GLYBURIDE

Glyburide tablets USP contain glyburide, USP, which is an oral blood-glucose-lowering drug of the sulfonylurea class. Glyburide, USP is a white or almost white, crystalline powder. The chemical name for Glyburide, USP is 1-[[p-[2-(5-chloro-o-anisamido)ethyl]phenyl]-sulfonyl]-3-cyclohexylurea. It has the following structural formula: C 23 H 28 ClN 3 O 5 S M.W. 494.0 Each glyburide tablet, USP intended for oral administration contains 1.25 mg or 2.5 mg or 5 mg of Glyburide, USP. In addition, each tablet contains the following inactive ingredients: calcium carbonate, dibasic calcium phosphate dihydrate, magnesium stearate, microcrystalline cellulose, povidone, pregelatinized starch and sodium starch glycolate. Additionally each 2.5 mg tablet contains D&C yellow # 10 aluminum lake and FD & C yellow # 6 aluminum lake; each 5 mg tablet contains D&C yellow # 10 aluminum lake and FD & C blue # 1 aluminum lake. figure

Glyburide tablets, USP are indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus.

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, i.e. , inadequate lowering of blood glucose at the maximum recommended dose of medication; and to detect secondary failure, i.e. , 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 tablets 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 tablets 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 tablets, 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 tablets. 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 tablets. 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. Patients Receiving Colesevelam When colesevelam is coadministered with glyburide, maximum plasma concentration and total exposure to glyburide is reduced. Therefore, glyburide tablets should be administered at least 4 hours prior to colesevelam. 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 ). 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 tablets 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 tablets 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 tablets 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 ). Maximum Dose Daily doses of more than 20 mg are not recommended. Dosage Interval 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 pediatric patients. 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 ).

Glyburide tablets are contraindicated in patients with: Known hypersensitivity or allergy to the drug. Diabetic ketoacidosis, with or without coma. This condition should be treated with insulin. Type I diabetes mellitus. Concomitant administration of bosentan.

Hypoglycemia: See PRECAUTIONS and OVERDOSAGE . Gastrointestinal Reactions: Cholestatic jaundice and hepatitis may occur rarely which may progress to liver failure; glyburide tablets should be discontinued if this occurs. Liver function abnormalities, including isolated transaminase elevations, have been reported. Gastrointestinal disturbances, e.g. , nausea, epigastric fullness, and heartburn are the most common reactions, having occurred in 1.8% of treated patients during clinical trials. They tend to be dose related and may disappear when dosage is reduced. Dermatologic Reactions: Allergic skin reactions, e.g. , pruritus, erythema, urticaria, and morbilliform or maculopapular eruptions occurred in 1.5% of treated patients during clinical trials. These may be transient and may disappear despite continued use of glyburide; if skin reactions persist, the drug should be discontinued. Porphyria cutanea tarda and photosensitivity reactions have been reported with sulfonylureas. Hematologic Reactions: Leukopenia, agranulocytosis, thrombocytopenia, hemolytic anemia (see PRECAUTIONS ), aplastic anemia, and pancytopenia have been reported with sulfonylureas. Metabolic Reactions: Hepatic porphyria and disulfiram-like reactions have been reported with sulfonylureas; however, hepatic porphyria has not been reported with glyburide and disulfiram-like reactions have been reported very rarely. Cases of hyponatremia have been reported with glyburide and all other sulfonylureas, most often in patients who are on other medications or have medical conditions known to cause hyponatremia or increase release of antidiuretic hormone. The syndrome of inappropriate antidiuretic hormone (SIADH) secretion has been reported with certain other sulfonylureas, and it has been suggested that these sulfonylureas may augment the peripheral (antidiuretic) action of ADH and/or increase release of ADH. Other Reactions: Changes in accommodation and/or blurred vision have been reported with glyburide and other sulfonylureas. These are thought to be related to fluctuation in glucose levels. In addition to dermatologic reactions, allergic reactions such as angioedema, arthralgia, myalgia and vasculitis have been reported.

The hypoglycemic action of sulfonylureas may be potentiated by certain drugs including non-steroidal anti-inflammatory agents and other drugs that are highly protein bound, salicylates, sulfonamides, chloramphenicol, probenecid, coumarins, monoamine oxidase inhibitors, and beta adrenergic blocking agents. When such drugs are administered to a patient receiving glyburide, the patient should be observed closely for hypoglycemia. When such drugs are withdrawn from a patient receiving glyburide, the patient should be observed closely for loss of control. An increased risk of liver enzyme elevations was observed in patients receiving glyburide concomitantly with bosentan. Therefore concomitant administration of glyburide tablets and bosentan is contraindicated. Certain drugs tend to produce hyperglycemia and may lead to loss of control. These drugs include the thiazides and other diuretics, corticosteroids, phenothiazines, thyroid products, estrogens, oral contraceptives, phenytoin, nicotinic acid, sympathomimetics, calcium channel blocking drugs, and isoniazid. When such drugs are administered to a patient receiving glyburide, the patient should be closely observed for loss of control. When such drugs are withdrawn from a patient receiving glyburide, the patient should be observed closely for hypoglycemia. A possible interaction between glyburide and ciprofloxacin, a fluoroquinolone antibiotic, has been reported, resulting in a potentiation of the hypoglycemic action of glyburide. The mechanism for this interaction is not known. A potential interaction between oral miconazole and oral hypoglycemic agents leading to severe hypoglycemia has been reported. Whether this interaction also occurs with the intravenous, topical or vaginal preparations of miconazole is not known. Metformin In a single-dose interaction study in NIDDM subjects, decreases in glyburide AUC and C max were observed, but were highly variable. The single-dose nature of this study and the lack of correlation between glyburide blood levels and pharmacodynamic effects, makes the clinical significance of this interaction uncertain. Coadministration of glyburide and metformin did not result in any changes in either metformin pharmacokinetics or pharmacodynamics. Colesevelam Concomitant administration of colesevelam and glyburide resulted in reductions in glyburide AUC and C max of 32% and 47%, respectively. The reductions in glyburide AUC and C max were 20% and 15%, respectively when administered 1 hour before, and not significantly changed (-7% and 4%, respectively) when administered 4 hours before colesevelam. Topiramate A drug-drug interaction study conducted in patients with type 2 diabetes evaluated the steady-state pharmacokinetics of glyburide (5 mg/day) alone and concomitantly with topiramate (150 mg/day). There was a 22% decrease in C max and a 25% reduction in AUC 24 for glyburide during topiramate administration. Systemic exposure (AUC) of the active metabolites, 4-trans-hydroxy-glyburide (M1) and 3-cishydroxyglyburide (M2), was also reduced by 13% and 15%, and C max was reduced by 18% and 25%, respectively. The steady-state pharmacokinetics of topiramate were unaffected by concomitant administration of glyburide.