lumen to epithelial cell)
- Stops water following by osmosis
- Dilatation of capacitance veins – reduces preload and improves contractile function of heart failure
Side effects of loop diuretics?
- Dehydration
- Hypotension
- Low electrolytes (Na, K, Cl, Ca, Mg)
- Tinnitus and hearing loss
Contraindications of loop diuretics?
- Dehydration/Hypovolaemia
- Hepatic encephalopathy (hypokalaemia cause/worsen coma)
Cautions of loop diuretics?
- Electrolyte disturbances (low K, Na)
- Worsens gout – inhibit uric acid excretion
Interactions of loop diuretics?
- Affect drugs excreted by kidneys
o E.g. lithium levels increase and digoxin toxicity by hypokalaemia - Increase ototoxicity and nephrotoxicity of aminoglycosides
Dose of loop diuretics?
o Oral/IV furosemide 40g
o Oral 1mg bumetanide (500mg if elderly)
o Oral doses taken in morning (second dose in early afternoon when BDS) to avoid nocturia
Communication to patient of loop diuretics?
o Medicine will cause urine to be passed more
o Aim for weight loss of no more than 1kg/day
Monitoring of loop diuretics?
o U&Es during treatment
Names of thiazide diuretics?
Bendroflumethiazide, indapamide, chlortalidone, metolazone
Indications of thiazide diuretics?
- Hypertension add-on (step 3)
- Alternative first-line hypertension when CCB cannot be used (HF, oedema)
Mechanism of action of thiazide diuretics?
- Inhibit Na/Cl co-transporter in distal convoluted tubule
- Prevents sodium and water reabsorption
Side Effects of thiazide diuretics?
- Hyponatraemia
- Hypokalaemia
- Cardiac arrhythmias
- Increase glucose, HDLs and triglycerides
- Impotence in men
Contraindications of thiazide diuretics?
- Hypokalaemia
- Hyponatraemia
- Gout
- Hypercalcaemia
- Addison’s Disease
- History of allergy to sulphonamides
Changes in renal failure of thiazide diuretics?
- Ineffective in eGFR<30
- Metolazone effective if eGFR<30
Changes in liver failure of thiazide diuretics?
- Caution mild-to-moderate
- Avoid in severe liver disease
Interactions of thiazide diuretics?
- NSAIDs reduce effectiveness
- Combination of loop and thiazide diuretics lower serum K
Dose of thiazide diuretics?
- Taken orally, regularly
- Indapamide 2.5mg OD used for hypertension
- Take in morning
Monitoring of thiazide diuretics?
U&Es before starting, 2-4 weeks into therapy and after change in dose
Names of K-sparing diuretics?
Amiloride (as co-amilofruse/co-amilozide), spironolactone, eplerenone
Indications of amiloride and spironolactone?
Amiloride - Hypokalaemia (arising from diuretic therapy)
Spironolactone - Ascites and oedema from liver cirrhosis, CHF, Hypertension (resistant), Nephrotic syndrome
Primary hyperaldosteronism
Mechanism of amiloride and spironolactone?
- Amiloride
o Weak diuretic but can counter-act potassium loss
o Inhibits Na and water reabsorption by ENaC in distal convoluted tubule - Spironolactone
o Competitively bind to aldosterone receptors affecting ENaC in distal convoluted tubule
o Increases potassium retention and increases water and Na excretion
Side effects of K-sparing diuretics?
- GI upset
- Dizziness, hypotension and urinary symptoms
- Hyperkalaemia
- Spironolactone only – gynaecomastia, jaundice, liver impairment, SJS (bullous skin eruption)