CLINICAL USE

Diuretic (potassium-sparing)

DOSE IN NORMAL RENAL FUNCTION

150–250 mg daily in divided doses; reduce to alternate days after 1 week

PHARMACOKINETICS

  • Molecular weight &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp : 253
  • %Protein binding &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp : 60
  • %Excreted unchanged in urine &nbsp &nbsp : 5–10
  • Volume of distribution (L/kg) &nbsp &nbsp &nbsp : 2.2–3.7
  • half-life – normal/ESRD (hrs)&nbsp &nbsp &nbsp : 2/10

    DOSE IN RENAL IMPAIRMENT

    GFR (mL/MIN)

  • 20 to 50 &nbsp &nbsp : Dose as in normal renal function
  • 10 to 20 &nbsp &nbsp : Avoid. See ‘Other Information’
  • <10 &nbsp &nbsp &nbsp &nbsp &nbsp : Avoid. See ‘Other Information’

    DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

  • CAPD &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp: Unknown dialysability. Avoid

  • HD &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp : Unknown dialysability. Avoid
  • HDF/high flux &nbsp : Unknown dialysability. Avoid
  • CAV/VVHD &nbsp &nbsp &nbsp: Unknown dialysability. Avoid

    IMPORTANT DRUG INTERACTIONS

    Potentially hazardous interactions with other drugs ACE inhibitors and angiotensin-II antagonists: enhanced hypotensive effect (risk of severe hyperkalaemia)
  • Analgesics: increased risk of nephrotoxicity with NSAIDs; increased risk of hyperkalaemia, especially with indometacin; antagonism of hypotensive effect
  • Antibacterials: avoid concomitant use with lymecycline
  • Antidepressants: enhanced hypotensive effect with MAOIs; increased risk of postural hypotension with tricyclics
  • Antipsychotics: enhanced hypotensive effect with phenothiazines Antihypertensives: enhanced hypotensive effect; increased risk of first dose hypotensive effect of post-synaptic alpha- blockers, e.g. prazosin
  • Ciclosporin: increased risk of hyperkalaemia
  • Lithium: reduced excretion of lithium (risk of lithium toxicity)
  • Potassium salts: increased risk of hyperkalaemia
  • Tacrolimus: increased risk of hyperkalaemia

    ADMINISTRATION

    Reconstition

    Route

    Oral

    Rate of Administration

    Comments

    OTHER INFORMATION

    Hyperkalaemia is common when GFR<30 mL/min. May cause acute renal failure Potassium-sparing diuretics are weak diuretics and are ineffective in moderate to severe renal failure .