Glipizide; Metformin Hydrochloride 003575

Categories, Drug Classes, Brand Names & Cost Of Therapy

Categories: Pregnancy Category C; FDA Approved 2002 Oct

Brand Names: Metaglip

Description

Metaglip (glipizide; metformin hydrochloride) tablets contains 2 oral antihyperglycemic drugs used in the management of Type 2 diabetes, glipizide and metformin hydrochloride.

Glipizide is an oral antihyperglycemic drug of the sulfonylurea class. The chemical name for glipizide is 1-cyclohexyl-3-[[p -[2-(5-methylpyrazinecarboxamido)ethyl]phenyl]sulfonyl]urea. Glipizide is a whitish, odorless powder with a molecular formula of C ₂₁ H ₂₇ N ₅ O ₄ S, a molecular weight of 445.55 and a pK _a of 5.9. It is insoluble in water and alcohols, but soluble in 0.1 N NaOH; it is freely soluble in dimethylformamide.

Metformin hydrochloride is an oral antihyperglycemic drug used in the management of Type 2 diabetes. Metformin hydrochloride (N,N -dimethylimidodicarbonimidic diamide mono-hydrochloride) is not chemically or pharmacologically related to sulfonylureas, thiazolidinediones, or a-glucosidase inhibitors. It is a white to off-white crystalline compound with a molecular formula of C ₄ H ₁₂ ClN ₅ (mono-hydrochloride) and a molecular weight of 165.63. Metformin hydrochloride is freely soluble in water and is practically insoluble in acetone, ether, and chloroform. The pK _a of metformin is 12.4. The pH of a 1% aqueous solution of metformin hydrochloride is 6.68.

Metaglip is available for oral administration in tablets containing 2.5 mg glipizide with 250 mg metformin hydrochloride, 2.5 mg glipizide with 500 mg metformin hydrochloride, and 5 mg glipizide with 500 mg metformin hydrochloride. In addition, each tablet contains the following inactive ingredients: microcrystalline cellulose, povidone, croscarmellose sodium, and magnesium stearate. The tablets are film coated, which provides color differentiation.

Clinical Pharmacology

Metaglip combines glipizide and metformin HCl, two antihyperglycemic agents with complementary mechanisms of action, to improve glycemic control in patients with Type 2 diabetes.

Glipizide appears to lower blood glucose acutely by stimulating the release of insulin from the pancreas, an effect dependent upon functioning beta cells in the pancreatic islets. Extrapancreatic effects may play a part in the mechanism of action of oral sulfonylurea hypoglycemic drugs. The mechanism by which glipizide lowers blood glucose during long-term administration has not been clearly established. In man, stimulation of insulin secretion by glipizide in response to a meal is undoubtedly of major importance. Fasting insulin levels are not elevated even on long-term glipizide administration, but the postprandial insulin response continues to be enhanced after at least 6 months of treatment.

Metformin HCl is an antihyperglycemic agent that improves glucose tolerance in patients with Type 2 diabetes, lowering both basal and postprandial plasma glucose. Metformin HCl decreases hepatic glucose production, decreases intestinal absorption of glucose, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization.

Pharmacokinetics

Absorbtion and Bioavailability

Metaglip

In a single dose study in healthy subjects, the glipizide and metformin components of Metaglip 5 mg/500 mg were bioequivalent to coadministered Glucotrol and Glucophage. Following administration of a single Metaglip 5 mg/500 mg tablet in healthy subjects with either a 20% glucose solution or a 20% glucose solution with food, there was a small effect of food on peak plasma concentration (C_max) and no effect of food on area under the curve (AUC) of the glipizide component. Time to peak plasma concentration (T_max) for the glipizide component was delayed 1 hour with food relative to the same tablet strength administered fasting with a 20% glucose solution. C_max for the metformin component was reduced approximately 14% by food whereas AUC was not affected. T_max for the metformin component was delayed 1 hour after food.

Glipizide

Gastrointestinal absorption of glipizide is uniform, rapid, and essentially complete. Peak plasma concentrations occur 1-3 hours after a single oral dose. Glipizide does not accumulate in plasma on repeated oral administration. Total absorption and disposition of an oral dose was unaffected by food in normal volunteers, but absorption was delayed by about 40 minutes.

Metformin HCl

The absolute bioavailability of a 500 mg metformin HCl tablet given under fasting conditions is approximately 50-60%. Studies using single oral doses of metformin tablets of 500 and 1500 mg, and 850-2550 mg, indicate that there is a lack of dose proportionality with increasing doses, which is due to decreased absorption rather than an alteration in elimination. Food decreases the extent of and slightly delays the absorption of metformin, as shown by approximately a 40% lower peak concentration and a 25% lower AUC in plasma and a 35 minute prolongation of time to peak plasma concentration following administration of a single 850 mg tablet of metformin with food, compared to the same tablet strength administered fasting. The clinical relevance of these decreases is unknown.

Distribution

Glipizide

Protein binding was studied in serum from volunteers who received either oral or intravenous glipizide and found to be 98-99% one hour after either route of administration. The apparent volume of distribution of glipizide after intravenous administration was 11 L, indicative of localization within the extracellular fluid compartment. In mice, no glipizide or metabolites were detectable autoradiographically in the brain or spinal cord of males or females, nor in the fetuses of pregnant females. In another study, however, very small amounts of radioactivity were detected in the fetuses of rats given labeled drug.

Metformin HCl

The apparent volume of distribution (V/F) of metformin following single oral doses of 850 mg veraged 654 ± 358 L. Metformin is negligibly bound to plasma proteins. Metformin partitions into erythrocytes, most likely as a function of time. At usual clinical doses and dosing schedules of metformin, steady state plasma concentrations of metformin are reached within 24-48 hours and are generally <1 µg/ml. During controlled clinical trials, maximum metformin plasma levels did not exceed 5 µg/ml, even at maximum doses.

Metabolism and Elimination

Glipizide

The metabolism of glipizide is extensive and occurs mainly in the liver. The primary metabolites are inactive hydroxylation products and polar conjugates and are excreted mainly in the urine. Less than 10% unchanged glipizide is found in the urine. The half-life of elimination ranges from 2-4 hours in normal subjects, whether given intravenously or orally. The metabolic and excretory patterns are similar with the 2 routes of administration, indicating that first-pass metabolism is not significant.

Metformin HCl

Intravenous single-dose studies in normal subjects demonstrate that metformin is excreted unchanged in the urine and does not undergo hepatic metabolism (no metabolites have been identified in humans) nor biliary excretion. Renal clearance (see TABLE 1) is approximately 3.5 times greater than creatinine clearance, which indicates that tubular secretion is the major route of metformin elimination. Following oral administration, approximately 90% of the absorbed drug is eliminated via the renal route within the first 24 hours, with a plasma elimination half-life of approximately 6.2 hours. In blood, the elimination half-life is approximately 17.6 hours, suggesting that the erythrocyte mass may be a compartment of distribution.

Special Populations

Patients With Type 2 Diabetes

In the presence of normal renal function, there are no differences between single- or multiple-dose pharmacokinetics of metformin between patients with Type 2 diabetes and normal subjects (see TABLE 1), nor is there any accumulation of metformin in either group at usual clinical doses.

Hepatic Insufficiency

The metabolism and excretion of glipizide may be slowed in patients with impaired hepatic function (see PRECAUTIONS). No pharmacokinetic studies have been conducted in patients with hepatic insufficiency for metformin.

Renal Insufficiency

The metabolism and excretion of glipizide may be slowed in patients with impaired renal function (see PRECAUTIONS).

In patients with decreased renal function (based on creatinine clearance), the plasma and blood half-life of metformin is prolonged and the renal clearance is decreased in proportion to the decrease in creatinine clearance (see TABLE 1; also, see WARNINGS).

Geriatrics

There is no information on the pharmacokinetics of glipizide in elderly patients.

Limited data from controlled pharmacokinetic studies of metformin in healthy elderly subjects suggest that total plasma clearance is decreased, the half-life is prolonged, and C_max is increased, compared to healthy young subjects. From these data, it appears that the change in metformin pharmacokinetics with aging is primarily accounted for by a change in renal function (see TABLE 1). Metformin treatment should not be initiated in patients ≥80 years of age unless measurement of creatinine clearance demonstrates that renal function is not reduced.

Pediatrics

No data from pharmacokinetic studies in pediatric subjects are available for either glipizide or metformin.

Gender

There is no information on the effect of gender on the pharmacokinetics of glipizide.

Metformin pharmacokinetic parameters did not differ significantly in subjects with or without Type 2 diabetes when analyzed according to gender (males = 19, females = 16). Similarly, in controlled clinical studies in patients with Type 2 diabetes, the antihyperglycemic effect of metformin was comparable in males and females.

Race

No information is available on race differences in the pharmacokinetics of glipizide.

No studies of metformin pharmacokinetic parameters according to race have been performed. In controlled clinical studies of metformin in patients with Type 2 diabetes, the antihyperglycemic effect was comparable in whites (n=249), blacks (n=51), and Hispanics (n=24).

Clinical Studies

In a 24 week, double-blind, active-controlled, multicenter international clinical trial, patients with Type 2 diabetes, whose hyperglycemia was not adequately controlled with diet and exercise alone (hemoglobin A_1c [HbA_1c] >7.5% and ≤12% and fasting plasma glucose [FPG] <300 mg/dl) were randomized to receive initial therapy with glipizide 5 mg, metformin 500 mg, Metaglip 2.5 mg/250 mg, or Metaglip 2.5 mg/500 mg. After 2 weeks, the dose was progressively increased (up to the 12 week visit) to a maximum of 4 tablets daily in divided doses as needed to reach a target mean daily glucose (MDG) of ≤130 mg/dl. Trial data at 24 weeks are summarized in TABLE 2.

After 24 weeks, treatment with Metaglip (glipizide; metformin HCl) tablets 2.5 mg/250 mg and 2.5 mg/500 mg resulted in significantly greater reduction in HbA_1c compared to glipizide and to metformin therapy. Also, Metaglip 2.5 mg/250 mg therapy resulted in significant reductions in FPG versus metformin therapy.

Increases above fasting glucose and insulin levels were determined at baseline and final study visits by measurement of plasma glucose and insulin for 3 hours following a standard mixed liquid meal. Treatment with Metaglip lowered the 3 hour postprandial glucose AUC, compared to baseline, to a significantly greater extent than did the glipizide and the metformin therapies. Compared to baseline, Metaglip enhanced the postprandial insulin response, but did not significantly affect fasting insulin levels.

There were no clinically meaningful differences in changes from baseline for all lipid parameters between Metaglip therapy and either metformin therapy or glipizide therapy. The adjusted mean changes from baseline in body weight were: Metaglip 2.5 mg/250 mg, -0.4 kg; Metaglip 2.5 mg/500 mg, -0.5 kg; glipizide, -0.2 kg; and metformin, -1.9 kg. Weight loss was greater with metformin than with Metaglip.

Second-Line Therapy

In an 18 week, double-blind, active-controlled US clinical trial, a total of 247 patients with Type 2 diabetes not adequately controlled (HbA_1c ≥7.5% and ≤12% and FPG <300 mg/dl) while being treated with at least one-half the maximum labeled dose of a sulfonylurea (e.g., glyburide 10 mg, glipizide 20 mg) were randomized to receive glipizide (fixed dose, 30 mg), metformin (500 mg), or Metaglip 5 mg/500 mg. The doses of metformin and Metaglip were titrated (up to the 8 week visit) to a maximum of 4 tablets daily as needed to achieve MDG ≤130 mg/dl. Trial data at 18 weeks are summarized in TABLE 3.

After 18 weeks, treatment with Metaglip at doses up to 20 mg/2000 mg/day resulted in significantly lower mean final HbA_1c and significantly greater mean reductions in FPG compared to glipizide and to metformin therapy. Treatment with Metaglip lowered the 3 hour postprandial glucose AUC, compared to baseline, to a significantly greater extent than did the glipizide and the metformin therapies. Metaglip did not significantly affect fasting insulin levels.

There were no clinically meaningful differences in changes from baseline for all lipid parameters between Metaglip therapy and either metformin therapy or glipizide therapy. The adjusted mean changes from baseline in body weight were: Metaglip 5 mg/500 mg, -0.3 kg; glipizide, -0.4 kg; and metformin, -2.7 kg. Weight loss was greater with metformin than with Metaglip.

Indications And Usage

Metaglip is indicated as second-line therapy when diet, exercise, and initial treatment with a sulfonylurea or metformin do not result in adequate glycemic control in patients with Type 2 diabetes.

Contraindications

Metaglip should be temporarily discontinued in patients undergoing radiologic studies involving intravascular administration of iodinated contrast materials, because use of such products may result in acute alteration of renal function. (See also PRECAUTIONS.)

Warnings

SPECIAL WARNING ON INCREASED RISK OF CARDIOVASCULAR MORTALITY

The administration of oral hypoglycemic drugs has been reported to be associated with increased cardiovascular mortality as compared to treatment with diet alone or diet plus insulin. This warning is based on the study conducted by the University Group Diabetes Program (UGDP), a long-term prospective clinical trial designed to evaluate the effectiveness of glucose-lowering drugs in preventing or delaying vascular complications in patients with non-insulin-dependent diabetes. The study involved 823 patients who were randomly assigned to 1 of 4 treatment groups (Diabetes 19 (Suppl. 2):747-830, 1970).

UGDP reported that patients treated for 5-8 years with diet plus a fixed dose of tolbutamide (1.5 g/day) had a rate of cardiovascular mortality approximately 2½ times that of patients treated with diet alone. A significant increase in total mortality was not observed, but the use of tolbutamide was discontinued based on the increase in cardiovascular mortality, thus limiting the opportunity for the study to show an increase in overall mortality. Despite controversy regarding the interpretation of these results, the findings of the UGDP study provide an adequate basis for this warning. The patient should be informed of the potential risks and benefits of glipizide and of alternative modes of therapy.

Although only one drug in the sulfonylurea class (tolbutamide) was included in this study, it is prudent from a safety standpoint to consider that this warning may also apply to other hypoglycemic drugs in this class, in view of their close similarities in mode of action and chemical structure.

Precautions

Metaglip

Hypoglycemia

Metaglip (glipizide; metformin HCl) tablets is capable of producing hypoglycemia, therefore, proper patient selection, dosing, and instructions are important to avoid potential hypoglycemic episodes. The risk of hypoglycemia is increased when caloric intake is deficient, when strenuous exercise is not compensated by caloric supplementation, or during concomitant use with other glucose-lowering agents or ethanol. Renal insufficiency may cause elevated drug levels of both glipizide and metformin HCl. Hepatic insufficiency may increase drug levels of glipizide and may also diminish gluconeogenic capacity, both of which increase the risk of hypoglycemic reactions. Elderly, debilitated, or malnourished patients and those with adrenal or pituitary insufficiency or alcohol intoxication are particularly susceptible to hypoglycemic effects. Hypoglycemia may be difficult to recognize in the elderly, and in people who are taking beta-adrenergic blocking drugs.

Glipizide

Renal and Hepatic Disease

The metabolism and excretion of glipizide may be slowed in patients with impaired renal and/or hepatic function. If hypoglycemia should occur in such patients, it may be prolonged and appropriate management should be instituted.

Metformin HCl

Monitoring of Renal Function

Metformin is known to be substantially excreted by the kidney, and the risk of metformin accumulation and lactic acidosis increases with the degree of impairment of renal function. Thus, patients with serum creatinine levels above the upper limit of normal for their age should not receive Metaglip. In patients with advanced age, Metaglip should be carefully titrated to establish the minimum dose for adequate glycemic effect, because aging is associated with reduced renal function. In elderly patients, particularly those ≥80 years of age, renal function should be monitored regularly and, generally, Metaglip should not be titrated to the maximum dose (see WARNINGS and DOSAGE AND ADMINISTRATION). Before initiation of Metaglip therapy and at least annually thereafter, renal function should be assessed and verified as normal. In patients in whom development of renal dysfunction is anticipated, renal function should be assessed more frequently and Metaglip discontinued if evidence of renal impairment is present.

Use of Concomitant Medications That may Affect Renal Function or Metformin Disposition

Concomitant medication(s) that may affect renal function or result in significant hemodynamic change or may interfere with the disposition of metformin, such as cationic drugs that are eliminated by renal tubular secretion (see DRUG INTERACTIONS), should be used with caution.

Radiologic Studies Involving the use of Intravascular Iodinated Contrast Materials (for example, IV urogram, IV cholangiography, angiography, and computed tomography (ct) scans with intravascular contrast materials)

Intravascular contrast studies with iodinated materials can lead to acute alteration of renal function and have been associated with lactic acidosis in patients receiving metformin (see CONTRAINDICATIONS). Therefore, in patients in whom any such study is planned, Metaglip should be temporarily discontinued at the time of or prior to the procedure, and withheld for 48 hours subsequent to the procedure and reinstituted only after renal function has been reevaluated and found to be normal.

Hypoxic States

Cardiovascular collapse (shock) from whatever cause, acute congestive heart failure, acute myocardial infarction, and other conditions characterized by hypoxemia have been associated with lactic acidosis and may also cause prerenal azotemia. When such events occur in patients on Metaglip therapy, the drug should be promptly discontinued.

Surgical Procedures

Metaglip therapy should be temporarily suspended for any surgical procedure (except minor procedures not associated with restricted intake of food and fluids) and should not be restarted until the patient’s oral intake has resumed and renal function has been evaluated as normal.

Alcohol Intake

Alcohol is known to potentiate the effect of metformin on lactate metabolism. Patients, therefore, should be warned against excessive alcohol intake, acute or chronic, while receiving Metaglip. Due to its effect on the gluconeogenic capacity of the liver, alcohol may also increase the risk of hypoglycemia.

Impaired Hepatic Function

Since impaired hepatic function has been associated with some cases of lactic acidosis, Metaglip should generally be avoided in patients with clinical or laboratory evidence of hepatic disease.

Vitamin B₁₂ Level

In controlled clinical trials with metformin of 29 weeks duration, a decrease to subnormal levels of previously normal serum vitamin B₁₂, without clinical manifestations, was observed in approximately 7% of patients. Such decrease, possibly due to interference with B₁₂ absorption from the B₁₂-intrinsic factor complex, is, however, very rarely associated with anemia and appears to be rapidly reversible with discontinuation of metformin or vitamin B₁₂ supplementation. Measurement of hematologic parameters on an annual basis is advised in patients on metformin and any apparent abnormalities should be appropriately investigated and managed (see Laboratory Tests).

Certain individuals (those with inadequate vitamin B₁₂ or calcium intake or absorption) appear to be predisposed to developing subnormal vitamin B₁₂ levels. In these patients, routine serum vitamin B₁₂ measurements at 2-3 year intervals may be useful.

Change in Clinical Status of Patients With Previously Controlled Type 2 Diabetes

A patient with Type 2 diabetes previously well-controlled on metformin who develops laboratory abnormalities or clinical illness (especially vague and poorly defined illness) should be evaluated promptly for evidence of ketoacidosis or lactic acidosis. Evaluation should include serum electrolytes and ketones, blood glucose and, if indicated, blood pH, lactate, pyruvate, and metformin levels. If acidosis of either form occurs, Metaglip (glipizide; metformin HCl) tablets must be stopped immediately and other appropriate corrective measures initiated (see also WARNINGS).

Information for the Patient

Metaglip

Patients should be informed of the potential risks and benefits of Metaglip and of alternative modes of therapy. They should also be informed about the importance of adherence to dietary instructions, of a regular exercise program, and of regular testing of blood glucose, glycosylated hemoglobin, renal function, and hematologic parameters.

The risks of lactic acidosis associated with metformin therapy, its symptoms, and conditions that predispose to its development, as noted in WARNINGS and PRECAUTIONS, should be explained to patients. Patients should be advised to discontinue Metaglip immediately and to promptly notify their health practitioner if unexplained hyperventilation, myalgia, malaise, unusual somnolence, or other nonspecific symptoms occur. Once a patient is stabilized on any dose level of Metaglip, gastrointestinal symptoms, which are common during initiation of metformin therapy, are unlikely to be drug related. Later occurrence of gastrointestinal symptoms could be due to lactic acidosis or other serious disease.

The risks of hypoglycemia, its symptoms and treatment, and conditions that predispose to its development should be explained to patients and responsible family members.

Patients should be counseled against excessive alcohol intake, either acute or chronic, while receiving Metaglip. (See Patient Information distributed with the prescription.)

Laboratory Tests

Periodic fasting blood glucose and glycosylated hemoglobin (HbA_1c) measurements should be performed to monitor therapeutic response.

Initial and periodic monitoring of hematologic parameters (e.g., hemoglobin/hematocrit and red blood cell indices) and renal function (serum creatinine) should be performed, at least on an annual basis. While megaloblastic anemia has rarely been seen with metformin therapy, if this is suspected, vitamin B ₁₂ deficiency should be excluded.

Carcinogenesis, Mutagenesis, and Impairment of Fertility

No animal studies have been conducted with the combined products in Metaglip. The following data are based on findings in studies performed with the individual products.

Glipizide

A 20 month study in rats and an 18 month study in mice at doses up to 75 times the maximum human dose revealed no evidence of drug-related carcinogenicity. Bacterial and in vivo mutagenicity tests were uniformly negative. Studies in rats of both sexes at doses up to 75 times the human dose showed no effects on fertility.

Metformin HCl

Long-term carcinogenicity studies were performed with metformin alone in rats (dosing duration of 104 weeks) and mice (dosing duration of 91 weeks) at doses up to and including 900 mg/kg/day and 1500 mg/kg/day, respectively. These doses are both approximately 4 times the maximum recommended human daily dose of 2000 mg of the metformin component of Metaglip based on body surface area comparisons. No evidence of carcinogenicity with metformin alone was found in either male or female mice. Similarly, there was no tumorigenic potential observed with metformin alone in male rats. There was, however, an increased incidence of benign stromal uterine polyps in female rats treated with 900 mg/kg/day of metformin alone.

There was no evidence of a mutagenic potential of metformin alone in the following in vitro tests: Ames test ( S. typhimurium ), gene mutation test (mouse lymphoma cells), or chromosomal aberrations test (human lymphocytes). Results in the in vitro mouse micronucleus test were also negative.

Fertility of male or female rats was unaffected by metformin alone when administered at doses as high as 600 mg/kg/day, which is approximately 3 times the maximum recommended human daily dose of the metformin component of Metaglip based on body surface area comparisons.

Pregnancy Category C

Teratogenic Effects

Recent information strongly suggests that abnormal blood glucose levels during pregnancy are associated with a higher incidence of congenital abnormalities. Most experts recommend that insulin be used during pregnancy to maintain blood glucose as close to normal as possible. Because animal reproduction studies are not always predictive of human response, Metaglip should not be used during pregnancy unless clearly needed. (See Nonteratogenic Effects.)

There are no adequate and well-controlled studies in pregnant women with Metaglip or its individual components. No animal studies have been conducted with the combined products in Metaglip. The following data are based on findings in studies performed with the individual products.

Glipizide

Glipizide was found to be mildly fetotoxic in rat reproductive studies at all dose levels (5-50 mg/kg). This fetotoxicity has been similarly noted with other sulfonylureas, such as tolbutamide and tolazamide. The effect is perinatal and believed to be directly related to the pharmacologic (hypoglycemic) action of glipizide. In studies in rats and rabbits, no teratogenic effects were found.

Metformin HCl

Metformin alone was not teratogenic in rats or rabbits at doses up to 600 mg/kg/day. This represents an exposure of about 2 and 6 times the maximum recommended human daily dose of 2000 mg of the metformin component of Metaglip based on body surface area comparisons for rats and rabbits, respectively. Determination of fetal concentrations demonstrated a partial placental barrier to metformin.

Nonteratogenic Effects

Prolonged severe hypoglycemia (4-10 days) has been reported in neonates born to mothers who were receiving a sulfonylurea drug at the time of delivery. This has been reported more frequently with the use of agents with prolonged half-lives. It is not recommended that Metaglip be used during pregnancy. However, if it is used, Metaglip should be discontinued at least 1 month before the expected delivery date. (See Teratogenic Effects.)

Nursing Mothers

Although it is not known whether glipizide is excreted in human milk, some sulfonylurea drugs are known to be excreted in human milk. Studies in lactating rats show that metformin is excreted into milk and reaches levels comparable to those in plasma. Similar studies have not been conducted in nursing mothers. Because the potential for hypoglycemia in nursing infants may exist, a decision should be made whether to discontinue nursing or to discontinue Metaglip, taking into account the importance of the drug to the mother. If Metaglip is discontinued, and if diet alone is inadequate for controlling blood glucose, insulin therapy should be considered.

Pediatric Use

Safety and effectiveness of Metaglip in pediatric patients have not been established.

Geriatric Use

Of the 345 patients who received Metaglip 2.5 mg/250 mg and 2.5 mg/500 mg in the initial therapy trial, 67 (19.4%) were aged 65 and older while 5 (1.4%) were aged 75 and older. Of the 87 patients who received Metaglip in the second-line therapy trial, 17 (19.5%) were aged 65 and older while 1 (1.1%) was at least aged 75. No overall differences in effectiveness or safety were observed between these patients and younger patients in either the initial therapy trial or the second-line therapy trial, and other reported clinical experience has not identified differences in response between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.

Metformin HCl is known to be substantially excreted by the kidney and because the risk of serious adverse reactions to the drug is greater in patients with impaired renal function, Metaglip should only be used in patients with normal renal function (see CONTRAINDICATIONS; WARNINGS; and CLINICAL PHARMACOLOGY, Pharmacokinetics). Because aging is associated with reduced renal function, Metaglip should be used with caution as age increases. Care should be taken in dose selection and should be based on careful and regular monitoring of renal function. Generally, elderly patients should not be titrated to the maximum dose of Metaglip (see also WARNINGS and DOSAGE AND ADMINISTRATION).

Drug Interactions

Certain drugs tend to produce hyperglycemia and may lead to loss of blood glucose 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 Metaglip, the patient should be closely observed for loss of blood glucose control. When such drugs are withdrawn from a patient receiving Metaglip, the patient should be observed closely for hypoglycemia. Metformin is negligibly bound to plasma proteins and is, therefore, less likely to interact with highly protein-bound drugs such as salicylates, sulfonamides, chloramphenicol, and probenecid as compared to sulfonylureas, which are extensively bound to serum proteins.

Glipizide

The hypoglycemic action of sulfonylureas may be potentiated by certain drugs including nonsteroidal anti-inflammatory agents, some azoles, 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 Metaglip, the patient should be observed closely for hypoglycemia. When such drugs are withdrawn from a patient receiving Metaglip, the patient should be observed closely for loss of blood glucose control. In vitro binding studies with human serum proteins indicate that glipizide binds differently than tolbutamide and does not interact with salicylate or dicumarol. However, caution must be exercised in extrapolating these findings to the clinical situation and in the use of Metaglip with these drugs.

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. The effect of concomitant administration of fluconazole and glipizide has been demonstrated in a placebo-controlled crossover study in normal volunteers. All subjects received glipizide alone and following treatment with 100 mg of fluconazole as a single oral daily dose for 7 days, the mean percent increase in the glipizide AUC after fluconazole administration was 56.9% (range: 35-81%).

Metformin HCl

Furosemide

A single-dose, metformin-furosemide drug interaction study in healthy subjects demonstrated that pharmacokinetic parameters of both compounds were affected by coadministration. Furosemide increased the metformin plasma and blood C_max by 22% and blood AUC by 15%, without any significant change in metformin renal clearance. When administered with metformin, the C_max and AUC of furosemide were 31% and 12% smaller, respectively, than when administered alone, and the terminal half-life was decreased by 32%, without any significant change in furosemide renal clearance. No information is available about the interaction of metformin and furosemide when coadministered chronically.

Nifedipine

A single-dose, metformin-nifedipine drug interaction study in normal healthy volunteers demonstrated that coadministration of nifedipine increased plasma metformin C_max and AUC by 20% and 9%, respectively, and increased the amount excreted in the urine. T_max and half-life were unaffected. Nifedipine appears to enhance the absorption of metformin. Metformin had minimal effects on nifedipine.

Cationic Drugs

Cationic drugs (e.g., amiloride, digoxin, morphine, procainamide, quinidine, quinine, ranitidine, triamterene, trimethoprim, or vancomycin) that are eliminated by renal tubular secretion theoretically have the potential for interaction with metformin by competing for common renal tubular transport systems. Such interaction between metformin and oral cimetidine has been observed in normal healthy volunteers in both single- and multiple-dose, metformin-cimetidine drug interaction studies, with a 60% increase in peak metformin plasma and whole blood concentrations and a 40% increase in plasma and whole blood metformin AUC. There was no change in elimination halflife in the single-dose study. Metformin had no effect on cimetidine pharmacokinetics. Although such interactions remain theoretical (except for cimetidine), careful patient monitoring and dose adjustment of Metaglip (glipizide; metformin HCl) tablets and/or the interfering drug is recommended in patients who are taking cationic medications that are excreted via the proximal renal tubular secretory system.

Other

In healthy volunteers, the pharmacokinetics of metformin and propranolol and metformin and ibuprofen were not affected when coadministered in single-dose interaction studies.

Adverse Reactions

In a double-blind 24 week clinical trial involving Metaglip (glipizide; metformin HCl) tablets as initial therapy, a total of 172 patients received Metaglip 2.5 mg/250 mg, 173 received Metaglip 2.5 mg/500 mg, 170 received glipizide, and 177 received metformin. The most common clinical adverse events in these treatment groups are listed in TABLE 4.

In a double-blind 18 week clinical trial involving Metaglip as second-line therapy, a total of 87 patients received Metaglip, 84 received glipizide, and 75 received metformin. The most common clinical adverse events in this clinical trial are listed in TABLE 5.

Hypoglycemia

In a controlled initial therapy trial of Metaglip 2.5 mg/250 mg and 2.5 mg/500 mg the numbers of patients with hypoglycemia documented by symptoms (such as dizziness, shakiness, sweating, and hunger) and a fingerstick blood glucose measurement ≤50 mg/dl were 5 (2.9%) for glipizide, 0 (0%) for metformin, 13 (7.6%) for Metaglip 2.5 mg/250 mg, and 16 (9.3%) for Metaglip 2.5 mg/500 mg. Among patients taking either Metaglip 2.5 mg/250 mg or Metaglip 2.5 mg/500 mg, 9 (2.6%) patients discontinued Metaglip due to hypoglycemic symptoms and 1 required medical intervention due to hypoglycemia. In a controlled second-line therapy trial of Metaglip 5 mg/500 mg, the numbers of patients with hypoglycemia documented by symptoms and a fingerstick blood glucose measurement ≤50 mg/dl were 0 (0%) for glipizide, 1 (1.3%) for metformin, and 11 (12.6%) for Metaglip. One (1.1%) patient discontinued Metaglip therapy due to hypoglycemic symptoms and none required medical intervention due to hypoglycemia. (See PRECAUTIONS.)

Gastrointestinal Reactions

Among the most common clinical adverse events in the initial therapy trial were diarrhea and nausea/vomiting; the incidences of these events were lower with both Metaglip dosage strengths than with metformin therapy. There were 4 (1.2%) patients in the initial therapy trial who discontinued Metaglip therapy due to GI adverse events. Gastrointestinal symptoms of diarrhea, nausea/vomiting, and abdominal pain were comparable among Metaglip, glipizide and metformin in the second-line therapy trial. There were 4 (4.6%) patients in the second-line therapy trial who discontinued Metaglip therapy due to GI adverse events.

Overdosage

Overdosage of sulfonylureas, including glipizide, can produce hypoglycemia. Mild hypoglycemic symptoms, without loss of consciousness or neurological findings, should be treated aggressively with oral glucose and adjustments in drug dosage and/or meal patterns. Close monitoring should continue until the physician is assured that the patient is out of danger. Severe hypoglycemic reactions with coma, seizure, or other neurological impairment occur infrequently, but constitute medical emergencies requiring immediate hospitalization. If hypoglycemic coma is diagnosed or suspected, the patient should be given a rapid IV injection of concentrated (50%) glucose solution. This should be followed by a continuous infusion of a more dilute (10%) glucose solution at a rate that will maintain the blood glucose at a level above 100 mg/dl. Patients should be closely monitored for a minimum of 24-48 hours, since hypoglycemia may recur after apparent clinical recovery. Clearance of glipizide from plasma would be prolonged in persons with liver disease. Because of the extensive protein binding of glipizide, dialysis is unlikely to be of benefit.

Metformin HCl

Among cases of overdosage of metformin HCl, including ingestion of amounts greater than 100 g, hypoglycemia was reported in approximately 10%, but no causal association with metformin HCl has been established, although lactic acidosis has occurred in such circumstances (see WARNINGS). Metformin is dialyzable with a clearance of up to 170 ml/min under good hemodynamic conditions. Therefore, hemodialysis may be useful for removal of accumulated drug from patients in whom metformin overdosage is suspected.

Dosage And Administration

Dosage of Metaglip must be individualized on the basis of both effectiveness and tolerance while not exceeding the maximum recommended daily dose of 20 mg glipizide/2000 mg metformin. Metaglip should be given with meals and should be initiated at a low dose, with gradual dose escalation as described below, in order to avoid hypoglycemia (largely due to glipizide), to reduce GI side effects (largely due to metformin), and to permit determination of the minimum effective dose for adequate control of blood glucose for the individual patient.

With initial treatment and during dose titration, appropriate blood glucose monitoring should be used to determine the therapeutic response to Metaglip and to identify the minimum effective dose for the patient. Thereafter, HbA_1c should be measured at intervals of approximately 3 months to assess the effectiveness of therapy. The therapeutic goal in all patients with Type 2 diabetes is to decrease FPG, PPG, and HbA_1c to normal or as near normal as possible. Ideally, the response to therapy should be evaluated using HbA_1c (glycosylated hemoglobin), which is a better indicator of long-term glycemic control than FPG alone.

No studies have been performed specifically examining the safety and efficacy of switching to Metaglip therapy in patients taking concomitant glipizide (or other sulfonylurea) plus metformin. Changes in glycemic control may occur in such patients, with either hyperglycemia or hypoglycemia possible. Any change in therapy of Type 2 diabetes should be undertaken with care and appropriate monitoring.

Metaglip as Initial Therapy

For patients with Type 2 diabetes whose hyperglycemia cannot be satisfactorily managed with diet and exercise alone, the recommended starting dose of Metaglip is 2.5 mg/250 mg once a day with a meal. For patients whose FPG is 280-320 mg/dl a starting dose of Metaglip 2.5 mg/500 mg twice daily should be considered. The efficacy of Metaglip (glipizide; metformin HCl) tablets in patients whose FPG exceeds 320 mg/dl has not been established. Dosage increases to achieve adequate glycemic control should be made in increments of 1 tablet/day every 2 weeks up to maximum of 10 mg/1000 mg or 10 mg/2000 mg Metaglip per day given in divided doses. In clinical trials of Metaglip as initial therapy, there was no experience with total daily doses greater than 10 mg/2000 mg per/day.

Metaglip as Second-Line Therapy

For patients not adequately controlled on either glipizide (or another sulfonylurea) or metformin alone, the recommended starting dose of Metaglip is 2.5 mg/500 mg or 5 mg/500 mg twice daily with the morning and evening meals. In order to avoid hypoglycemia, the starting dose of Metaglip should not exceed the daily doses of glipizide or metformin already being taken. The daily dose should be titrated in increments of no more than 5 mg/500 mg up to the minimum effective dose to achieve adequate control of blood glucose or to a maximum dose of 20 mg/2000 mg/day.

Patients previously treated with combination therapy of glipizide (or another sulfonylurea) plus metformin may be switched to Metaglip 2.5 mg/500 mg or 5 mg/500 mg; the starting dose should not exceed the daily dose of glipizide (or equivalent dose of another sulfonylurea) and metformin already being taken. The decision to switch to the nearest equivalent dose or to titrate should be based on clinical judgment. Patients should be monitored closely for signs and symptoms of hypoglycemia following such a switch and the dose of Metaglip should be titrated as described above to achieve adequate control of blood glucose.

Specific Patient Populations

Metaglip is not recommended for use during pregnancy or for use in pediatric patients. The initial and maintenance dosing of Metaglip should be conservative in patients with advanced age, due to the potential for decreased renal function in this population. Any dosage adjustment requires a careful assessment of renal function. Generally, elderly, debilitated, and malnourished patients should not be titrated to the maximum dose of Metaglip to avoid the risk of hypoglycemia. Monitoring of renal function is necessary to aid in prevention of metformin-associated lactic acidosis, particularly in the elderly. (See WARNINGS.)

How Supplied

Storage: Store at 20-25°C (68-77°F); excursions permitted to 15-30°C (59-86°F).