C3.2 R4(c): Clarify a medication order with a prescriber

ID: 82 yo male admitted with sepsis, secondary to infected diabetic feet.
NKDA, PMHx – Parkinson disease with dementia, atrial fibrillation, previous CVA, ischemic heart disease, orthostatic hypotension, frequent falls, hypothyroidism and depression

Order by Family Nurse Practitioner:

  • Stop metformin
  • Decrease gliclazide MR to 15mg po qam

Progress notes:

  • eGFR ~51, borderline kidney function
  • Hypoglycemia twice 3.7 in am in last 10 days – range 4.5-6.7 in am fasting
  • A/P: at risk for hypo due to age, on metformin – stop today given kidney function, decrease gliclazide MR

S/O:

Meds
  • metformin 500mg PO BID since Jul 2016
  • gliclazide 30mg MR PO daily (was on 80mg IR AM and 160mg IR PM)
  • discharged with insuln glargine from Sept 2016 admission for diabetes foot cellulitis – not on insulin during current admission
Labs HbA1c: Jul 16: 7.6%; Apr 16: 8.8%; Jan 16: 11.6%
eGFR: stable ~ 50

Issues:

  • Lowest dose of gliclazide MR = 30mg – unable to split dose of MR
    • Dose given at 800hr
  • Nurse was concerned re: hypoglycemia and renal dysfunction with metformin, but:
    • At his current renal function (stable), metformin is safe (nurse practitioner unaware of any tolerability issues with metformin).
    • Metformin has a very low risk for hypoglycemia, and as a result, is considered quite safe in the elderly

Action:

  • Called ward to let them know to hold the morning dose until I was able to speak to the prescriber
    • I had spoken to the unit clerk instead of the nurse taking care of the patient – in the future, will ask to speak to the nurse and inquire when the nurse practitioner (prescriber) is on the ward
  • Discussed with nurse practitioner on above issues – NP to reassess, and plans to continue metformin and discontinue gliclazide (patient to be discharged tomorrow). Nurse to fax new order. Aware that last HbA1c was ~6 months ago.
  • Document on order that order for stop metformin and decrease gliclazide was not entered and copied to clinical as an FYI that issue has been discussed with NP and NP to R/A

FYI Metformin in renal dysfunction:

  • Lexicomp:
    • eGFR 30-45: initiation is not recommended. may consider dose reduction by 50% (e.g. of current dose or max dose) and monitor renal function q 3 mos
    • eGFR <30: use is contraindicated
  • CCS HF Compendium guidelines: Metformin may be considered a first-line agent for diabetes treatment if the eGFR is greater than 30 mL/min. However, care should be taken to temporarily discontinue metformin if renal function worsens significantly.
  • Diabetes Care 2011:
    • eGFR 45-60: continue but monitor renal function q 3-6 mos
    • eGFR 30-45: use lower dose (e.g. 50% or half maximal dose) and monitor renal function q 3 most, and don’t start new patients on metformin
  • Renal impairment – increases risk of lactic acidosis with metformin
    • Lactic acidosis
      • symptoms: malaise, myalgias, respiratory distress, increased somnolence, abdominal distress
      • signs: low pH, increased anion gap, elevated blood lactate

My summary:

  • eGFR < 30: contraindicated
  • eGFR 30-45: do not initiate and for patients currently on metformin, use lower doses (e.g. 50% reduction or half maximal dose), monitor renal function q 3 mos
  • eGFR 45-60: ok to continue but monitor renal function q 3-6 mos
  • eGFR >60: no issue

Resource:

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