RIOMET ER (Metformin Hydrochloride) for suspension, extended release
Sun Pharmaceutical Industries Inc.
WARNING: LACTIC ACIDOSIS
-
Postmarketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension, and resistant bradyarrhythmias. The onset of metformin‑associated lactic acidosis is often subtle, accompanied only by nonspecific symptoms such as malaise, myalgias, respiratory distress, somnolence, and abdominal pain. Metformin‑associated lactic acidosis was characterized by elevated blood lactate levels (>5 mmol/Liter), anion gap acidosis (without evidence of ketonuria or ketonemia), an increased lactate/pyruvate ratio; and metformin plasma levels generally >5 mcg/mL [see Warnings and Precautions (5.1)]. -
Risk factors for metformin-associated lactic acidosis include renal impairment, concomitant use of certain drugs (e.g. carbonic anhydrase inhibitors such as topiramate), age 65 years old or greater, having a radiological study with contrast, surgery and other procedures, hypoxic states (e.g., acute congestive heart failure), excessive alcohol intake, and hepatic impairment. -
Steps to reduce the risk of and manage metformin-associated lactic acidosis in these high risk groups are provided [see Dosage and Administration (2.3), Contraindications (4), Warnings and Precautions (5.1)]. -
If metformin-associated lactic acidosis is suspected, immediately discontinue RIOMET ER and institute general supportive measures in a hospital setting. Prompt hemodialysis is recommended [see Warnings and Precautions (5.1)].
WARNING: LACTIC ACIDOSIS
See full prescribing information for complete boxed warning.
-
Postmarketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension, and resistant bradyarrhythmias. Symptoms included malaise, myalgias, respiratory distress, somnolence, and abdominal pain. Laboratory abnormalities included elevated blood lactate levels, anion gap acidosis, increased lactate/pyruvate ratio; and metformin plasma levels generally > 5 mcg/mL. (5.1) -
Risk factors include renal impairment, concomitant use of certain drugs, age ≥ 65 years old, radiological studies with contrast, surgery and other procedures, hypoxic states, excessive alcohol intake, and hepatic impairment. Steps to reduce the risk of and manage metformin-associated lactic acidosis in these high risk groups are provided in the Full Prescribing Information. (5.1) -
If lactic acidosis is suspected, discontinue RIOMET ER and institute general supportive measures in a hospital setting. Prompt hemodialysis is recommended. (5.1)
1 INDICATIONS AND USAGE
RIOMET ER is indicated as an adjunct to diet and exercise to improve glycemic control in adults and pediatric patients 10 years of age and older with type 2 diabetes mellitus.
RIOMET ER is a biguanide indicated as an adjunct to diet and exercise to improve glycemic control in adults and pediatric patients 10 years of age and older with type 2 diabetes mellitus. (1)
2 DOSAGE AND ADMINISTRATION
Adult Dosage:
-
Starting dose: 500 mg (5 mL) orally once daily, with the evening meal (2.1) -
Increase the dose in increments of 500 mg (5 mL) weekly, up to a maximum dose of 2,000 mg (20 mL) once daily, with the evening meal (2.1) -
Patients receiving metformin hydrochloride (HCl) immediate-release treatment may be switched to RIOMET ER once daily at the same total daily dose, up to 2,000 mg (20 mL) once daily (2.1)
Pediatric Dosage:
-
Starting dose: 500 mg (5 mL) orally once daily, with the evening meal
(2.2) -
Increase dosage in increments of 500 mg (5 mL) weekly up to a maximum of 2,000 mg (20 mL) once daily, with the evening meal (2.2)
Renal Impairment:
-
Prior to initiation, assess renal function with estimated glomerular
filtration rate (eGFR) (2.3) -
Do not use in patients with eGFR below 30 mL/minute/1.73 m2 (2.3) -
Initiation is not recommended in patients with eGFR between 30 to 45 mL/minute/1.73 m2 (2.3) -
Assess risk/benefit of continuing RIOMET ER if eGFR falls below 45 mL/minute/1.73 m2 (2.3) -
Discontinue if eGFR falls below 30 mL/minute/1.73 m2(2.3)
Discontinuation for Iodinated Contrast Imaging Procedures:
-
RIOMET ER may need to be discontinued at time of, or prior to, iodinated contrast imaging procedures (2.4)
Reconstitution Instructions for the Pharmacist:
-
See Full Prescribing Information for instructions (2.5).
2.1 Adult Dosage
-
Measure the RIOMET ER dose of suspension in RIOMET ER specific dosing cup supplied. -
The reconstituted suspension is 500 mg/5 mL [see Dosage and Administration (2.5)]. -
The recommended starting dose of RIOMET ER is 500 mg (5 mL) orally once daily with the evening meal. -
Increase the dose in increments of 500 mg (5 mL) weekly on the basis of glycemic control and tolerability, up to a maximum dose of 2,000 mg (20 mL) once daily with the evening meal. -
If glycemic control is not achieved with RIOMET ER 2,000 mg (20 mL) once daily, consider a trial of RIOMET ER 1,000 mg (10 mL) twice daily. If higher doses are required, switch to metformin hydrochloride (HCl) immediate-release at total daily doses up to 2,550 mg (25.5 mL) administered in divided daily doses, as described above. -
Patients receiving metformin HCl immediate-release treatment may be switched to RIOMET ER once daily at the same total daily dose, up to 2,000 mg (20 mL) once daily.
2.2 Pediatric Dosage
-
Measure the RIOMET ER dose of suspension in the RIOMET ER specific dosing cup supplied. -
The reconstituted suspension is 500 mg/5 mL [see Dosage and Administration (2.5)]. -
The recommended starting dose of RIOMET ER for pediatric patients 10 years of age and older is 500 mg (5 mL) orally once daily, with the evening meal. -
Increase dosage in increments of 500 mg (5 mL) weekly on the basis of glycemic control and tolerability, up to a maximum of 2,000 mg (20 mL) once daily with the evening meal.
2.3 Recommendations for Use in Renal Impairment
-
Assess renal function prior to initiation of RIOMET ER and periodically thereafter. -
RIOMET ER is contraindicated in patients with an estimated glomerular filtration rate (eGFR) below 30 mL/minute/1.73 m2. -
Initiation of RIOMET ER in patients with an eGFR between 30 to 45 mL/minute/1.73 m2 is not recommended. -
In patients taking RIOMET ER whose eGFR later falls below 45 mL/min/1.73 m2, assess the benefit risk of continuing therapy. -
Discontinue RIOMET ER if the patient’s eGFR later falls below 30 mL/minute/1.73 m2 [see Warnings and Precautions (5.1)].
2.4 Discontinuation for Iodinated Contrast Imaging Procedures
Discontinue RIOMET ER at the time of, or prior to, an iodinated contrast imaging procedure in patients with an eGFR between 30 and 60 mL/min/1.73 m2; in patients with a history of liver disease, alcoholism, or heart failure; or in patients who will be administered intra-arterial iodinated contrast. Re-evaluate eGFR 48 hours after the imaging procedure; restart RIOMET ER if renal function is stable.
2.5 Reconstitution Instructions for the Pharmacist
RIOMET ER is supplied as a powder for oral suspension which must be reconstituted with the accompanying diluent prior to dispensing. Both the powder and diluent contain metformin HCl.
Please read these instructions completely before you begin.
Round Bottle Pack
Step-A Remove the bottle containing Drug Pellets and Drug Diluent bottle along with RIOMET ER dosing cup from the box. Do not use if: The expiration date has passed. The bottle appears damaged or defective.
Step-B Remove the child-resistant cap (push down and turn) from the bottle containing Drug Pellets and Drug Diluent Bottle, and retain.
Step-C Pour the contents of bottle containing Drug Pellets in to the Drug Diluent bottle and discard the empty Pellet bottle (See Figure 1).
Figure 1
Step-D Close the Drug Diluent bottle with child-resistant cap.
Step-E Shake the Drug Diluent bottle continuously in an up and down direction for at least 2 full minutes. This is important for the product to mix evenly. The reconstituted suspension is 500 mg/5 mL.
Figure 2
Store reconstituted suspension in the original bottle between 20°C to 25°C (68°F to 77°F). Do not repackage.
3 DOSAGE FORMS AND STRENGTHS
For extended-release oral suspension: 47.31 grams of metformin HCl as white to off-white pellets and white to off-white diluent for reconstitution in 473 mL bottle pack
The reconstituted suspension is 500 mg/5 mL appearing as white to off-white suspension containing white to off-white pellets
For extended-release oral suspension: 47.31 grams of metformin HCl for reconstitution in 473 mL bottle pack. The reconstituted suspension is 500 mg/5 mL (3)
4 CONTRAINDICATIONS
RIOMET ER is contraindicated in patients with:
-
Severe renal impairment (eGFR below 30 mL/min/1.73 m2) [see Warnings and Precautions (5.1)]. -
Hypersensitivity to metformin. -
Acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma.
-
Severe renal impairment (eGFR below 30 mL/min/1.73 m2) (4, 5.1) -
Hypersensitivity to metformin (4) -
Acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma. (4)
5 WARNINGS AND PRECAUTIONS
-
Lactic acidosis: See boxed warning. (5.1) -
Vitamin B12 deficiency: Metformin may lower vitamin B12 levels. Measure hematological parameters annually and vitamin B12 at 2 to 3 year intervals and manage any abnormalities. (5.2) -
Hypoglycemia with Concomitant Use with Insulin and Insulin Secretagogues: Increased risk of hypoglycemia when used in combination with insulin and/or an insulin secretagogue. Lower dose of insulin or insulin secretagogue may be required (5.3)
5.1 Lactic Acidosis
There have been postmarketing cases of metformin-associated lactic acidosis, including fatal cases. These cases had a subtle onset and were accompanied by nonspecific symptoms such as malaise, myalgias, abdominal pain, respiratory distress, or increased somnolence; however, hypotension and resistant bradyarrhythmias have occurred with severe acidosis. Metformin‑associated lactic acidosis was characterized by elevated blood lactate concentrations (> 5 mmol/L), anion gap acidosis (without evidence of ketonuria or ketonemia), and an increased lactate: pyruvate ratio; metformin plasma levels were generally > 5 mcg/mL. Metformin decreases liver uptake of lactate increasing lactate blood levels which may increase the risk of lactic acidosis, especially in patients at risk.
If metformin-associated lactic acidosis is suspected, general supportive measures should be instituted promptly in a hospital setting, along with immediate discontinuation of RIOMET ER. In RIOMET ER treated patients with a diagnosis or strong suspicion of lactic acidosis, prompt hemodialysis is recommended to correct the acidosis and remove accumulated metformin (metformin hydrochloride is dialyzable with a clearance of up to 170 mL/min under good hemodynamic conditions). Hemodialysis has often resulted in reversal of symptoms and recovery.
Educate patients and their families about the symptoms of lactic acidosis and, if these symptoms occur, instruct them to discontinue RIOMET ER and report these symptoms to their healthcare provider.
For each of the known and possible risk factors for metformin-associated lactic acidosis, recommendations to reduce the risk of and manage metformin-associated lactic acidosis are provided below:
-
Renal impairment - The postmarketing metformin-associated lactic acidosis cases primarily occurred in patients with significant renal impairment.
The risk of metformin accumulation and metformin-associated lactic acidosis increases with the severity of renal impairment because metformin is substantially excreted by the kidney. Clinical recommendations based upon the patient’s renal function include [see Dosage and Administration (2.1), Clinical Pharmacology (12.3)]:
-
Before initiating RIOMET ER, obtain an estimated glomerular filtration rate (eGFR). -
RIOMET ER is contraindicated in patients with an eGFR less than 30 mL/min/1.73 m2 [see Contraindications (4)]. -
Initiation of RIOMET ER is not recommended in patients with eGFR between 30 to 45 mL/min/1.73 m2. -
Obtain an eGFR at least annually in all patients taking RIOMET ER. In patients at risk for the development of renal impairment (e.g., the elderly), renal function should be assessed more frequently. -
In patients taking RIOMET ER whose eGFR falls below 45 mL/min/1.73 m2, assess the benefit and risk of continuing therapy. -
Drug interactions - The concomitant use of RIOMET ER with specific drugs may increase the risk of metformin-associated lactic acidosis: those that impair renal function, result in significant hemodynamic change, interfere with acid-base balance, or increase metformin accumulation. Consider more frequent monitoring of patients. -
Age 65 or greater - The risk of metformin-associated lactic acidosis increases with the patient’s age because elderly patients have a greater likelihood of having hepatic, renal, or cardiac impairment than younger patients. Assess renal function more frequently in elderly patients. -
Radiologic studies with contrast - Administration of intravascular iodinated contrast agents in metformin-treated patients has led to an acute decrease in renal function and the occurrence of lactic acidosis. Stop RIOMET ER at the time of, or prior to, an iodinated contrast imaging procedure in patients with an eGFR between 30 and 60 mL/min/1.73 m2; in patients with a history of hepatic impairment, alcoholism or heart failure; or in patients who will be administered intra-arterial iodinated contrast. Re-evaluate eGFR 48 hours after the imaging procedure, and restart RIOMET ER if renal function is stable. -
Surgery and other procedures - Withholding of food and fluids during surgical or other procedures may increase the risk for volume depletion, hypotension, and renal impairment. RIOMET ER should be temporarily discontinued while patients have restricted food and fluid intake. -
Hypoxic states - Several of the postmarketing cases of metformin-associated lactic acidosis occurred in the setting of acute congestive heart failure (particularly when accompanied by hypoperfusion and hypoxemia). Cardiovascular collapse (shock), acute myocardial infarction, sepsis, and other conditions associated with hypoxemia have been associated with lactic acidosis and may cause prerenal azotemia. When such an event occurs, discontinue RIOMET ER. -
Excessive alcohol intake - Alcohol potentiates the effect of metformin on lactate metabolism. Patients should be warned against excessive alcohol intake while receiving RIOMET ER. -
Hepatic impairment - Patients with hepatic impairment have developed cases of metformin-associated lactic acidosis. This may be due to impaired lactate clearance resulting in higher lactate blood levels. Therefore, avoid use of RIOMET ER in patients with clinical or laboratory evidence of hepatic disease.
5.2 Vitamin B12 Deficiency
In clinical trials of 29 week duration with metformin HCl tablets, a decrease to subnormal levels of previously normal serum vitamin B12 levels was observed in approximately 7% of patients. Such decrease, possibly due to interference with B12 absorption from the B12-intrinsic factor complex, may be associated with anemia but appears to be rapidly reversible with discontinuation of metformin or vitamin B12 supplementation. Certain individuals (those with inadequate vitamin B12 or calcium intake or absorption) appear to be predisposed to developing subnormal vitamin B12 levels. Measure hematologic parameters on an annual basis and vitamin B12 at 2 to 3 year intervals in patients on RIOMET ER and manage any abnormalities [see Adverse Reactions (6.1)].
5.3 Hypoglycemia with Concomitant Use with Insulin and Insulin Secretagogues
Insulin and insulin secretagogues (e.g., sulfonylurea) are known to cause hypoglycemia. RIOMET ER may increase the risk of hypoglycemia when combined with insulin and/or an insulin secretagogue. Therefore, a lower dose of insulin or insulin secretagogue may be required to minimize the risk of hypoglycemia when used in combination with RIOMET ER [see Drug Interactions (7)].
6 ADVERSE REACTIONS
The following adverse reactions are also discussed elsewhere in the labeling:
-
Lactic Acidosis [see Boxed Warning and Warnings and Precautions (5.1)] -
Vitamin B12 Deficiency [see Warnings and Precautions (5.2)] -
Hypoglycemia [see Warnings and Precautions (5.3)]
The most common adverse reactions (> 5.0%) are diarrhea, nausea/vomiting, flatulence, asthenia, indigestion, abdominal discomfort, and headache. (6.1)
To report SUSPECTED ADVERSE REACTIONS, contact Sun Pharmaceutical Industries, Inc. at 1-800-818-4555 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.
6.1 Clinical Studies Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
Metformin Immediate-Release
In a U.S. clinical trial of metformin immediate-release tablet in patients with type 2 diabetes mellitus, a total of 141 patients received metformin immediate-release tablet up to 2,550 mg per day. Adverse reactions reported in greater than 5% of metformin immediate-release tablet treated patients and that were more common than in placebo-treated patients, are listed in Table 1.
Table 1: Adverse Reactions from a Clinical Trial of Metformin Occurring >5% and More Common than Placebo in Patients with Type 2 Diabetes Mellitus
Metformin Immediate-Release Tablet
(n = 141) |
Placebo
(n = 145) |
|
---|---|---|
|
53% |
12% |
|
26% |
8% |
|
12% |
6% |
|
9% |
6% |
|
7% |
4% |
|
6% |
5% |
|
6% |
5% |
Diarrhea led to discontinuation of metformin immediate-release tablet in 6% of patients. Additionally, the following adverse reactions were reported in ≥ 1% to ≤ 5% of metformin immediate-release tablet treated patients and were more commonly reported with metformin immediate-release tablet than placebo: abnormal stools, hypoglycemia, myalgia, lightheaded, dyspnea, nail disorder, rash, sweating increased, taste disorder, chest discomfort, chills, flu syndrome, flushing, palpitation.
In metformin immediate-release tablet clinical trials of 29 week duration, a decrease to subnormal levels of previously normal serum vitamin B12 levels was observed in approximately 7% of patients.
Pediatric Patients
In clinical trials with metformin in pediatric patients with type 2 diabetes mellitus, the profile of adverse reactions was similar to that observed in adults.
Metformin Extended-Release
In placebo-controlled trials, 781 patients were administered metformin extended-release tablet. Adverse reactions reported in greater than 5% of the metformin extended-release tablet patients, and that were more common in metformin extended-release tablet- than placebo-treated patients, are listed in Table 2.
Table 2: Adverse Reactions from Clinical Trials of Metformin Hydrochloride Extended-Release Tablet Occurring >5% and More Common than Placebo in Patients with Type 2 Diabetes Mellitus
Adverse Reaction |
Metformin Hydrochloride Extended- Release Tablet (n = 781) |
Placebo (n = 195) |
Diarrhea |
10% |
3% |
Nausea/Vomiting |
7% |
2% |
*Reactions that were more common in metformin hydrochloride extended-release tablet- than placebo-treated patients.
Diarrhea led to discontinuation of metformin hydrochloride extended-release tablet in 0.6% of patients. Additionally, the following adverse reactions were reported in ≥ 1.0% to ≤ 5.0% of metformin hydrochloride extended-release tablet patients and were more commonly reported with metformin hydrochloride extended-release tablet than placebo: abdominal pain, constipation, distention abdomen, dyspepsia/heartburn, flatulence, dizziness, headache, upper respiratory infection, taste disturbance.
6.2 Postmarketing Experience
The following adverse reactions have been identified during post approval use of metformin. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Cholestatic, hepatocellular, and mixed hepatocellular liver injury have been reported with postmarketing use of metformin.
7 DRUG INTERACTIONS
Table 3 presents clinically significant drug interactions with RIOMET ER.
Table 3: Clinically Significant Drug Interactions with RIOMET ER
Carbonic Anhydrase Inhibitors |
|
Clinical Impact: |
Carbonic anhydrase inhibitors frequently cause a decrease in serum bicarbonate and induce non-anion gap, hyperchloremic metabolic acidosis. Concomitant use of these drugs with RIOMET ER may increase the risk for lactic acidosis. |
Intervention: |
Consider more frequent monitoring of these patients. |
Examples: |
Topiramate, zonisamide, acetazolamide or dichlorphenamide. |
Drugs that Reduce Metformin Clearance |
|
Clinical Impact: |
Concomitant use of drugs that interfere with common renal tubular transport systems involved in the renal elimination of metformin (e.g., organic cationic transporter-2 [OCT2] / multidrug and toxin extrusion [MATE] inhibitors) could increase systemic exposure to metformin and may increase the risk for lactic acidosis [see Clinical Pharmacology (12.3)]. |
Intervention: |
Consider the benefits and risks of concomitant use with RIOMET ER. |
Examples: |
Ranolazine, vandetanib, dolutegravir, and cimetidine. |
Alcohol and Medications Containing Alcohol |
|
Clinical Impact: |
Alcohol is known to potentiate the effect of metformin on lactate metabolism. Further, consuming alcohol or oral liquid medications containing alcohol (e.g. cough/cold or pain medications) concomitantly with RIOMET ER can accelerate the release and absorption of metformin [see Clinical Pharmacology (12.3)]. |
Intervention: |
Warn patients against excessive alcohol intake while receiving RIOMET ER and not to consume alcohol or medications containing alcohol concurrently with RIOMET ER. |
Insulin Secretagogues or Insulin |
|
Clinical Impact: |
Coadministration of RIOMET ER with an insulin secretagogue (e.g., sulfonylurea) or insulin may increase the risk of hypoglycemia. |
Intervention: |
Patients receiving an insulin secretagogue or insulin may require lower doses of the insulin secretagogue or insulin. |
Drugs Affecting Glycemic Control |
|
Clinical Impact: |
Certain drugs tend to produce hyperglycemia and may lead to loss of glycemic control. |
Intervention: |
When such drugs are administered to a patient receiving RIOMET ER, observe the patient closely for loss of blood glucose control. When such drugs are withdrawn from a patient receiving RIOMET ER, observe the patient closely for hypoglycemia. |
Examples: |
Thiazides and other diuretics, corticosteroids, phenothiazines, thyroid products, estrogens, oral contraceptives, phenytoin, nicotinic acid, sympathomimetics, calcium channel blockers, and isoniazid. |
-
Carbonic anhydrase inhibitors may increase risk of lactic acidosis. Consider more frequent monitoring (7) -
Drugs that reduce metformin clearance (such as ranolazine, vandetanib, dolutegravir, and cimetidine) may increase the accumulation of metformin. Consider the benefits and risks of concomitant use (7) -
Warn patients against excessive alcohol intake while receiving RIOMET ER and not to consume alcohol or medications containing alcohol concurrently with RIOMET ER (7)
8 USE IN SPECIFIC POPULATIONS
-
Females and Males of Reproductive Potential: Advise premenopausal females of the potential for an unintended pregnancy. (8.3) -
Geriatric Use: Assess renal function more frequently. (8.5) -
Hepatic Impairment: Avoid use in patients with hepatic impairment. (8.7)
8.1 Pregnancy
Risk Summary
Limited data with metformin in pregnant women are not sufficient to determine a drug-associated risk for major birth defects or miscarriage. Published studies with metformin use during pregnancy have not reported a clear association with metformin and major birth defect or miscarriage risk [see Data]. There are risks to the mother and fetus associated with poorly controlled diabetes mellitus in pregnancy [see Clinical Considerations].
No adverse developmental effects were observed when metformin was administered to pregnant Sprague Dawley rats and rabbits during the period of organogenesis at doses up to 2-and 5‑times, respectively, a 2,550 mg clinical dose, based on body surface area [see Data].
The estimated background risk of major birth defects is 6 to 10% in women with pre-gestational diabetes mellitus with an HbA1C >7 and has been reported to be as high as 20 to 25% in women with a HbA1C >10. The estimated background risk of miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively.
Clinical Considerations
Disease-associated maternal and/or embryo/fetal risk
Poorly-controlled diabetes mellitus in pregnancy increases the maternal risk for diabetic ketoacidosis, pre-eclampsia, spontaneous abortions, preterm delivery, and delivery complications. Poorly controlled diabetes mellitus increases the fetal risk for major birth defects, stillbirth, and macrosomia related morbidity.
Data
Human Data
Published data from post-marketing studies have not reported a clear association with metformin and major birth defects, miscarriage, or adverse maternal or fetal outcomes when metformin was used during pregnancy. However, these studies cannot definitely establish the absence of any metformin-associated risk because of methodological limitations, including small sample size and inconsistent comparator groups.
Animal Data
Metformin hydrochloride did not adversely affect development outcomes when administered to pregnant rats and rabbits at doses up to 600 mg/kg/day. This represents an exposure of about 2 and 5 times a 2,550 mg clinical dose based on body surface area comparisons for rats and rabbits, respectively. Determination of fetal concentrations demonstrated a partial placental barrier to metformin.
8.2 Lactation
Risk Summary
Limited published studies report that metformin is present in human milk [see Data]. However, there is insufficient information to determine the effects of metformin on the breastfed infant and no available information on the effects of metformin on milk production. Therefore, the developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for RIOMET ER and any potential adverse effects on the breastfed child from RIOMET ER or from the underlying maternal condition.
Data
Published clinical lactation studies report that metformin is present in human milk which resulted in infant doses approximately 0.11% to 1% of the maternal weight-adjusted dosage and a milk/plasma ratio ranging between 0.13 and 1. However, the studies were not designed to definitely establish the risk of use of metformin during lactation because of small sample size and limited adverse event data collected in infants.
8.3 Females and Males of Reproductive Potential
Discuss the potential for unintended pregnancy with premenopausal women as therapy with metformin may result in ovulation in some anovulatory women.
8.4 Pediatric Use
The safety and effectiveness of RIOMET ER as an adjunct to diet and exercise to improve glycemic control in pediatric patients 10 years of age and older with type 2 diabetes mellitus have been established. Use of RIOMET ER for this indication is supported by evidence from adequate and well-controlled studies of metformin HCl immediate-release tablet in adults with additional data from a controlled clinical study using metformin HCl immediate-release tablets in pediatric patients 10 to 16 years old with type 2 diabetes mellitus [see Clinical Studies (14.1)].
Safety and effectiveness of RIOMET ER have not been established in pediatric patients less than 10 years old.
8.5 Geriatric Use
Controlled clinical studies of metformin HCl immediate-release tablet and HCl extended-release tablet did not include sufficient numbers of elderly patients to determine whether they respond differently from younger patients. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy and the higher risk of lactic acidosis. Assess renal function more frequently in elderly patients [see Warnings and Precautions (5.1)].
8.6 Renal Impairment
Metformin is substantially excreted by the kidney, and the risk of metformin accumulation and lactic acidosis increases with the degree of renal impairment. RIOMET ER is contraindicated in severe renal impairment, patients with an estimated glomerular filtration rate (eGFR) below 30 mL/min/1.73 m2 [see Dosage and Administration (2.3), Contraindications (4), Warnings and Precautions (5.1), and Clinical Pharmacology (12.3)].
8.7 Hepatic Impairment
Use of metformin in patients with hepatic impairment has been associated with some cases of lactic acidosis. RIOMET ER is not recommended in patients with hepatic impairment [see Warnings and Precautions (5.1)].
10 OVERDOSAGE
Overdose of metformin HCl has occurred, including ingestion of amounts greater than 50 grams. Hypoglycemia was reported in approximately 10% of cases, but no causal association with metformin hydrochloride has been established. Lactic acidosis has been reported in approximately 32% of metformin overdose cases [see Warnings and Precautions (5.1)]. Metformin is dialyzable with a clearance of up to 170 mL/min under good hemodynamic conditions. Therefore, hemodialysis may be useful for removal of accumulated drug from patients in whom metformin overdosage is suspected.
11 DESCRIPTION
RIOMET ER (metformin hydrochloride for extended-release oral suspension) is a biguanide. The chemical name of metformin hydrochloride is N,N-dimethylimidodicarbonimidic diamide hydrochloride. The structural formula is as shown below:
Metformin hydrochloride, USP is a white crystalline powder with a molecular formula of C4H11N5HCl and a molecular weight of 165.62. It is freely soluble in water, slightly soluble in alcohol; practically insoluble in acetone and in methylene chloride. The pKa of metformin is 12.4. The pH of a 1% aqueous solution of metformin hydrochloride, USP is 6.37 to 6.53.
RIOMET ER is available as follows:
-
16 oz. Round Bottle Pack containing white to off-white pellets containing 37.85 g of metformin HCl (equivalent to 29.52 g metformin base) in drug pellets bottle and white to off-white dispersion containing 9.46 g of metformin hydrochloride (equivalent to 7.38 g metformin base) in drug diluent bottle intended for reconstitution.
Following reconstitution, the volume of the oral suspension is 473.12 mL (16 oz.) containing 500 mg/5mL metformin HCl equivalent to 389.95 mg metformin base.
The oral suspension include the following inactive ingredients: carboxymethyl cellulose sodium, colloidal silicon dioxide, dibutyl sebacate, ethyl cellulose, hypromellose, magnesium stearate, methyl paraben, microcrystalline cellulose, propyl paraben, sucralose, strawberry flavor Type FL # 28082 (flavoring ingredients, propylene glycol and glycerin) xanthan gum and xylitol.
12 CLINICAL PHARMACOLOGY
12.1 Mechanism of Action
Metformin is an antihyperglycemic agent which improves glucose tolerance in patients with type 2 diabetes mellitus, lowering both basal and postprandial plasma glucose. Metformin decreases hepatic glucose production, decreases intestinal absorption of glucose, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization. With metformin therapy, insulin secretion remains unchanged while fasting insulin levels and day-long plasma insulin response may decrease.
12.3 Pharmacokinetics
Mean (±SD) |
Tmax (hr)# Median (Range) |
AUC0-t
Mean (±SD) |
t1/2 (hr) Mean (±SD) |
|
Fasting condition (N = 52) |
1067.56 ± 377.11 |
(3.50 to 6.50) |
7472.02 ± 1946.10 |
4.63 ± 1.97 |
Fed condition (N = 52) |
815.39 ± 180.15 |
5.50 (3.50 to 10.00) |
7694.78 ± 1692.11 |
4.19 ± 1.03 |
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13 NONCLINICAL TOXICOLOGY
13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility
Long-term carcinogenicity studies have been performed in rats (dosing duration of 104 weeks) and mice (dosing duration of 91 weeks) at doses up to and including 900 mg/kg/day and 1500 mg/kg/day, respectively. These doses are both approximately 3 times the maximum recommended human daily dose of 2,550 mg based on body surface area comparisons. No evidence of carcinogenicity with metformin was found in either male or female mice. Similarly, there was no tumorigenic potential observed with metformin in male rats. There was, however, an increased incidence of benign stromal uterine polyps in female rats treated with 900 mg/kg/day.
There was no evidence of a mutagenic potential of metformin in the following in vitro tests: Ames test (S. typhimurium), gene mutation test (mouse lymphoma cells), or chromosomal aberrations test (human lymphocytes). Results in the in vivo mouse micronucleus test were also negative.
Fertility of male or female rats was unaffected by metformin when administered at doses as high as 600 mg/kg/day, which is approximately 2 times the maximum recommended human daily dose of 2,550 mg based on body surface area comparisons.
14 CLINICAL STUDIES
14.1 Metformin HCL Immediate-Release
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14.2 Metformin HCL Extended-Release
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Placebo |
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500 mg Once Daily |
1,000 mg Once Daily |
1,500 mg Once Daily |
2,000 mg Once Daily |
1,000 mg Twice Daily |
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Hemoglobin A1c (%) |
(n = 115) |
(n = 115) |
(n = 111) |
(n = 125) |
(n = 112) |
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Baseline |
8.2 |
8.4 |
8.3 |
8.4 |
8.4 |
8.4 |
Change at FINAL VISIT |
–0.4 |
–0.6 |
–0.9 |
–0.8 |
–1.1 |
0.1 |
p-valuea |
< 0.001 |
< 0.001 |
< 0.001 |
< 0.001 |
< 0.001 |
– |
FPG (mg/dL) |
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Baseline |
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Change at FINAL VISIT |
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p-valuea |
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Metformin HCl Immediate-Release Tablet 500 mg Twice Daily |
Metformin HCl Extended-Release Tablet |
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1,000 mg Once Daily |
1,500 mg Once Daily |
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16 HOW SUPPLIED/STORAGE AND HANDLING
16.1 How Supplied
Package Configuration |
NDC |
Description |
Supplied as |
16 oz (473 mL) Round Bottle Pack |
10631-019-17 |
White to off-white pellets containing 37.85 g of metformin HCl in drug pellets bottle and white to off-white dispersion containing 9.46 g of metformin HCl in drug diluent bottle intended for reconstitution. |
Carton contains 1 bottle of drug pellets, 1 bottle of diluent, and one dosing cup. |
16.2 Storage
Store between 20°C to 25°C (68°F to 77°F) in the original bottle. Do not repackage.
Excursions permitted between 15°C and 30°C (59°F and 86°F). [See USP Controlled Room Temperature.]
The shelf-life of the constituted oral suspension is 100 days. Any unused portion of the reconstituted suspension must be discarded after 100 days.
17 PATIENT COUNSELING INFORMATION
Patient Package Insert
RIOMET (ree oh met) ER
(metformin hydrochloride)
for extended-release oral suspension
What is the most important information I should know about RIOMET ER?
RIOMET ER can cause serious side effects including:
Lactic acidosis. Metformin hydrochloride, the medicine in RIOMET ER, can cause a rare, but serious side effect called lactic acidosis (a buildup of lactic acid in the blood) that can cause death. Lactic acidosis is a medical emergency and must be treated in the hospital.
Stop taking RIOMET ER and call your healthcare provider right away if you get any of the following symptoms of lactic acidosis:
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You have a higher chance for getting lactic acidosis if you:
-
have moderate to severe kidney problems. See “Do not take RIOMET ER if you” -
have liver problems. -
have congestive heart failure that requires treatment with medicines. -
drink a lot of alcohol (very often or short-term “binge” drinking). -
get dehydrated (lose a large amount of body fluids). This can happen if you are sick with a fever, vomiting, or diarrhea. Dehydration can also happen when you sweat a lot with activity or exercise and do not drink enough fluids -
have certain x-ray tests with injectable dyes or contrast agents. -
have surgery. -
have a heart attack, severe infection, or stroke. -
are 65 years of age or older.
Tell your healthcare provider if you have any of the problems in the list above.
Tell your healthcare provider that you are taking RIOMET ER before you have surgery or x-ray tests. Your healthcare provider may need to stop RIOMET ER for a while if you have surgery or certain x-ray tests.
RIOMET ER can have other serious side effects. See “What are the possible side effects of RIOMET ER?”
What is RIOMET ER?
-
RIOMET ER is a prescription medicine that contains metformin hydrochloride. RIOMET ER is used with diet and exercise to help control high blood sugar (hyperglycemia) in adults and children 10 years of age and older with type 2 diabetes.
It is not known if RIOMET ER is safe and effective in children under 10 years of age.
Do not take RIOMET ER if you:
-
have severe kidney problems. -
are allergic to the metformin hydrochloride or any of the ingredients in RIOMET ER. See the end of this Patient Information leaflet for a complete list of ingredients in RIOMET ER. -
have a condition called metabolic acidosis or diabetic ketoacidosis (high levels of certain acids called “ketones” in your blood or urine).
Before taking RIOMET ER, tell your healthcare provider about all of your medical conditions, including if you:
-
have a history or risk for diabetic ketoacidosis. See “Do not take RIOMET ER if you” -
have kidney problems. -
have certain x-ray tests with injectable dyes or contrast agents. -
are going to have surgery or other procedures for which you need to restrict the amount of food and liquid you eat and drink. -
have liver problems. -
have heart problems, including congestive heart failure. -
are 65 years or older. -
drink alcohol. -
are taking insulin or a sulfonylurea medicine. -
are pregnant or plan to become pregnant. It is not known if RIOMET ER will harm your unborn baby. If you are pregnant, talk with your healthcare provider about the best way to control your blood sugar while you are pregnant. -
are a premenopausal woman who does not have periods regularly or at all. RIOMET ER can cause the release of an egg from an ovary in a woman (ovulation). This can increase your chance of getting pregnant. -
are breastfeeding or plan to breastfeed. RIOMET ER can pass into your breast milk. Talk with your healthcare provider about the best way to feed your baby while you take RIOMET ER.
Tell your healthcare provider about all the medicines you take, including prescription and over-the-counter medicines, vitamins, and herbal supplements. Know the medicines you take. Keep a list of them to show your healthcare provider and pharmacist when you get a new medicine.
RIOMET ER may affect the way other medicines work, and other medicines may affect how RIOMET ER works.
How should I take RIOMET ER?
-
Take RIOMET ER exactly as your healthcare provider tells you. -
Use the RIOMET ER specific dosing cup to measure your dose. Ask your pharmacist for a dosing cup if you do not have one. -
RIOMET ER should be taken with your evening meals to help decrease an upset stomach. -
When your body is under some type of stress, such as fever, trauma (such as a car accident), infection, or surgery, the amount of diabetes medicine that you need may change. Tell your healthcare provider right away if you have any of these problems. -
Your healthcare provider should do blood tests to check how well your kidneys are working before and during your treatment with RIOMET ER. -
Your healthcare provider will check your diabetes with regular blood tests, including your blood sugar levels and your hemoglobin A1c. -
Low blood sugar (hypoglycemia) can happen more often when RIOMET ER is taken with certain other diabetes medicines. Talk to your healthcare provider about how to prevent, recognize and manage low blood sugar. See “What are the possible side effects of RIOMET ER?” -
Check your blood sugar as your healthcare provider tells you to. -
Stay on your prescribed diet and exercise program while taking RIOMET ER.
If you take too much RIOMET ER, call your healthcare provider, or go to the nearest hospital emergency room right away.
What should I avoid while taking RIOMET ER?
Do not drink a lot of alcoholic drinks while taking RIOMET ER. This means you should not binge drink for short periods, and you should not drink a lot of alcohol on a regular basis. Alcohol can increase your chance of getting lactic acidosis. Also, don’t drink alcohol at the same time you take RIOMET ER because it can speed up how fast the medicine gets into your body.
What are the possible side effects of RIOMET ER?
RIOMET ER may cause serious side effects, including:
-
See “What is the most important information I should know about RIOMET ER?” -
Low vitamin B12 (vitamin B12 deficiency). Using RIOMET ER may cause a decrease in the amount of vitamin B12 in your blood, especially if you have had low vitamin B12 levels before. Your healthcare provider may do blood tests to check your vitamin B12 levels. -
Low blood sugar (hypoglycemia). If you take RIOMET ER with another medicine that can cause lower blood sugar, such as a sulfonylurea or insulin, your risk of getting low blood sugar is higher. The dose of your sulfonylurea medicine or insulin may need to be lowered while you take RIOMET ER. Signs and symptoms of low blood sugar may include:
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These are not all the possible side effects of RIOMET ER. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
-
Store at room temperature between 68°F to 77°F (20°C to 25°C) in the original bottle. -
Throw away (discard) any unused portion of the mixed (reconstituted) suspension in the household trash after 100 days.
Keep RIOMET ER and all medicines out of the reach of children.
You can ask your pharmacist or healthcare provider for information about RIOMET ER that is written for health professionals.
For more information call 1-800-818-4555.
This Patient Information has been approved by the U.S. Food and Drug Administration. 08/2019
Instructions for Use
RIOMET (ree oh met) ER
(metformin hydrochloride)
for extended-release oral suspension
Read this Instructions for Use for RIOMET ER before you start taking it and each time you get a refill. There may be new information. This leaflet does not take the place of talking to your healthcare provider about your medical condition or treatment.
Important information: Check the expiration date printed on the bottle. Do not use if the expiration date has passed or if the bottle appears damaged or defective. See Figure A.
Figure A
Step 1. Shake the bottle well for at least 10 seconds before each use. See Figure B.
Figure B
Step 2. Remove the child-resistant cap (push down and turn) from the bottle.
Push down and turn the cap in the direction of the arrow as shown in Figure C.
Figure C
Step 3. Pour your prescribed dose in the RIOMET ER dosing cup provided by your pharmacist and take by mouth. See Figure D.
Figure D
Step 4. Close the bottle with the child-resistant cap by turning the cap clockwise. See Figure E.
Figure E
Step 5. Clean the RIOMET ER dosing cup with water only after each use and store in the box.
Step 6. Throw away (dispose of) any unused portion of the mixed (reconstituted) suspension medicine in the household trash after 100 days.
How to store RIOMET ER
-
Store RIOMET ER at room temperature between 68° F to 77° F (20° C to 25° C) in the original bottle. -
Keep RIOMET ER and all medicines out of the reach of children.
Manufactured by:
Sun Pharmaceutical Industries Limited
MOHALI, INDIA
Distributed by:
Sun Pharmaceutical Industries, Inc.
Cranbury, NJ 08512
FDA-01
This Instructions for Use has been approved by the U.S. Food and Drug Administration. 08/2019
PACKAGE/LABEL PRINCIPAL DISPLAY PANEL
Contains Drug Pellets
NDC 10631-019-17
RIOMET ER™
(metformin hydrochloride for extended-release oral suspension)
500 mg per 5 mL
(when reconstituted with Drug Diluent Bottle)
Attention Pharmacist: Drug Pellets MUST be mixed INTO the accompanying Drug Diluent Bottle
Drug Diluent Bottle for RIOMET ER™
NDC 10631-019-17
Attention Pharmacist: Reconstitute with Drug Pellet Bottle prior to dispensing
RIOMET ER™
(metformin hydrochloride for extended-release oral suspension)
500 mg per 5 mL
(when reconstituted)
PHARMACIST: Dispense the enclosed Instructions for Use to each patient
SHAKE WELL FOR AT LEAST 10 SECONDS BEFORE EACH USE
For Oral Use Only
Rx only
Package/Label Display Panel
NDC 10631-019-17
RIOMET ER™
(metformin hydrochloride for extended-release oral suspension)
500 mg per 5 mL
(when reconstituted)
PHARMACIST: Dispense the enclosed Instructions for Use to each patient
For Oral Use Only
Pharmacist: Riomet ER must be reconstituted with the enclosed diluent prior to dispensing. See side panel for instructions.
Rx only