Deson PR

Metformin.

Pharmacotherapeutic Group: Antidiabetic Agent, Biguanide.
Pharmacology: Pharmacodynamics: Mechanism of Action: Decreases hepatic glucose pro­duction, decreasing intestinal absorption of glucose and improves insulin sensitivity (increases peripheral glucose uptake and utilization).
Pharmacodynamics/kinetics: Onset of action: Within days; maximum effects up to 2 weeks.
Distribution: Vd: 654 ± 358 L; partitions into erythrocytes.
Protein binding: Negligible.
Metabolism: Not metabolized by the liver.
Bioavailability: Absolute: Fasting: 50% to 60%.
Half-life Elimination: Plasma: 4-9 hours.
Time to peak, serum: Immediate release: 2-3 hours; extended release: 7 hours (range 4-8 hours).
Excretion: Urine (90% as unchanged drug; active secretion).

Management of type 2 diabetes mellitus (noninsulin dependent, NIDDM) when hyperglycemia cannot be managed with diet and exercise alone.

Take initially 1 tablet once daily with the evening meal, maximum dose 1500-2000 mg/day.
Type 2 diabetes management: Note: Allow 1-2 weeks between dose titrations: Generally, clinically significant responses are not seen at doses <1500 mg daily; how­ever, a lower recommended starting dose and gradual increased dosage is recommended to minimize gastro­intestinal symptoms.
Dosing adjustment/comments in renal impairment: The plasma and blood half-life of metformin is prolonged and the renal clearance is decreased in proportion to the decrease in creatinine clearance. Per the manufacturer, metformin is contraindicated in the presence of renal dysfunction defined as a serum creatinine 1.5 mg/dL  in males, or ≥1.4 mg/dL in females and in patients with abnormal clearance. The Canadian labeling recom­mends that metformin be avoided in patients with Cl_cr <60 mL/minute.
Dosing adjustment in hepatic impairment: Avoid met­formin; liver disease is a risk factor for the development of' lactic acidosis during metformin therapy.
Dietary Considerations: Drug may cause GI upset; take with food (to decrease GI upset). Take at the same time(s) each day. Dietary modification based on ADA recommen­dations is a part of therapy. Monitor for signs and symp­toms of vitamin B12 and/or folic acid deficiency; supplementation may be required.
Administration: Administer with a meal (to decrease GI upset). Extended release: Swallow whole; do not crush, break, or chew. Administer once daily doses with the evening meal. Fortamet should also be administered with a full glass of water.

Hypersensitivity to metformin or any ­ component of the formulation; renal disease or renal dysfunction (serum creatinine ≥1.5 mg/dL in males or ≥1.4 mg/dL in females) or abnormal creatinine clearance from any cause, including shock, acute myocardial infarc­tion, or septicemia; acute or chronic metabolic acidosis with or without coma (including diabetic ketoacidosis).
Note: Temporarily discontinue in patients undergoing radiologic studies in which intravascular iodinated contrast media are utilized.

Lactic acidosis is a rare, but potentially severe consequence of therapy with metformin. Lactic acidosis should be suspected in any patient with diabetes receiving metformin with evidence of acidosis but without evidence of ketoaci­dosis. Discontinue metformin in clinical situations predis­posing to hypoxemia, including conditions such as cardiovascular collapse, respiratory failure, acute myocar­dial infarction, acute congestive heart failure, and septice­mia. Use caution in patients with congestive heart failure requiring pharmacologic management, particularly in patients with unstable or acute CHF; risk of lactic acidosis may be increased secondary to hypoperfusion.
Metformin is substantially excreted by the kidney. The risk of accumulation and lactic acidosis increases with the degree of impairment of renal function. Patients with renal function below the limit of normal for their age should not receive metformin. In elderly patients, renal function should be monitored regularly; should not be initiated in patients ≥80 years of age unless normal renal function is confirmed. Use of concomitant medications that may affect renal function (ie, affect tubular secretion) may also affect met­formin disposition. Metformin should be withheld in patients with dehydration and/or prerenal azotemia. Ther­apy should be suspended for any surgical procedures (resume only after normal intake resumed and normal renal function is verified). Therapy should be temporarily discontinued prior to or at the time of intravascular admin­istration of iodinated contrast media (potential for acute alteration in renal function). Metformin should be withheld for 48 hours after the radiologic study and restarted only after renal function has been confirmed as normal. It may be necessary to discontinue metformin and administer insulin if the patient is exposed to stress (fever, trauma, infection, surgery).
Avoid use in patients with impaired liver function. Patient must be instructed to avoid excessive acute or chronic ethanol use; ethanol may potentiate metformin's effect on lactate metabolism. Administration of oral antidiabetic drugs has been reported to be associated with increased cardiovascular mortality; metformin does not appear to share this risk.

Pregnancy: Pregnancy Risk Factor: B.
Pregnancy Considerations: Adverse events have not been observed in animal studies; therefore, metformin is classified as pregnancy category B. Metformin has been found to cross the placenta in concentrations which may be comparable to those found in the maternal plasma. Pharmacokinetic studies suggest that clearance of metfor­min may be increased during pregnancy and dosing may need adjusted in some women when used during the third trimester.
Fetal, neonatal, and maternal outcomes have been eval­uated following maternal use of metformin for the treatment of GDM and type 2 diabetes. Available information suggests that metformin use during pregnancy may be safe as long as good glycemic control is maintained; however, many studies used metformin during the second or third trimester only. Maternal hyperglycemia can be associated with adverse effects in the fetus, including macrosornia, neonatal hyperglycemia, and hyperbilirubinemia; the risk of congenital malformations is increased when the HbA_1c is above the normal range. Diabetes can also be associ­ated with adverse effects in the mother. Poorly-treated diabetes may cause end-organ damage that may nega­tively affect obstetric outcomes. Physiologic glucose levels should be maintained prior to and during pregnancy to decrease the risk of adverse events in the mother and the fetus. Until additional safety and efficacy data are obtained, the use of oral agents is generally not recom­mended as routine management of GDM or type 2 dia­betes mellitus during pregnancy. Insulin is the drug of choice for the control of diabetes mellitus during preg­nancy.
Lactation: This product enters the breast milk and is not recommended for lactating women.

>10%: Gastrointestinal: Diarrhea (10% to 53%), nausea/vomit­ing (7% to 26%), flatulence (12%).
Neuromuscular and skeletal: Weakness (9%).
1%  to 10%: Cardiovascular: Chest discomfort, flushing, palpitation.
Central nervous system: Headache (6%), chills, dizziness, lightheadedness.
Dermatologic: Rash.
Endocrine and metabolic: Hypoglycemia.
Gastrointestinal: Indigestion (7%), abdominal discomfort (6%), abdominal distention, abnormal stools, constipa­tion, dyspepsia/heartburn, taste disorder.
Neuromuscular and skeletal: Myalgia.
Respiratory: Dyspnea, upper respiratory tract infection.
Miscellaneous: Decreased vitamin B₁₂ levels (7%), increased diaphoresis, flu-like syndrome, nail disorder.
<1%: (Limited to important or life-threatening): Lactic acidosis, leukocytoclastic vasculitis, megaloblastic anemia, pneumonitis.

Avoid Concomitant Use: There are no known interactions where it is recommended to avoid concomitant use.
Increased Effect/Toxicity: The levels/effects of metformin may be increased by: Cephalexin; cimetidine; iodinated contrast agents; peg­visomant.
Decreased Effect: The levels/effects of metformin may be decreased by: Corticosteroids (orally inhaled); corticosteroids (sys­temic); luteinizing hormone-releasing hormone ana­logs; somatropin; thiazide diuretics.
Ethanol/Nutrition/Herb Interactions: Ethanol: Avoid or limit ethanol (incidence of lactic acidosis may be increased; may cause hypoglycemia).
Food: Food decreases the extent and slightly delays the absorption. May decrease absorption of vitamin B₁₂ and/or folic acid.
Herb/Nutraceutical: Caution with chromium, garlic, gym­nema (may cause hypoglycemia).

Store at 20°C to 25°C (68°F to 77°F); excursion permitted to 15°C to 30°C (59°F to 86°F).
Protect from light and moisture.

Antidiabetic Agents

A10BA02 - metformin ; Belongs to the class of biguanides. Used in the treatment of diabetes.

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