metformin hydrochloride

Drug Name

Generic Name : metformin hydrochloride

Brand Name: CO Metformin (CAN), Fortamet, Gen-Metformin (CAN), Glucophage, Glucophage XR, Glumetza, Metformin HCl ER, Nu-Metformin (CAN), ratio-Metformin (CAN), Riomet

Classification: Antidiabetic

Pregnancy Category B 

Dosage & Route

Available forms : Tablets—500, 850, 1,000 mg; ER tablets—500, 750, 1,000 mg; oral solution–500 mg/5 mL

ADULTS
  • 500–850 mg/day PO in divided doses to a maximum of 2,550 mg/day. Dose should be adjusted based on response and blood glucose level. ER tablet: Initially, 500 mg/day PO with the evening meal; may be increased by 500 mg each wk to a maximum of 2,550 mg once daily.
PEDIATRIC PATIENTS 10–16 YR
  • 500 mg/day PO in divided doses with meals; may be increased by 500 mg each wk to a maximum of 2,000 mg/day. ER tablet is not recommended.
GERIATRIC PATIENTS AND PATIENTS WITH RENAL IMPAIRMENT
  • Smaller doses may be necessary; monitor closely and adjust slowly.
Therapeutic actions
  • The exact mechanism of action of metformin is unclear but it appears to reduce glucose absorption from the GI tract, reduce gluconeogenesis and enhance insulin sensitivity by increasing peripheral glucose uptake and utilisation.
Indications
  • Adjunct to diet to lower blood glucose with type 2 diabetes mellitus in patients > 10 yr; extended-release in patients > 17 yr
  • As part of combination therapy with a sulfonylurea or insulin when either drug alone cannot control glucose levels in patients with type 2 diabetes mellitus
Adverse effects
  • Anorexia, nausea, vomiting, diarrhoea, wt loss, flatulence, occasional metallic taste; weakness; hypoglycaemia; rash, malabsorption of vit B12. Chest discomfort, flushing, palpitation, chills, headache, lightheadedness, indigestion, abdominal discomfort.
  • Potentially Fatal: Lactic acidosis in presence of renal failure and alcoholism.
Contraindications
  • Acute or chronic metabolic acidosis with or without coma (including diabetic ketoacidosis). Renal failure, severe renal or hepatic impairment, acute conditions which may affect renal function e.g. dehydration, severe infection or shock. Cardiac failure, CHF, IDDM, severe impairment of thyroid function; acute or chronic alcoholism. Acute or chronic diseases which may cause tissue hypoxia e.g. cardiac or respiratory failure, recent MI or shock. Pregnancy, lactation.
Nursing considerations
Assessment
  • History: Allergy to metformin; diabetes complicated by fever, severe infections, severe trauma, major surgery, ketosis, acidosis, coma; type 1 diabetes, serious hepatic or renal impairment, uremia, thyroid or endocrine impairment, glycosuria, hyperglycemia associated with primary renal disease, CHF, pregnancy, lactation
  • Physical: Skin color, lesions; T, orientation, reflexes, peripheral sensation; R, adventitious sounds; liver evaluation, bowel sounds; urinalysis, BUN, serum creatinine, LFTs, blood glucose, CBC
Interventions
  • Monitor urine or serum glucose levels frequently to determine effectiveness of drug and dosage.
  • WARNING: Arrange for transfer to insulin therapy during periods of high stress (infections, surgery, trauma).
  • WARNING: Use IV glucose if severe hypoglycemia occurs as a result of overdose.
Teaching points
  • Do not discontinue this medication without consulting your health care provider.
  • Monitor urine or blood for glucose and ketones as prescribed.
  • Swallow extended-release tablets whole; do not cut, crush, or chew.
  • Do not use this drug during pregnancy; if you become pregnant, consult with your health care provider for appropriate therapy.
  • Avoid using alcohol while taking this drug.
  • Report fever, sore throat, unusual bleeding or bruising, rash, dark urine, light-colored stools, hypo- or hyperglycemic reactions.