metformin hydrochloride
metformin hydrochloride.JPG

CLINICAL USE

Non-insulin dependent diabetes mellitus Polycystic ovary syndrome

DOSE IN NORMAL RENAL FUNCTION

500 mg 3 times a day; maximum 2 g daily in divided dosesPolycystic ovary syndrome: 1.5–1.7 g daily in 2–3 divided doses

PHARMACOKINETICS

  • Molecular weight                           :165.6
  • %Protein binding                           :Negligible
  • %Excreted unchanged in urine     : 100
  • Volume of distribution (L/kg)       :1–4
  • half-life – normal/ESRD (hrs)      :2–6/prolonged

    DOSE IN RENAL IMPAIRMENT

    GFR (mL/MIN)

    40–50 25–50% of dose10–40 25% of dose. See ‘Other Information’
  • <10           : Avoid. See ‘Other Information’

    DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

  • CAPD                :Unknown dialysability. Avoid
  • HD                     :Dialysed. Avoid
  • HDF/high flux   :Dialysed. Avoid
  • CAV/VVHD      :Probably dialysed. Avoid

    IMPORTANT DRUG INTERACTIONS

    Potentially hazardous interactions with other drugs
  • Alcohol: increased risk of lactic acidosis Cimetidine: Inhibits renal excretion of metformin

    ADMINISTRATION

    Reconstition

    Route

    Oral

    Rate of Administration

    Comments

    OTHER INFORMATION

    Lactic acidosis is a rare but serious metabolic complication that can occur due to metformin accumulation. Reported cases have occurred primarily in diabetic patients with significant renal impairmentAs metformin is renally excreted eGFR values should be determined before initiating treatment and regularly thereafter:at least annually in patients with —normal renal functionat least 2–4 times a year in patients —with an eGFR at the lower limit of normal and in elderly subjectsSpecial caution should be exercised in the elderly in situations where renal function may become impaired, e.g. initiating therapy with antihypertensives, diuretics



    See how to identify renal failure stages according to GFR calculation

    See how to diagnose irreversible renal disease

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