Prescribing in renal impairment

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  • Created by: z
  • Created on: 22-02-16 21:20

Drugs and renal impairment

  • some drugs cause nephrotoxicity
    • e.g. NSAIDs causing interstitial nephritis
  • some drugs are renally excreted
    • e.g. vancomycin
  • some drugs are both
    • e.g. gentamicin
  • some drugs are ineffective
    • bendroflumethiazide, nitrofurantoin
      • anitbacterial efficacy of nitrofurantoin based on renal secretion into UT
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eGFR to determine dose

  • use eGFR b/c Cr is crude and may be incorrect
    • use MDRD formula- useses Cr, adjusts for age, sex, ethnicity
  • BNF states cautions/contrainidcation based on degree of impairment:
    • stage 1= >90mL/min/1.73m^2 w/ other evidence of kidney damage
    • stage 2= 60-89 w/ other evidence
    • stage 3= 30-59
    • stage 4= 15-29
    • stage 5 (renal failure)= <15
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Drugs to avoid in renal impairment

  • aminoglycosides
    • nephrotoxic- use w/ extreme caution
  • metformin
    • incr risk of lactic acidosis
  • nitrofurantoin
    • not effective if GFR= <45 ml/min
  • potassium supplements/potassium sparing diuretics
    • risk of hyperkalaemia
  • lithium
    • reanlly excreted with narrow therapeutic range (careful monitorring needed if used)
  • NSAIDs
    • avoid in CKD
    • can exacerbate fluid overload and oedema

generally renal patients are more at risk of ADR

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Management of AKI

  • goal is to prevent further injury and facilitate recovery of renal function
    • asses circ vol and fluid administration
    • prevent/treat hyperkalaemia and metabolic acidosis
    • discontinue nephrotoxic drugs
    • adapt dose of renally excreted drugs 
      • reduce dose sizes/incr dose interval
    • supportive measures 
      • diuretics etc
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