DOSAGE AND ADMINISTRATION
There is no fixed dosage regimen for the management of diabetes mellitus with glipizide extended-release tablets or any other hypoglycemic agent. Glycemic control should be monitored with hemoglobin A1C and/or blood-glucose levels to determine the minimum effective dose for the patient; to detect primary failure, i.e., inadequate lowering of blood glucose at the maximum recommended dose of medication; and to detect secondary failure, i.e., loss of an adequate blood-glucose-lowering response after an initial period of effectiveness. Home blood-glucose monitoring may also provide useful information to the patient and physician. Short-term administration of glipizide extended-release tablets may be sufficient during periods of transient loss of control in patients usually controlled on diet.
In general, glipizide extended-release tablets should be given with breakfast.
Recommended Dosing: The usual starting dose of glipizide extended-release tablets as initial therapy is 5 mg per day, given with breakfast. Those patients who may be more sensitive to hypoglycemic drugs may be started at a lower dose.
Dosage adjustment should be based on laboratory measures of glycemic control. While fasting blood-glucose levels generally reach steady-state following initiation or change in glipizide dosage, a single fasting glucose determination may not accurately reflect the response to therapy. In most cases, hemoglobin A1C level measured at three month intervals is the preferred means of monitoring response to therapy.
Hemoglobin A1C should be measured as glipizide therapy is initiated and repeated approximately three months later. If the result of this test suggests that glycemic control over the preceding three months was inadequate, the glipizide dose may be increased. Subsequent dosage adjustments should be made on the basis of hemoglobin A1C levels measured at three month intervals. If no improvement is seen after three months of therapy with a higher dose, the previous dose should be resumed. Decisions which utilize fasting blood glucose to adjust glipizide therapy should be based on at least two or more similar, consecutive values obtained seven days or more after the previous dose adjustment.
Most patients will be controlled with 5 mg to 10 mg taken once daily. However, some patients may require up to the maximum recommended daily dose of 20 mg. While the glycemic control of selected patients may improve with doses which exceed 10 mg, clinical studies conducted to date have not demonstrated an additional group average reduction of hemoglobin A1C beyond what was achieved with the 10 mg dose.
Based on the results of a randomized crossover study, patients receiving immediate release glipizide may be switched safely to glipizide extended-release tablets once-a-day at the nearest equivalent total daily dose. Patients receiving immediate release glipizide also may be titrated to the appropriate dose of glipizide extended-release tablets starting with 5 mg once daily. The decision to switch to the nearest equivalent dose or to titrate should be based on clinical judgment.
In elderly patients, debilitated or malnourished patients, and patients with impaired renal or hepatic function, the initial and maintenance dosing should be conservative to avoid hypoglycemic reactions (see PRECAUTIONS section).
Combination Use: When adding other blood-glucose-lowering agents to glipizide for combination therapy, the agent should be initiated at the lowest recommended dose, and patients should be observed carefully for hypoglycemia. Refer to the product information supplied with the oral agent for additional information.
When adding glipizide to other blood-glucose-lowering agents, glipizide extended-release tablets can be initiated at 5 mg. Those patients who may be more sensitive to hypoglycemic drugs may be started at a lower dose. Titration should be based on clinical judgment.
Patients Receiving Insulin: As with other sulfonylurea-class hypoglycemics, many patients with stable type 2 diabetes receiving insulin may be transferred safely to treatment with glipizide extended-release tablets. When transferring patients from insulin to glipizide, the following general guidelines should be considered:
For patients whose daily insulin requirement is 20 units or less, insulin may be discontinued and glipizide therapy may begin at usual dosages. Several days should elapse between titration steps.
For patients whose daily insulin requirement is greater than 20 units, the insulin dose should be reduced by 50% and glipizide therapy may begin at usual dosages. Subsequent reductions in insulin dosage should depend on individual patient response. Several days should elapse between titration steps.
During the insulin withdrawal period, the patient should test urine samples for sugar and ketone bodies at least three times daily. Patients should be instructed to contact the prescriber immediately if these tests are abnormal. In some cases, especially when the patient has been receiving greater than 40 units of insulin daily, it may be advisable to consider hospitalization during the transition period.
Patients Receiving Other Oral Hypoglycemic Agents: As with other sulfonylurea-class hypoglycemics, no transition period is necessary when transferring patients to glipizide extended-release tablets. Patients should be observed carefully (1-2 weeks) for hypoglycemia when being transferred from longer half-life sulfonylureas (e.g., chlorpropamide) to glipizide due to potential overlapping of drug effect.
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