Rhea Metformin Hydrochloride Special Precautions

Lactic acidosis: Lactic acidosis is a rare, but serious (high mortality in the absence of prompt treatment), metabolic complication that can occur due to metformin accumulation. Reported cases of lactic acidosis in patients on metformin have occurred primarily in diabetic patients with significant renal failure. The incidence of lactic acidosis can and should be reduced by assessing also other associated risk factors such as poorly controlled diabetes, ketosis, prolonged fasting, excessive alcohol intake, hepatic insufficiency and any condition associated with hypoxia.
Diagnosis: This risk of lactic acidosis must be considered in the event of non-specific signs such as muscle cramp with digestive disorders as abdominal pain and severe asthenia.
This can be followed by acidotic dyspnea, abdominal pain, hypothermia and coma. Diagnostic laboratory findings are decreased blood pH, plasma lactate levels above 5 mmol/l, and an increased anion gap and lactate/pyruvate ratio. If metabolic acidosis is suspected, metformin should be discontinued and the patient should be hospitalized immediately (see Overdosage).
Renal function: As metformin is excreted by the kidney, creatinine clearance (this can be estimated from serum creatinine levels by using the Cockcroft-Gault formula) should be determined before initiating treatment and regularly thereafter: at least annually in patients with normal renal function; at least two to four times a year in patients with creatinine clearance at the lower 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 therapy or diuretic therapy and when starting with a non-steroidal anti-inflammatory drug (NSAID).
Administration of iodinated contrast media: The intravascular administration of iodinated contrast media in radiologic studies can lead to renal failure. This may induce metformin accumulation and may expose to lactic acidosis. Therefore metformin must be discontinued 48 hours before the test or at the time of the test and not be reinstituted until 48 hours afterwards, and only after renal function has been re-evaluated and found to be normal (see Interactions).
Surgery: Metformin must be discontinued 48 hours before elective major surgery. Therapy may be restarted no earlier than 48 hours following surgery or resumption of oral nutrition and only if normal renal function has been established.
Other precautions: Avoid consumption of alcoholic beverages.
Patients have to inform their doctor of any other treatment they are receiving and of any infectious diseases such as influenza, respiratory tract infection or urinary tract infection.
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 does not cause hypogylcemia, but caution is advised when it is used in combination with insulin or other oral antidiabetics (e.g. sulfonylureas or meglitinides).
Effect on 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 (e.g. sulfonylureas, insulin or meglitinides).
Use in children and adolescents: The diagnosis of type 2 diabetes mellitus should be confirmed before treatment with metformin is initiated.
No effect of metformin on growth and puberty has been detected during controlled clinical studies of one-year duration but no long-term data on these specific points are available. Therefore, a careful follow-up on the effect on these parameters in metformin-treated children, especially pre-pubescent children, is recommended.
Use in children aged between 10 and 12 years: Only 15 subjects aged between 10 and 12 years were included in the controlled clinical studies conducted in hepatic children and adolescents. Although metformin efficacy and safety in children below 12 did not differ from efficacy and safety in older children particular caution is recommended when prescribing to children aged between 10 and 12 years.