Metformin


Full Prescribing Info
Dosage/Direction for Use

Oral
Type 2 diabetes mellitus
Adult: Treatment: As conventional tab/solution: Initially, 500 or 850 mg bid or tid, gradually increase at intervals of at least 1 week according to response. Max: 3,000 mg daily in 3 divided doses. As extended-release tab: Initially, 500 mg daily with evening meal, increase dose in increments of 500 mg up to Max 2,000 mg daily according to response. Prophylaxis: As extended-release tab: Initially, 500 mg daily with evening meal, gradually increase dose at intervals of 10-15 days, according to response. Max: 2,000 mg daily with evening meal.
Child: ≥10 years
As conventional tab/solution: Initially, 500 or 850 mg once daily, gradually increase dose at intervals of at least 1 week according to response. Max: 2,000 mg daily in 2 or 3 divided doses.
Elderly: Adjust dose based on renal function.
Renal impairment:
eGFR <30 mL/min: Contraindicated. eGFR 30-44 mL/min: Total Max daily dose: 1,000 mg. eGFR 45-59 mL/min: Total Max daily dose: 2,000 mg daily. eGFR 60-89 mL/min: Total Max daily dose: 3,000 mg. All doses to be taken in 2-3 divided doses.
Administration
Should be taken with food.
Contraindications
Acute or chronic metabolic acidosis with or without coma, acute conditions which may alter renal function (e.g. dehydration, severe infection, shock), acute or chronic disease-causing hypoxia (e.g. unstable cardiac or respiratory failure, recent MI, shock), acute alcohol intoxication or alcoholism. Severe renal (eGFR<30 mL/min) impairment. Intravascular administration of iodinated contrast agents.
Special Precautions
Patients with risk factors for lactic acidosis, stable heart failure, dehydration, prerenal azotemia. Mild to moderate renal impairment. Hepatic impairment. Children and elderly. Pregnancy and lactation. Not indicated for use in patient with type 1 diabetes mellitus or with diabetic ketoacidosis. Monitoring Parameters Monitor glucose and ketones (urine and blood), fasting blood sugar, haemoglobin A1c at least twice yearly in stable glycaemic control; quarterly if not meeting therapy goals. Monitor renal function prior to initiation of therapy and annually thereafter; haematologic parameters at baseline and annually thereafter; vitamin B12 serum concentration every 2-3 years (prolonged use). Monitor for signs and symptoms of lactic acidosis.
Adverse Reactions
Significant: Vitamin B12 deficiency. Cardiac disorders: Chest discomfort, palpitations, dyspnoea. Gastrointestinal disorders: Nausea, vomiting, diarrhoea, abdominal pain, flatulence, heartburn/dyspepsia, abdominal distention, abnormal stools, constipation. General disorders and administration site conditions: Asthenia, flu-like symptoms, malaise. Hepatobiliary disorders: Cholestatic, hepatocellular, mixed hepatocellular liver injury. Musculoskeletal and connective tissue disorders: Myalgia, chills. Nervous system disorders: Taste disturbance, headache. Psychiatric disorders: Increased somnolence. Respiratory, thoracic and mediastinal disorders: Upper respiratory tract infection. Skin and subcutaneous tissue disorders: Nail disease, rash. Vascular disorders: Flushing.
Potentially Fatal: Lactic acidosis.
Overdosage
Symptoms: Hypoglycaemia, lactic acidosis manifested as acidotic dyspnoea, abdominal pain, muscle cramps, hypothermia followed by coma. Management: Perform haemodialysis to remove lactate and metformin in the blood.
Drug Interactions
Increased risk of hypoglycaemia with insulin and insulin secretagogues (e.g. sulfonylurea). Increased risk of lactic acidosis with carbonic anhydrase inhibitors (e.g. acetazolamide, dichlorphenamide), NSAIDs, and antihypertensive agents (e.g. ACE inhibitors). Increased plasma concentration and reduced clearance with OCT2 inhibitors (e.g. cimetidine, dolutegravir, ranolazine, trimethoprim, vandetanib, isavuconazole).
Potentially Fatal: Contrast-induced nephropathy and increased risk of lactic acidosis with iodinated contrast agents.
Food Interaction
Food decreases extent and slightly delays absorption. Increased risk of lactic acidosis with alcohol.
Action
Metformin is a biguanide antihyperglycaemic agent which improves glucose tolerance by lowering both basal and postprandial plasma glucose. It decreases hepatic glucose production by inhibiting gluconeogenesis and glycogenolysis, delays intestinal glucose absorption, and improves insulin sensitivity by enhancing peripheral glucose uptake and utilisation.
Onset: Within days.
Absorption: Slowly and incompletely absorbed from the gastrointestinal tract. Food decreases extent and slightly delays absorption. Absolute bioavailability: 50-60% (fasting); reduced if taken with food. Time to peak plasma concentration: 2-3 hours (immediate-release); 7 hours, range: 4-8 hours (extended-release).
Distribution: Distributes and concentrates in liver, kidney and gastrointestinal tract; partitions into erythrocytes. Crosses placenta and enters breastmilk (small amounts). Volume of distribution: 654 ± 358 L. Plasma protein binding: Negligible.
Metabolism: Not metabolised.
Excretion: Via urine (approx 90% as unchanged drug). Elimination half-life: 6.2 hours (plasma); approx 17.6 hours (blood).
Storage
Oral: Store below 30°C. Protect from light and moisture.
CIMS Class
ATC Classification
A10BA02 - metformin ; Belongs to the class of biguanides. Used in the treatment of diabetes.
Disclaimer: This information is independently developed by CIMS based on metformin from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to CIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, CIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 CIMS. All rights reserved. Powered by CIMSAsia.com
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