There is no fixed dosage regimen for the management of diabetes mellitus with tolazamide 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, 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. Glycosylated hemoglobin levels may also be of value in monitoring the patient’s response to therapy.
Short-term administration of tolazamide 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 tolazamide tablets for the mild to moderately severe type II diabetic patient is 100 mg to 250 mg daily administered with breakfast or the first main meal. Generally, if the fasting blood glucose is less than 200 mg/dL the starting dose is 100 mg/day as a single daily dose. If the fasting blood glucose value is greater than 200 mg/dL, the starting dose is 250 mg/day as a single dose. If the patient is malnourished, underweight, elderly, or not eating properly, the initial therapy should be 100 mg once a day. Failure to follow an appropriate dosage regimen may precipitate hypoglycemia. Patients who do not adhere to their prescribed dietary regimen are more prone to exhibit unsatisfactory response to drug therapy.
Transfer from other Hypoglycemic Therapy
Patients Receiving Other Oral Antidiabetic Therapy
Transfer of patients from other oral antidiabetes regimens to tolazamide should be done conservatively. When transferring patients from oral hypoglycemic agents other than chlorpropamide to tolazamide, no transition period or initial or priming dose is necessary. When transferring from chlorpropamide, particular care should be exercised to avoid hypoglycemia.
Tolbutamide
If receiving less than 1 gm/day, begin at 100 mg of tolazamide per day. If receiving 1 gm or more per day, initiate at 250 mg of tolazamide per day as a single dose.
Chlorpropamide
250 mg of chlorpropamide may be considered to provide approximately the same degree of blood glucose control as 250 mg of tolazamide. The patient should be observed carefully for hypoglycemia during the transition period from chlorpropamide to tolazamide (1 to 2 weeks) due to the prolonged retention of chlorpropamide in the body and the possibility of a subsequent overlapping drug effect.
Acetohexamide
100 mg of tolazamide may be considered to provide approximately the same degree of blood glucose control as 250 mg of acetohexamide.
Patients Receiving Insulin
Some type II diabetic patients who have been treated only with insulin may respond satisfactorily to therapy with tolazamide. If the patient’s previous insulin dosage has been less than 20 units, substitution of 100 mg of tolazamide per day as a single daily dose may be tried. If the previous insulin dosage was less than 40 units, but more than 20 units, the patient should be placed directly on 250 mg of tolazamide per day as a single dose. If the previous insulin dosage was greater than 40 units, the insulin dosage should be decreased by 50% and 250 mg of tolazamide per day started. The dosage of tolazamide should be adjusted weekly (or more often in the group previously requiring more than 40 units of insulin).
During this conversion period when both insulin and tolazamide are being used, hypoglycemia may rarely occur. During insulin withdrawal, patients should test their urine for glucose and acetone at least 3 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.
Maximum Dose
Daily doses of greater than 1000 mg are not recommended. Patients will generally have no further response to doses larger than this.
Usual Maintenance Dose
The usual maintenance dose is in the range of 100 to 1000 mg/day with the average maintenance dose being 250 to 500 mg/day. Following initiation of therapy, dosage adjustment is made in increments of 100 mg to 250 mg at weekly intervals based on the patient’s blood glucose response.
Dosage Interval
Once a day therapy is usually satisfactory. Doses up to 500 mg/day should be given as a single dose in the morning. 500 mg once daily is as effective as 250 mg twice daily. When a dose of more than 500 mg/day is required, the dose may be divided and given twice daily.
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).
