The usual starting dose of Glipizide XL 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 XL 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 XL 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 XL 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 XL 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 XL extended-release tablets once-a-day at the nearest equivalent total daily dose. Patients receiving immediate release glipizide tablets also may be titrated to the appropriate dose of Glipizide XL 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).