DOSAGE AND ADMINISTRATION
Patients should be retitrated when transferred from glyburide (micronized) tablets or other oral hypoglycemic agents. (See PRECAUTIONS).
There is no fixed dosage regimen for the management of diabetes mellitus with glyburide tablets or any other hypoglycemic agent. In addition to the usual monitoring of urinary glucose, the patient’s blood glucose must also be monitored periodically to determine the minimum effective dose for the patient; to detect primary failure, ie, inadequate lowering of blood glucose at the maximum recommended dose of medication; and to detect secondary failure, ie, loss of adequate blood glucose lowering response after an initial period of effectiveness. Glycosylated hemoglobin levels may also be of value in monitoring the patient’s response to therapy.
Short-term administration of glyburide may be sufficient during periods of transient loss of control in patients usually controlled well on diet.
Usual Starting Dose
The usual starting dose of glyburide tablets is 2.5 to 5 mg daily, administered with breakfast or the first main meal. Those patients who may be more sensitive to hypoglycemic drugs should be started at 1.25 mg daily. (See PRECAUTIONS section for patients at increased risk.) Failure to follow an appropriate dosage regimen may precipitate hypoglycemia. Patients who do not adhere to their prescribed dietary and drug regimen are more prone to exhibit unsatisfactory response to therapy.
Transfer From Other Hypoglycemic Therapy Patients Receiving Other Oral Antidiabetic Therapy
Transfer of patients from other oral antidiabetic regimens to glyburide should be done conservatively and the initial daily dose should be 2.5 to 5 mg. When transferring patients from oral hypoglycemic agents other than chlorpropamide to glyburide, no transition period and no initial or priming dose are necessary. When transferring patients from chlorpropamide, particular care should be exercised during the first two weeks because the prolonged retention of chlorpropamide in the body and subsequent overlapping drug effects may provoke hypoglycemia.
Patients Receiving Insulin
Some Type II diabetic patients being treated with insulin may respond satisfactorily to glyburide. If the insulin dose is less than 20 units daily, substitution of glyburide tablets 2.5 to 5 mg as a single daily dose may be tried. If the insulin dose is between 20 and 40 units daily, the patient may be placed directly on glyburide tablets 5 mg daily as a single dose. If the insulin dose is more than 40 units daily, a transition period is required for conversion to glyburide. In these patients, insulin dosage is decreased by 50% and glyburide tablets 5 mg daily is started. Please refer to Titration to Maintenance Dose for further explanation.
Titration to Maintenance Dose
The usual maintenance dose is in the range of 1.25 to 20 mg daily, which may be given as a single dose or in divided doses (See Dosage Interval Section). Dosage increases should be made in increments of no more than 2.5 mg at weekly intervals based upon the patient’s blood glucose response.
No exact dosage relationship exists between glyburide and the other oral hypoglycemic agents. Although patients may be transferred from the maximum dose of other sulfonylureas, the maximum starting dose of 5 mg of glyburide tablets should be observed. A maintenance dose of 5 mg of glyburide tablets provides approximately the same degree of blood glucose control as 250 to 375 mg chlorpropamide, 250 to 375 mg tolazamide, 500 to 750 mg acetohexamide, or 1000 to 1500 mg tolbutamide.
When transferring patients receiving more than 40 units of insulin daily, they may be started on a daily dose of glyburide tablets 5 mg concomitantly with a 50% reduction in insulin dose. Progressive withdrawal of insulin and increase of glyburide in increments of 1.25 to 2.5 mg every 2 to 10 days is then carried out. During this conversion period when both insulin and glyburide are being used, hypoglycemia may rarely occur. During insulin withdrawal, patients should test their urine for glucose and acetone at least three times daily and report results to their physician. The appearance of persistent acetonuria with glycosuria indicates that the patient is a Type I diabetic who requires insulin therapy.
Concomitant Glyburide and Metformin Therapy
Glyburide tablets should be added gradually to the dosing regimen of patients who have not responded to the maximum dose of metformin monotherapy after four weeks (see Usual Starting Dose and Titration to Maintenance Dose). Refer to metformin package insert.
With concomitant glyburide and metformin 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 optimal dose of each drug needed to achieve this goal. With concomitant glyburide and metformin therapy, the risk of hypoglycemia associated with sulfonylurea therapy continues and may be increased. Appropriate precautions should be taken (see PRECAUTIONS section).
Daily doses of more than 20 mg are not recommended.
Once-a-day therapy is usually satisfactory. Some patients, particularly those receiving more than 10 mg daily, may have a more satisfactory response with twice-a-day dosage.
Specific Patient Populations
Glyburide is not recommended for use in pregnancy or for use in children.
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.)