Generic name: METFORMIN HYDROCHLORIDE 500mg
Dosage form: tablet, film coated, extended
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There is no fixed dosage regimen for the management of hyperglycemia in patients with type 2 diabetes with FORTAMET® or any other pharmacologic agent. Dosage of FORTAMET® must be individualized on the basis of both effectiveness and tolerance, while not exceeding the maximum recommended daily dose. The maximum recommended daily dose of FORTAMET® Extended-Release Tablets in adults is 2500 mg.
FORTAMET® should be taken with a full glass of water once daily with the evening meal. FORTAMET® should be started at a low dose, with gradual dose escalation, both to reduce gastrointestinal side effects and to permit identification of the minimum dose required for adequate glycemic control of the patient.
During treatment initiation and dose titration (see Recommended Dosing Schedule), fasting plasma glucose should be used to determine the therapeutic response to FORTAMET® and identify the minimum effective dose for the patient. Thereafter, glycosylated hemoglobin should be measured at intervals of approximately three months. The therapeutic goal should be to decrease both fasting plasma glucose and glycosylated hemoglobin levels to normal or near normal by using the lowest effective dose of FORTAMET®, either when used as monotherapy or in combination with sulfonylurea or insulin.
Monitoring of blood glucose and glycosylated hemoglobin will also permit detection of primary failure, i.e., inadequate lowering of blood glucose at the maximum recommended dose of medication, and secondary failure, i.e., loss of an adequate blood glucose lowering response after an initial period of effectiveness.
Short-term administration of FORTAMET® may be sufficient during periods of transient loss of control in patients usually well-controlled on diet alone.
Recommended Dosing Schedule
The usual starting dose of FORTAMET® (metformin hydrochloride) Extended-Release Tablets is 1000 mg taken with a full glass of water once daily with the evening meal, although 500 mg may be utilized when clinically appropriate. Dosage increases should be made in increments of 500 mg weekly, up to a maximum of 2500 mg once daily with the evening meal (see CLINICAL PHARMACOLOGY, Clinical Studies).
In randomized trials, patients currently treated with immediate-release metformin were switched to FORTAMET®. Results of this trial suggest that patients receiving immediate-release metformin treatment may be safely switched to FORTAMET® once daily at the same total daily dose, up to 2500 mg once daily. Following a switch from immediate-release metformin to FORTAMET®, glycemic control should be closely monitored and dosage adjustments made accordingly (see CLINICAL PHARMACOLOGY, Clinical Studies).
Transfer From Other Antidiabetic Therapy
When transferring patients from standard oral hypoglycemic agents other than chlorpropamide to FORTAMET®, no transition period generally is necessary. When transferring patients from chlorpropamide, care should be exercised during the first two weeks because of the prolonged retention of chlorpropamide in the body, leading to overlapping drug effects and possible hypoglycemia.
Concomitant FORTAMET® and Oral Sulfonylurea Therapy in Adult Patients
If patients have not responded to four weeks of the maximum dose of FORTAMET® monotherapy, consideration should be given to gradual addition of an oral sulfonylurea while continuing FORTAMET® at the maximum dose, even if prior primary or secondary failure to a sulfonylurea has occurred. Clinical and pharmacokinetic drug-drug interaction data are currently available only for metformin plus glyburide (also known as glibenclamide). With concomitant FORTAMET® and sulfonylurea therapy, the desired control of blood glucose may be obtained by adjusting the dose of each drug. However, attempts should be made to identify the minimum effective dose of each drug to achieve this goal. With concomitant FORTAMET® and sulfonylurea therapy, the risk of hypoglycemia associated with sulfonylurea therapy continues and may be increased. Appropriate precautions should be taken (see Package Insert of the respective sulfonylurea).
If patients have not satisfactorily responded to one to three months of concomitant therapy with the maximum dose of FORTAMET® and the maximum dose of an oral sulfonylurea, consider therapeutic alternatives including switching to insulin with or without FORTAMET®.
Concomitant FORTAMET® and Insulin Therapy in Adult Patients
The current insulin dose should be continued upon initiation of FORTAMET® therapy. FORTAMET® therapy should be initiated at 500 mg once daily in patients on insulin therapy. For patients not responding adequately, the dose of FORTAMET® should be increased by 500 mg after approximately 1 week and by 500 mg every week thereafter until adequate glycemic control is achieved. The maximum recommended daily dose for FORTAMET® Extended-Release Tablets is 2500 mg. It is recommended that the insulin dose be decreased by 10% to 25% when fasting plasma glucose concentrations decrease to less than 120 mg/dL in patients receiving concomitant insulin and FORTAMET®. Further adjustment should be individualized based on glucose-lowering response.
Specific Patient Populations
FORTAMET® is not recommended for use in pregnancy, and is not recommended in patients below the age of 17 years.
The initial and maintenance dosing of FORTAMET® should be conservative in patients with advanced age, due to the potential for decreased renal function in this population. Any dosage adjustment should be based on a careful assessment of renal function. Generally, elderly, debilitated, and malnourished patients should not be titrated to the maximum dose of FORTAMET®.
Monitoring of renal function is necessary to aid in prevention of lactic acidosis, particularly in the elderly (see WARNINGS).