Lactic acidosis is a rare, but serious, metabolic complication that can occur due to metformin accumulation during treatment with RIOMET; when it occurs, it is fatal in approximately 50% of cases. Lactic acidosis may also occur in association with a number of pathophysiologic conditions, including diabetes mellitus, and whenever there is significant tissue hypoperfusion and hypoxemia. Lactic acidosis is characterized by elevated blood lactate levels (> 5 mmol/L), decreased blood pH, electrolyte disturbances with an increased anion gap, and an increased lactate/pyruvate ratio. When metformin is implicated as the cause of lactic acidosis, metformin plasma levels > 5 µg/mL are generally found.
The reported incidence of lactic acidosis in patients receiving metformin hydrochloride is very low (approximately 0.03 cases/1000 patient-years, with approximately 0.015 fatal cases/1000 patient-years). In more than 20,000 patient-years exposure to metformin in clinical trials, there were no reports of lactic acidosis. Reported cases have occurred primarily in diabetic patients with significant renal insufficiency, including both intrinsic renal disease and renal hypoperfusion, often in the setting of multiple concomitant medical/surgical problems and multiple concomitant medications. Patients with congestive heart failure requiring pharmacologic management, in particular those with unstable or acute congestive heart failure who are at risk of hypoperfusion and hypoxemia, are at increased risk of lactic acidosis. The risk of lactic acidosis increases with the degree of renal dysfunction and the patient’s age. The risk of lactic acidosis may, therefore, be significantly decreased by regular monitoring of renal function in patients taking RIOMET and by use of the minimum effective dose of RIOMET. In particular, treatment of the elderly should be accompanied by careful monitoring of renal function. RIOMET treatment should not be initiated in patients ≥80 years of age unless measurement of creatinine clearance demonstrates that renal function is not reduced, as these patients are more susceptible to developing lactic acidosis. In addition, RIOMET should be promptly withheld in the presence of any condition associated with hypoxemia, dehydration, or sepsis. Because impaired hepatic function may significantly limit the ability to clear lactate, RIOMET should generally be avoided in patients with clinical or laboratory evidence of hepatic disease. Patients should be cautioned against excessive alcohol intake, either acute or chronic, when taking RIOMET, since alcohol potentiates the effects of metformin hydrochloride on lactate metabolism. In addition, RIOMET should be temporarily discontinued prior to any intravascular radiocontrast study and for any surgical procedure (see also PRECAUTIONS).
The onset of lactic acidosis often is subtle, and accompanied only by nonspecific symptoms such as malaise, myalgias, respiratory distress, increasing somnolence, and nonspecific abdominal distress. There may be associated hypothermia, hypotension, and resistant bradyarrhythmias with more marked acidosis. The patient and the patient’s physician must be aware of the possible importance of such symptoms and the patient should be instructed to notify the physician immediately if they occur (see also PRECAUTIONS). RIOMET should be withdrawn until the situation is clarified. Serum electrolytes, ketones, blood glucose and, if indicated, blood pH, lactate levels, and even blood metformin levels may be useful. Once a patient is stabilized on any dose level of RIOMET, gastrointestinal symptoms, which are common during initiation of therapy, are unlikely to be drug related. Later occurrence of gastrointestinal symptoms could be due to lactic acidosis or other serious disease.
Levels of fasting venous plasma lactate above the upper limit of normal but less than 5 mmol/L in patients taking RIOMET do not necessarily indicate impending lactic acidosis and may be explainable by other mechanisms, such as poorly controlled diabetes or obesity, vigorous physical activity, or technical problems in sample handling. (See also PRECAUTIONS.)
Lactic acidosis should be suspected in any diabetic patient with metabolic acidosis lacking evidence of ketoacidosis (ketonuria and ketonemia).
Lactic acidosis is a medical emergency that must be treated in a hospital setting. In a patient with lactic acidosis who is taking RIOMET, the drug should be discontinued immediately and general supportive measures promptly instituted. Because metformin hydrochloride is dialyzable (with a clearance of up to 170 mL/min under good hemodynamic conditions), prompt hemodialysis is recommended to correct the acidosis and remove the accumulated metformin. Such management often results in prompt reversal of symptoms and recovery. (See also CONTRAINDICATIONS and PRECAUTIONS.)
RIOMET (metformin hydrochloride oral solution) is an oral antihyperglycemic drug used in the management of type 2 diabetes.
Riomet is indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus.
Media Articles Related to Riomet (Metformin)
Metformin Won't Help Heart Patients Without Diabetes: Study
Source: MedicineNet metformin Specialty [2013.11.07]
Title: Metformin Won't Help Heart Patients Without Diabetes: Study
Category: Health News
Created: 11/6/2013 7:36:00 PM
Last Editorial Review: 11/7/2013 12:00:00 AM
Metformin could serve as a radiosensitizer to treat patients with stage III non-small cell lung cancer
Source: Lung Cancer News From Medical News Today [2013.10.25]
Treating aggressive lung cancer with the diabetes drug metformin along with radiation and chemotherapy may slow tumor growth and recurrence, suggests new preliminary findings from researchers at the Perelman School of Medicine at the University of Pennsylvania being presented during an oral abstract session October 28 at the 15th World Conference on Lung Cancer.
Metformin Won't Aid Breast Cancer Survival in Diabetics
Source: MedicineNet metformin Specialty [2013.05.15]
Title: Metformin Won't Aid Breast Cancer Survival in Diabetics
Category: Health News
Created: 5/14/2013 6:36:00 PM
Last Editorial Review: 5/15/2013 12:00:00 AM
Metformin Outperforms Common Class of Diabetes Drugs in Study
Source: MedicineNet glimepiride Specialty [2012.06.25]
Title: Metformin Outperforms Common Class of Diabetes Drugs in Study
Category: Health News
Created: 6/24/2012 2:05:00 PM
Last Editorial Review: 6/25/2012 12:00:00 AM
Metformin: Safer for Heart Than Older Diabetes Drugs?
Source: MedicineNet chlorpropamide Specialty [2011.06.29]
Title: Metformin: Safer for Heart Than Older Diabetes Drugs?
Category: Health News
Created: 6/29/2011 11:01:00 AM
Last Editorial Review: 6/29/2011 12:00:00 AM
Published Studies Related to Riomet (Metformin)
Effects of Metformin Versus Glipizide on Cardiovascular Outcomes in Patients With
Type 2 Diabetes and Coronary Artery Disease. 
OBJECTIVEThe two major classes of antidiabetic drugs, sulfonylureas and
metformin, may differentially affect macrovascular complications and mortality in
diabetic patients. We compared the long-term effects of glipizide and metformin
on the major cardiovascular events in type 2 diabetic patients who had a history
of coronary artery disease (CAD).RESEARCH DESIGN AND METHODSThis study is a
multicenter, randomized, double-blind, placebo-controlled clinical trial...
Metformin's effect on first-year weight gain: a follow-up study. 
on growth of the offspring are essentially unexplored... CONCLUSIONS: Women randomized to metformin were heavier in the first trimester,
Combination treatment with ipragliflozin and metformin: a randomized,
double-blind, placebo-controlled study in patients with type 2 diabetes mellitus. 
metformin... CONCLUSIONS: Combination treatment for 14 days with ipragliflozin and metformin
Comparison of metformin and insulin in the control of hyperglycaemia in
non-diabetic critically ill patients. 
metformin and insulin on hyperglycaemia in ICU patients... CONCLUSIONS: Both metformin and intensive insulin therapy significantly decreased
Metformin efficacy and safety for colorectal polyps: a double-blind randomized
controlled trial. 
BACKGROUND: Colorectal cancer is one of the major neoplasms and a leading cause
of cancer death worldwide, and new preventive strategies are needed to lower the
burden of this disease. Metformin, a biguanide, which is widely used for treating
diabetes mellitus, has recently been suggestive to have a suppressive effect on
tumorigenesis and cancer cell growth.
Clinical Trials Related to Riomet (Metformin)
Efficacy and Safety of Alogliptin Plus Metformin in Subjects With Type 2 Diabetes [Recruiting]
The purpose of this study is to evaluate the safety and effectiveness of alogliptin combined
with metformin, once daily (QD) or twice daily (BID), in participants with Type 2 Diabetes.
Study to Assess Safety and Pharmacokinetics (PK) of Double-Blind S-707106 Alone and in Combination With Open-Label Metformin in Patients With Type 2 Diabetes Mellitus [Recruiting]
- to evaluate the safety and PK of multiple-dose oral administration of S-707106 tablet
in fed state in patients with type 2 diabetes mellitus
- to evaluate the safety and PK of multiple-dose oral co-administration of S-707106 and
metformin in fed state in patients with type 2 diabetes mellitus
- to evaluate the effect of multiple doses of S-707106 on PK of metformin
- to evaluate the effect of multiple doses of metformin on PK of S-707106
Bioavailability of a Fixed Dose Combination Tablet With BI 10773 and Metformin Compared With the Monocomponents and Effect of Food on Bioavailability [Recruiting]
The objective of the current study is to determine the relative bioavailability of a BI
10773 / metformin fixed dose combination tablet compared to single tablets of BI 10773 and
metformin when administered together and to assess the effect of food on the bioavailability
the fixed dose combination tablet
Comparison of the Bioavailability of Metformin Between Medium Dose Linagliptin/Metformin Tablets and Medium Dose Glucophage Tablet Given With Linagliptin Tablet [Recruiting]
The data from this study will be used to compare the kinetic profile of metformin 500mg in
linagliptin/metformin fixed dose combination tablet versus Canadian metformin reference
product administered concomitantly with linagliptin 2. 5 mg tablet.
Carotid Atherosclerosis: MEtformin for Insulin ResistAnce Study [Recruiting]
Hypothesis: Treatment with metformin in overweight non-diabetic individuals with coronary
heart disease and on standard cardiovascular risk reducing agents including statins will
have a beneficial impact on carotid artery atherosclerosis compared to placebo.
Rationale: Once subjects have a heart attack, they remain at much higher than average risk
of another heart attack and stroke, despite the best current therapies to lower their
cholesterol and blood pressure and thin their blood. Many subjects with heart disease also
have problems metabolising (i. e. processing) sugar even if they do not have diabetes. There
is some evidence that metformin, a drug which improves sugar metabolism, decreases the risk
of future heart attacks in diabetic patients. However, whether metformin further reduces the
risk of heart disease beyond established treatments in people without diabetes is unknown.
Method: The investigators will test the ability metformin, a drug with proven safety, to
slow the progression of furring up (known as atherosclerosis) of blood vessels in
non-diabetic subjects with heart disease. This will be achieved by treating 2 groups of
subjects with metformin and placebo pills respectively. To measure atherosclerosis, the
investigators will carry out ultrasound scans of the big blood vessels in the neck at the
start of the study, after 1 year and after 1. 5 years of therapy. The investigators will then
be able to assess whether metformin has had a beneficial impact.
Page last updated: 2013-11-07