Glipizide and Metformin Hydrochloride (glipizide 5 mg metformin hydrochloride 500 mg) Dailymed

Glipizide And Metformin Hydrochloride Tablets, Usp Rx Only

Description

Glipizide and metformin hydrochloride tablets, USP contain 2 oral antihyperglycemic drugs used in the management of type 2 diabetes, glipizide, USP and metformin hydrochloride, USP.

Glipizide, USP is an oral antihyperglycemic drug of the sulfonylurea class. The chemical name for glipizide, USP is 1-cyclohexyl-3-[[p-[2-(5-methylpyrazinecarboxamido)ethyl]phenyl]sulfonyl]urea. Glipizide, USP is a whitish, odorless powder with 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. The structural formula is represented below.

C₂₁H₂₇N₅O₄S M.W. 445.55

Metformin hydrochloride, USP is an oral antihyperglycemic drug used in the management of type 2 diabetes. Metformin hydrochloride, USP (N,N-dimethylimidodicarbonimidic diamide monohydrochloride) is not chemically or pharmacologically related to sulfonylureas, thiazolidinediones, or α-glucosidase inhibitors. It is a white to off-white crystalline compound. Metformin hydrochloride, USP 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, USP is 6.68. The structural formula is as shown:

C₄H₁₂ClN₅ M.W. 165.63

Glipizide and metformin hydrochloride tablets, USP for oral administration contain 2.5 mg glipizide, USP with 250 mg metformin hydrochloride, USP, 2.5 mg glipizide, USP with 500 mg metformin hydrochloride, USP, and 5 mg glipizide, USP with 500 mg metformin hydrochloride, USP. In addition, each tablet contains the following inactive ingredients: corn starch, croscarmellose sodium, magnesium stearate, microcrystalline cellulose, polyethylene glycol, polyvinyl alcohol-part. hydrolyzed, povidone, talc, and titanium dioxide. Additionally, 2.5 mg/250 mg and 5 mg/500 mg tablets contain iron oxide black, iron oxide red, and iron oxide yellow. The tablets are film-coated, which provides color differentiation.

Clinical Pharmacology

Mechanism of Action

Glipizide and metformin hydrochloride tablets combine glipizide and metformin hydrochloride, 2 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 hydrochloride is an antihyperglycemic agent that improves glucose tolerance in patients with type 2 diabetes, lowering both basal and postprandial plasma glucose. Metformin hydrochloride decreases hepatic glucose production, decreases intestinal absorption of glucose, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization.

Pharmacokinetics

In a single-dose study in healthy subjects, the glipizide and metformin components of glipizide and metformin hydrochloride tablets, 5 mg/500 mg were bioequivalent to coadministered glipizide tablets and metformin hydrochloride tablets. Following administration of a single glipizide and metformin hydrochloride 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.

Gastrointestinal absorption of glipizide is uniform, rapid, and essentially complete. Peak plasma concentrations occur 1 to 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.

The absolute bioavailability of a 500 mg metformin hydrochloride tablet given under fasting conditions is approximately 50% to 60%. Studies using single oral doses of metformin tablets of 500 mg and 1500 mg, and 850 mg to 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.

Protein binding was studied in serum from volunteers who received either oral or intravenous glipizide and found to be 98% to 99% 1 hour after either route of administration. The apparent volume of distribution of glipizide after intravenous administration was 11 liters, 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.

The apparent volume of distribution (V/F) of metformin following single oral doses of 850 mg averaged 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 to 48 hours and are generally < 1 mcg/mL. During controlled clinical trials, maximum metformin plasma levels did not exceed 5 mcg/mL, even at maximum doses.

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 to 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.

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.

Specific Populations

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.

The metabolism and excretion of glipizide may be slowed in patients with impaired renal function (see CONTRAINDICATIONS, WARNINGS, PRECAUTIONS, and DOSAGE AND ADMINISTRATION).

In patients with decreased renal function, the plasma and blood half-life of metformin is prolonged and the renal clearance is decreased (see Table 1; also, see WARNINGS).

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.

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, when 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).

Table 1: Select Mean (± SD) Metformin Pharmacokinetic Parameters Following Single or Multiple Oral Doses of Metformin

Subject Groups: Metformin Dose All doses given fasting except the first 18 doses of the multiple-dose studies (Number of Subjects)	Cmax Peak plasma concentration (mcg/mL)	Tmax Time to peak plasma concentration (hrs)	Renal Clearance (mL/min)
Healthy, Nondiabetic Adults:
500 mg SDSD = single dose (24)	1.03 (± 0.33)	2.75 (± 0.81)	600 (± 132)
850 mg SD (74)Combined results (average means) of 5 studies: mean age 32 years (range 23 to 59 years)	1.60 (± 0.38)	2.64 (± 0.82)	552 (± 139)
850 mg t.i.d. for 19 dosesKinetic study done following dose 19, given fasting (9)	2.01 (± 0.42)	1.79 (± 0.94)	642 (± 173)
Adults with Type 2 Diabetes:
850 mg SD (23)	1.48 (± 0.5)	3.32 (± 1.08)	491 (± 138)
850 mg t.i.d. for 19 doses (9)	1.90 (± 0.62)	2.01 (± 1.22)	550 (± 160)
Elderly Elderly subjects, mean age 71 years (range 65 to 81 years) , Healthy Nondiabetic Adults:
850 mg SD (12)	2.45 (± 0.70)	2.71 (± 1.05)	412 (± 98)
Renal-impaired Adults: 850 mg SD
Mild (CLcr CLcr = creatinine clearance normalized to body surface area of 1.73 m2 61 to 90 mL/min) (5)	1.86 (± 0.52)	3.20 (± 0.45)	384 (± 122)
Moderate (CLcr 31 to 60 mL/min) (4)	4.12 (± 1.83)	3.75 (± 0.50)	108 (± 57)
Severe (CLcr 10 to 30 mL/min) (6)	3.93 (± 0.92)	4.01 (± 1.10)	130 (± 90)

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

After administration of a single oral metformin 500 mg tablet with food, geometric mean metformin C_max and AUC differed < 5% between pediatric type 2 diabetic patients (12 to 16 years of age) and gender- and weight-matched healthy adults (20 to 45 years of age), all with normal renal function.

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.

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, glipizide and metformin hydrochloride tablets, 2.5 mg/250 mg, or glipizide and metformin hydrochloride tablets, 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.

Table 2: Active-Controlled Trial of Glipizide and Metformin Hydrochloride Tablets in Patients With Inadequate Glycemic Control on Diet and Exercise Alone: Summary of Trial Data at 24 Weeks

	Glipizide 5 mg Tablets	Metformin 500 mg Tablets	Glipizide and Metformin Hydrochloride Tablets, 2.5 mg/250 mg	Glipizide and Metformin Hydrochloride Tablets, 2.5 mg/500 mg
Mean Final Dose	16.7 mg	1749 mg	7.9 mg/791 mg	7.4 mg/1477 mg
Hemoglobin A 1c (%)	N = 168	N = 171	N = 166	N = 163
Baseline Mean	9.17	9.15	9.06	9.10
Final Mean	7.36	7.67	6.93	6.95
Adjusted Mean Change from Baseline	-1.77	-1.46	-2.15	-2.14
Difference from Glipizide			-0.38p < 0.001	-0.37
Difference from Metformin			-0.70	-0.69
% Patients with Final HbA1c < 7%	43.5%	35.1%	59.6%	57.1%
Fasting Plasma Glucose (mg/dL)	N = 169	N = 176	N = 170	N = 169
Baseline Mean	210.7	207.4	206.8	203.1
Final Mean	162.1	163.8	152.1	148.7
Adjusted Mean Change from Baseline	-46.2	-42.9	-54.2	-56.5
Difference from Glipizide			-8.0	-10.4
Difference from Metformin			-11.3	-13.6

After 24 weeks, treatment with glipizide and metformin hydrochloride tablets, 2.5 mg/250 mg and 2.5 mg/500 mg resulted in significantly greater reduction in HbA_1c compared to glipizide and metformin therapy. Also, glipizide and metformin hydrochloride tablet, 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 glipizide and metformin hydrochloride tablets 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, glipizide and metformin hydrochloride tablets 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 glipizide and metformin hydrochloride tablet therapy and either metformin therapy or glipizide therapy. The adjusted mean changes from baseline in body weight were: glipizide and metformin hydrochloride tablets, 2.5 mg/250 mg, -0.4 kg; glipizide and metformin hydrochloride tablets, 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 glipizide and metformin hydrochloride tablets.

In an 18-week, double-blind, active-controlled U.S. 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 glipizide and metformin hydrochloride tablets, 5 mg/500 mg. The doses of metformin and glipizide and metformin hydrochloride tablets 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.

Table 3: Glipizide and Metformin Hydrochloride Tablets in Patients With Inadequate Glycemic Control on Sulfonylurea Alone: Summary of Trial Data at 18 Weeks

	Glipizide 5 mg Tablets	Metformin 500 mg Tablets	Glipizide and Metformin Hydrochloride Tablets, 5 mg/500 mg
Mean Final Dose	30.0 mg	1927 mg	17.5 mg/1747 mg
Hemoglobin A 1c (%)	N = 79	N = 71	N = 80
Baseline Mean	8.87	8.61	8.66
Final Adjusted Mean	8.45	8.36	7.39
Difference from Glipizide			-1.06p < 0.001
Difference from Metformin			-0.98
% Patients with Final HbA1c < 7%	8.9%	9.9%	36.3%
Fasting Plasma Glucose (mg/dL)	N = 82	N = 75	N = 81
Baseline Mean	203.6	191.3	194.3
Adjusted Mean Change from Baseline	7.0	6.7	-30.4
Difference from Glipizide			-37.4
Difference from Metformin			-37.2

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

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

Indications And Usage

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

Contraindications

Glipizide and metformin hydrochloride tablets are contraindicated in patients with:

• Severe renal impairment (eGFR below 30 mL/min/1.73 m²) (see WARNINGS and PRECAUTIONS).
• Known hypersensitivity to glipizide or metformin hydrochloride.
• Acute or chronic metabolic acidosis, including diabetic ketoacidosis, with or without coma. Diabetic ketoacidosis should be treated with insulin.

Warnings

BOXED WARNING SECTION

WARNING: LACTIC ACIDOSIS

Postmarketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension, and resistant bradyarrhythmias. The onset of metformin-associated lactic acidosis is often subtle, accompanied only by nonspecific symptoms such as malaise, myalgias, respiratory distress, somnolence, and abdominal pain. Metformin-associated lactic acidosis was characterized by elevated blood lactate levels (> 5 mmol/Liter), anion gap acidosis (without evidence of ketonuria or ketonemia), an increased lactate/pyruvate ratio; and metformin plasma levels generally > 5 mcg/mL [see PRECAUTIONS].

Risk factors for metformin-associated lactic acidosis include renal impairment, concomitant use of certain drugs (e.g., carbonic anhydrase inhibitors such as topiramate), age 65 years old or greater, having a radiological study with contrast, surgery and other procedures, hypoxic states (e.g., acute congestive heart failure), excessive alcohol intake, and hepatic impairment.

Steps to reduce the risk of and manage metformin-associated lactic acidosis in these high risk groups are provided [see PRECAUTIONS].

If metformin-associated lactic acidosis is suspected, immediately discontinue glipizide and metformin hydrochloride tablets and institute general supportive measures in a hospital setting. Prompt hemodialysis is recommended [see PRECAUTIONS].

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 to 8 years with diet plus a fixed dose of tolbutamide (1.5 grams per 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 1 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.