Loop Diuretics Flashcards
Give two examples of loop diuretics?
- Furosemide
- Bumetanide
What are the indications for the use of furosemide or bumetanide?
- Pulmonary oedema due to heart failure
- Peripheral oedema
What causes of peripheral oedema are there where you would not use furosemide or bumetanide?
- Venous stasis
- Lymphoedema
- Calcium channel blockers
What contraindications exist with furosemide and bumetanide?
- Hypovolaemia/severe electrolyte disturbances
What cautions are there for use of furosemide and bumetanide?
- Renal impairment
- Hepatic impairment
- During pregnancy and breastfeeding
- Impaired micturition (ejection of urine through the urethra)
- Prostatic enlargement
- Gout
Where do loop diuretics work on in the kidneys?
- Thick ascending limb of the loop of henle in the renal tube
What do loop diuretics inhibit in the loop of henle?
- Na/K2Cl co transporter
What do loop diuretics inhibit the reabsorption of?
- Sodium
- Resulting in diuresis
Why are loop diuretics very effective in causing diuresis?
- Most sodium absorption occurs at this part of the loop of henle
What strange side effects can loop diuretics cause to happen when used in high doses?
- Deafness due to an electrolyte change in the endolymph (semi circular canals of the inner ear)
What do loop diuretics cause to happen systemically?
- Pulmonary and systemic vasodilation
What does the pulmonary and systemic vasodilation cause?
- Reduction in preload making treatment of pulmonary oedema even more effective
When would loop diuretics be given intravenously?
- During acute pulmonary oedema OR
- Resistant heart failure
Why should furosemide not be given quickly?
- More likely to become ototoxic
- Slow infusion of 4mg/min should be used
How are loop diuretics normally given?
- Orally
- Should be given at times of day when diuresis does not impact on life
What adverse reactions are caused by loop diuretics besides changes in blood metabolites?
- Dehydration
- Hyperglycaemia
- Precipitation of gout
What blood test should be closely monitored when on loop diuretics?
- U’s and E’s
What should loop diuretics NOT be prescribed with?
Aminoglycosides
What can happen when loop diuretics are prescribed with aminoglycosides?
- Acute renal failure
- Deafness
What can the hypokaleamia caused by loop diuretics lead to with other medication?
- Digoxin toxicity
- Anti-arrhythmic toxicity
What other interactions do loop diuretics cause?
- Reduce excretion of lithium that can lead to lithium toxicity
- Interaction with theophylline will increase risk of hypokalaemia
What should patients keep when on loop diuretics?
- Fluid balance chart
What may reduce loop diuretics efficacy in the long term?
- Patient develops resistance to them (unknown cause)
- Higher dose required
