Fornidd: Lactic acidosis: Metformin accumulation occurs at acute worsening of renal function and increases the risk of lactic acidosis.
In case of dehydration (severe diarrhoea or vomiting, fever or reduced fluid intake), metformin should be temporarily discontinued and contact with a health care professional is recommended.
Medicinal products that can acutely impair renal function (such as antihypertensives, diuretics and NSAIDs) should be initiated with caution in metformin-treated patients. Other risk factors for lactic acidosis are excessive alcohol intake, hepatic insufficiency, inadequately controlled diabetes, ketosis, prolonged fasting and any conditions associated with hypoxia, as well as concomitant use of medicinal products that may cause lactic acidosis (see Contraindications and Interactions).
Patients and/or care-givers should be informed of the risk of lactic acidosis. In case of suspected symptoms, the patients should stop taking metformin and seek immediate medical attention.
Diagnostic laboratory findings are decreased blood pH (<7.35), increased plasma lactate levels (>5 mmol/l) and an increased anion gap and lactate/pyruvate ratio.
Renal Function: As metformin is excreted by the kidney, serum creatinine levels should be determined before initiating treatment and regularly thereafter: At least annually in patients with normal renal function; and at least two to four times a year in patients with serum creatinine levels at the upper limit of normal and in elderly subjects. Decreased renal function in elderly subjects is frequent and asymptomatic.
Special caution should be exercised in situations where renal function may become impaired, for example when initiating antihypertensive or diuretic therapy and when starting therapy with an NSAID.
GRF should be assessed before treatment initiation and regularly thereafter, see Dosage & Administration. Metformin is contraindicated in patients with GFR <30 mL/min and should be temporarily discontinued in the presence of conditions that alter renal function, see Contraindications.
Administration of iodinated contrast agent: Intravascular administration of iodinated contrast agents may lead to contrast induced nephropathy, resulting in metformin accumulation and an increased risk of lactic acidosis.
Metformin should be discontinued prior to or at the time of the imaging procedure and not restarted until at least 48 hours after, provided that renal function has been re-evaluated and found to be stable, see Dosage & Administration and Interactions.
Surgery: Metformin must be discontinued at the time of surgery under general, spinal or epidural anesthesia.
Therapy may be restarted no earlier than 48 hours following surgery or resumption of oral nutrition and provided that renal function has been re-evaluated and found to be stable.
Other Precautions: All patients should continue their diet with a regular distribution of carbohydrate intake during the day. Overweight patients should continue their energy-restricted diet.
The usual laboratory tests for diabetes monitoring should be performed regularly.
Metformin alone never causes hypoglycemia, although caution is advised when it is used in combination with insulin or sulfonylureas.
Regular monitoring of thyroid-stimulating hormone (TSH) levels is recommended in patients with hypothyroidism (see Adverse Reactions).
Long-term treatment with metformin has been associated with a decrease in vitamin B12 serum levels which may cause peripheral neuropathy. Monitoring of the vitamin B12 levels is recommended (see Adverse Reactions).
Effects on the Ability to Drive and Use Machines: Metformin monotherapy does not cause hypoglycemia and therefore, has no effect on the ability to drive or to use machines. However, patients should be alerted to the risk of hypoglycemia when metformin is used in combination with other antidiabetic agents (sulfonylureas, insulin, repaglinide).
Fornidd XR: Adjust dose according to blood glucose levels during the first few months.
Lactation: Studies have not been conducted in nursing mothers, but caution should be exercised in such patients, and a decision should be made to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Use in Children: Safety and effectiveness in children has not been established.
Use in Elderly: As aging is associated with reduced renal function, care should be taken in dose selection and should be based on careful and regular monitoring of renal functions.