Metformin

Metformin

[500mg tablets 2 cents]

ADMINISTRATION ROUTES:

  • PO

ALTERNATIVE NAMES:

  • Arrow Metformin

ICU INDICATIONS:

  1. type 2 diabetes mellitus

PRESENTATION AND ADMINISTRATION:

  • PO:
    Metformin 250mg, 500mg, 850mg and 1000mg tablets

DOSAGE:

  • PO:
    Initially 500mg once to twice daily. Increasing to a maximum of 1000mg three times a day.

DOSAGE IN RENAL FAILURE AND RENAL REPLACEMENT THERAPY:

  • Dose in renal impairment [GFR (ml/min)]
    <10: avoid
    10-40: avoid
    >40-50: avoid
  • Dose in renal replacement therapy
    CAPD: avoid
    HD: avoid
    CVVHDF: 25-50% of dose

DOSAGE IN PAEDIATRICS:

  • PO:
    Not applicable

CLINICAL PHARMACOLOGY:

  • Metformin is an antihyperglycemic agent which improves glucose tolerance in patients with Type 2 diabetes, lowering both basal and postprandial plasma glucose. Its pharmacologic mechanisms of action are different from other classes of oral antihyperglycemic agents. Metformin decreases hepatic glucose production, decreases intestinal absorption of glucose, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization.

CONTRAINDICATIONS:

  1. Renal dysfunction
  2. Congestive heart failure requiring pharmacologic treatment.
  3. Known hypersensitivity to metformin.
  4. Acute or chronic metabolic acidosis including diabetic ketoacidosis
  5. Use of intravenous contrast for angiography or CT within previous 72 hours

WARNINGS

  • Lactic acidosis is a rare, but serious, metabolic complication that can occur due to metformin accumulation; when it occurs, it is fatal in approximately 50% of cases.

PRECAUTIONS

  • General:
    Surgical Procedures —
    Metformin therapy should be temporarily suspended for any surgical procedure (except minor procedures not associated with restricted intake of food and fluids) and should not be restarted until the patient’s oral intake has resumed and renal function has been evaluated as normal.
    Hypoglycemia —

    Hypoglycemia does not occur in patients receiving metformin alone under usual circumstances of use, but could occur when caloric intake is deficient, when strenuous exercise is not compensated by caloric supplementation, or during concomitant use with other glucose-lowering agents (such as sulfonylureas and insulin)
  • Laboratory Tests: No tests in addition to routine ICU tests are required.
  • Drug/Laboratory Test Interactions: None noted.

IMPORTANT DRUG INTERACTIONS FOR THE ICU

  • None of note

ADVERSE REACTIONS

  • Gastrointestinal:
    Diarrhoea, nausea, vomiting, flatulence, abdominal discomfort
  • Metabolic and endocrine:
    Lactic acidosis, hypoglycaemia

Critical Care Drug Manual

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