2.2.4 Potassium-sparing diuretics with other diuretics

ChoiceDrugDosage
1st choiceCo-amilofruse tablets 2.5/20 (amiloride 2.5mg, furosemide 20mg) 5/40 (amiloride 5mg, furosemide 40mg)Dose:
Oedema – co-amilofruse 2.5/20, 1 tablet in the morning; co-amilofruse 5/40, 1-2 tablets in the morning

Prescribing Notes

  • It is preferable to prescribe diuretic agents separately. Combination diuretics encourage the use of a potassium-sparing agent when a loop or thiazide diuretic alone may be more appropriate.
  • Fixed combinations of diuretics should only be considered if compliance is a problem or to reduce the risk of hypokalaemia.
  • Combination products containing a diuretic plus potassium do not contain sufficient potassium to reliably correct hypokalaemia and are not recommended.
  • Where combinations of diuretics with amiloride are prescribed generically, the prescriber must state the dose required.

Cautions

  • All diuretics have the propensity to cause postural hypotension and potentially lead to collapse and falls. Other side-effects include confusion, dehydration and urinary incontinence. Hyponatraemia is a particular problem in the frail elderly.
  • Diuretics should not be used on a long term basis to treat simple gravitational oedema. This will usually respond to increased ambulation, raising the legs and support stockings.
  • Potassium-sparing diuretics should be used with caution in renal impairment.
  • Potassium-sparing diuretics should be used with caution when co-administered with ACE inhibitors or angiotensin-II receptor antagonists due to the risk of hyperkalaemia.
  • Potassium supplements must NOT normally be given with: potassium sparing diuretics, aldosterone antagonists, in the presence of renal failure, with ACE inhibitors or with angiotensin-II receptor antagonists, due to the danger of hyperkalaemia.