Glyburide and Metformin Hydrochloride Tablets

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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1 DEFINITION

Glyburide and Metformin Hydrochloride Tablets contain NLT 90.0% and NMT 110.0% of the labeled amounts of glyburide (C₂₃H₂₈CIN₃O₅S) and metformin hydrochloride (C₄H₁₁N₅·HCI).

2 IDENTIFICATION

A. GLYBURIDE: The retention time of the glyburide peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay for Glyburide.

B. Metformin HYDROCHLORIDE: The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay for Metformin Hydrochloride.

3 ASSAY

3.1 GLYBURIDE

Buffer: 28.8 g/L of monobasic ammonium phosphate

Mobile phase: Acetonitrile and Buffer (40:60). Adjust with 1 N sodium hydroxide to a pH of 5.3.

Diluent: Acetonitrile and water (50:50)

Standard stock solution: 0.25 mg/mL of USP Glyburide RS prepared as follows. Transfer a weighed amount of USP Glyburide RS to a suitable volumetric flask. Dissolve first in the acetonitrile, using 50% of the final volume, and then dilute with water to volume.

Standard solution: 0.025 mg/mL of USP Glyburide RS in Diluent, from the Standard stock solution

System suitability solution 1: Prepare a solution containing 0.025 mg/mL of USP Glyburide Related Compound A RS in Diluent. Transfer 50 µL of this solution to a 50-mL volumetric flask, and dilute with Standard solution to volume.

System suitability solution 2: 5.0 mg/mL of USP Metformin Hydrochloride RS in System suitability solution 1

Sample solution: Dissolve NLT 5 Tablets in Diluent by stirring with a magnetic stirring bar for at least 1 h. Dilute to obtain a solution containing 0.025 mg/mL of glyburide, based on the label claim. Centrifuge a portion of this solution at 3000 rpm for 10 min and use the clear supernatant. [NOTE-Retain a portion of this solution for the Assay for Metformin Hydrochloride.]

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 230 nm

Column: 4.6-mm x 15-cm; 5-µm packing L7

Column temperature: 40°

Flow rate: 1.2 mL/min

Injection volume: 100 µL

Run time: 1.25 times the retention time of glyburide

System suitability

Sample: System suitability solution 2

[NOTE-The relative retention time for glyburide related compound A is about 0.30 with respect to glyburide.]

Suitability requirements

Relative standard deviation: NMT 1.5% for the glyburide peak; NMT 10% for the glyburide related compound A peak

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of glyburide (C₂₃H₂₈CIN₃O₅S) in the portion of Tablets taken:

Result = (r_U/r_S) x (C_S/C_U) x 100

r_U = peak response of glyburide from the Sample solution

r_S = peak response of glyburide from the Standard solution

C_S = concentration of USP Glyburide RS in the Standard solution (mg/mL)

C_U = nominal concentration of glyburide in the Sample solution (mg/mL)

Acceptance criteria: 90.0%-110.0% of the labeled amount of glyburide

3.2 METFORMIN HYDROCHLORIDE

Buffer: Transfer 1.0 g each of sodium heptanesulfonate and sodium chloride to a 2000-mL volumetric flask. Add 1800 mL of water, and adjust with 0.06 M phosphoric acid to a pH of 3.85. Dilute with water to volume.

Mobile phase: Acetonitrile and Buffer (10:90)

[NOTE-To improve the separation, the composition of acetonitrile and Buffer may be changed to 5:95, if necessary.]

Diluent: Acetonitrile and water (1:40)

Standard solution: 0.25 mg/mL of USP Metformin Hydrochloride RS in Diluent. [NOTE-Sonicate to achieve complete dissolution, if necessary.]

System suitability stock solution: 25 µg/mL each of USP Metformin Related Compound B RS and USP Metformin Related Compound C RS in Diluent

System suitability solution: Transfer 0.5 mL of the System suitability stock solution to a 50-mL volumetric flask, and dilute with Standard solution to volume.

Sample solution: Dilute with water a portion of the retained Sample solution from the Assay for Glyburide to obtain 0.25 mg/mL of metformin hydrochloride based on the label claim.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 218 nm

Column: 3.9-mm x 30-cm; 10-µm packing L1

Column temperature: 30°

Flow rate: 1 mL/min

Injection volume: 5 µL

System suitability

Sample: System suitability solution

[NOTE-The relative retention times for metformin related compound B, metformin, and metformin related compound C are about 0.86, 1.0, and 2.1-2.3, respectively. Metformin related compound C can have a variable retention time. The composition of acetonitrile and Buffer in Mobile phase may be changed to 5:95, if it elutes at a relative retention time of less than 2.1.]

Suitability requirements

Resolution: NLT 1.5 between metformin related compound B and metformin

Tailing factor: 0.8-2.0 for the metformin peak

Relative standard deviation: NMT 1.5% for the metformin peak; NMT 10% each for the metformin related compound B and metformin related compound C peaks

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of metformin hydrochloride (C₄H₁₁N₅·HCI) in the portion of Tablets taken:

Result = (r_U/r_S) x (C_S/C_U) x 100

r_U = peak response of metformin from the Sample solution

r_S = peak response of metformin from the Standard solution

C_S = concentration of USP Metformin Hydrochloride RS in the Standard solution (mg/mL)

C_U = nominal concentration of metformin hydrochloride in the Sample solution (mg/mL)

Acceptance criteria: 90.0%-110.0% of the labeled amount of metformin hydrochloride

4 PERFORMANCE TESTS

4.1 DISSOLUTION (711)

4.1.1 Test 1

4.1.1.1 Glyburide

Medium: 0.05 M boric acid and 0.05 M potassium chloride solution. Prepare by dissolving 3.09 g of boric acid and 3.73 g of potassium chloride in 250 mL of water, adjust with 1 N sodium hydroxide to a pH of 9.5, and dilute with water to 1 L; 500 mL.

Apparatus 2: 75 rpm

Time: 30 min

Standard solution: 0.1 mg/mL of USP Glyburide RS prepared as follows. Transfer a weighed amount of USP Glyburide RS to a suitable volumetric flask, dissolve first in acetonitrile, using 20% of the final volume, then dilute with Medium to volume. Dilute further with Medium to obtain a solution having a glyburide concentration, in mg/mL, of (L/500), where L is the label claim of glyburide in mg/Tablet.

Sample solution: Sample per Dissolution (711). Pass a portion of the solution under test through a polypropylene filter of 0.45-µm pore size or a glass fiber filter of 1-µm pore size.

Buffer: 28.8 g/L of monobasic ammonium phosphate in water

Mobile phase: Acetonitrile and Buffer (1:1). Adjust with 1 N sodium hydroxide to a pH of 5.3.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 230 nm

Column: 4.6-mm × 15-cm; 5-µm packing L7

Column temperature: 30°

Flow rate: 1.5 mL/min

Injection volume: 200 µL

System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: 0.8-2.0

Relative standard deviation: NMT 2%

Analysis

Samples: Standard solution and Sample solution

Determine the percentage of the labeled amount of glyburide (C₂₃H₂₈CIN₃O₅S) dissolved:

Result = (r_U/r_S) x (C_S/L) x V x 100

r_U = peak response of glyburide from the Sample solution

r_S = peak response of glyburide from the Standard solution

C_S = concentration of USP Glyburide RS in the Standard solution (mg/mL)

L = label claim of glyburide (mg/Tablet)

V = volume of Medium, 500 mL

Tolerances: NLT 85% (Q) of the labeled amount of glyburide is dissolved.

4.1.1.2 Metformin hydrochloride

Medium: 0.05 M phosphate buffer, pH 6.8. Prepare by dissolving 6.8 g of monobasic potassium phosphate in 1000 mL of water, and adjust with 0.2 N sodium hydroxide to a pH of 6.8 ± 0.1; 1000 mL.

Apparatus 2: 50 rpm

Time: 30 min

Standard solution: Dissolve a quantity of USP Metformin Hydrochloride RS in Medium, to obtain a solution having a metformin hydrochloride concentration, in mg/mL, of (L/1000), where L is the label claim of metformin hydrochloride in mg/Tablet. Dilute further, if necessary, with Medium.

Sample solution: Sample per Dissolution (711), Pass a portion of the solution under test through a polypropylene filter of 0.45-µm pore size or a glass fiber filter of 1-um pore size. Dilute with Medium, if necessary, to a concentration similar to that of the Standard solution.

Instrumental conditions

(See Ultraviolet-Visible Spectroscopy (857).)

Mode: UV-Vis

Analytical wavelength: 232 nm

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of metformin hydrochloride (C₄H₁₁N₅·HCI) dissolved:

Result = (A_U/A_S) x (C_S/L) x V x D x 100

A_U = absorbance of the Sample solution

A_S = absorbance of the Standard solution

C_S = concentration of USP Metformin Hydrochloride RS in the Standard solution (mg/mL)

L = label claim (mg/Tablet)

V = volume of Medium, 1000 mL

D = dilution factor for the Sample solution

Tolerances: NLT 85% (Q) of the labeled amount of metformin hydrochloride is dissolved.

4.1.2 Test 2

4.1.2.1 Glyburide

Medium: 0.05 M boric acid and 0.05 M potassium chloride solution. Prepare by dissolving 3.09 g of boric acid and 3.73 g of potassium chloride in 250 mL of water, adjust with 1 N sodium hydroxide to a pH of 9.5, and dilute with water to 1 L; 500 mL.

Apparatus 2: 75 rpm

Time: 30 min

Solution A: Dissolve 0.288 g of sodium lauryl sulfate in 700 mL water.

Mobile phase: Acetonitrile, Solution A, and triethylamine (300:700:2). Adjust with phosphoric acid to a pH of 7.2.

Standard stock solution: 0.1 mg/mL of USP Glyburide RS prepared in acetonitrile

Standard solution: Dilute Standard stock solution with Medium to obtain a solution having a glyburide concentration, in mg/mL, of (L/500), where L is the label claim of glyburide in mg/Tablet.

Sample solution: Sample per Dissolution (711). Pass a portion of the solution under test through a membrane filter of 0.45-µm pore size.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 220 nm

Column: 4.6-mm × 15-cm; 5-µm packing L7

Column temperature: 40°

Flow rate: 2 mL/min

Injection volume

For Tablets labeled to contain 5 mg/500 mg and 2.5 mg/500 mg: 20 µL

For Tablets labeled to contain 1.25 mg/250 mg: 50 µL

Run time: 8 min

System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 2.0%

Analysis

Samples: Standard solution and Sample solution

Determine the percentage of the labeled amount of glyburide (C₂₃H₂₈CIN₃O₅S) dissolved:

Result = (r_U/r_S) x (C_S/L) x V x 100

r_U = peak response of glyburide from the Sample solution

r_S = peak response of glyburide from the Standard solution

C_S = concentration of USP Glyburide RS in the Standard solution (mg/mL)

L = label claim of glyburide (mg/Tablet)

V = volume of Medium, 500 mL

Tolerances: NLT 80% (Q) of the labeled amount of glyburide is dissolved.

4.1.2.2 Metformin hydrochloride

Medium: 0.05 M phosphate buffer, pH 6.8. Prepare by dissolving 6.8 g of monobasic potassium phosphate in 1000 mL of water, and adjust with 0.2 N sodium hydroxide to a pH of 6.8 ± 0.1; 1000 mL.

Apparatus 2: 50 rpm

Time: 30 min

Solution A: Dissolve 0.288 g of sodium lauryl sulfate in 700 mL of water.

Mobile phase: Acetonitrile, Solution A, and triethylamine (300:700:2). Adjust with phosphoric acid to a pH of 7.2.

Standard solution

For Tablets labeled to contain 5 mg/500 mg and 2.5 mg/500 mg: 0.5 mg/mL of USP Metformin Hydrochloride RS in Medium. Sonicate before final dilution.

For Tablets labeled to contain 1.25 mg/250 mg: 0.25 mg/mL of USP Metformin Hydrochloride RS in Medium. Sonicate before final dilution.

Sample solution: Sample per Dissolution (711), Pass a portion of the solution under test through a membrane filter of 0.45-um pore size.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 254 nm

Column: 4.6-mm × 15-cm; 5-µm packing L7

Column temperature: 40°

Flow rate: 2 mL/min

Injection volume

For Tablets labeled to contain 5 mg/500 mg and 2.5 mg/500 mg: 20 µL

For Tablets labeled to contain 1.25 mg/250 mg: 50 µL

Run time: 8 min

System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 2.0%

Analysis

Samples: Standard solution and Sample solution

Determine the percentage of the labeled amount of metformin hydrochloride (C₄H₁₁N₅·HCI) dissolved:

Result = (r_U/r_S) x (C_S/L) x V x 100

r_U = peak response of the Sample solution

r_S = peak response of the Standard solution

C_S = concentration of USP Metformin Hydrochloride RS in the Standard solution (mg/mL)

L = label claim (mg/Tablet)

V = volume of Medium, 1000 mL

Tolerances: NLT 85% (Q) of the labeled amount of metformin hydrochloride is dissolved.

4.2 UNIFORMITY OF DOSAGE UNITS (905)

Meet the requirements for Weight Variation for metformin hydrochloride and for Content Uniformity for glyburide

5 IMPURITIES

5.1 GLYBURIDE

Buffer, Mobile phase, Diluent, Sample solution, Chromatographic system, and System suitability: Proceed as directed in the Assay for Glyburide.

Standard solution: Dilute 1.0 mL of the Standard solution from the Assay for Glyburide with Diluent to 100 mL.

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of each glyburide impurity in the portion of Tablets taken:

Result = (r_U/r_S) x (C_S/C_U) x (1/F) x 100

r_U = peak response of each glyburide impurity from the Sample solution

r_S = peak response of glyburide from the Standard solution

C_S = concentration of USP Glyburide RS in the Standard solution (mg/mL)

C_U = nominal concentration of glyburide in the Sample solution (mg/mL)

F = relative response factor, 1.2 for glyburide related compound A, 1.0 for all other impurities

Acceptance criteria

[NOTE-Disregard any peak less than 0.05%, and disregard any peak observed in the blank.]

Glyburide related compound A: NMT 1.0%

Any other individual impurities: NMT 0.2%

Total impurities: NMT 0.50%, excluding glyburide related compound A

5.2 METFORMIN HYDROCHLORIDE

Buffer, Mobile phase, Sample solution, Chromatographic system, and System suitability: Proceed as directed in the Assay for Metformin Hydrochloride.

Analysis

Sample: Sample solution

Calculate the percentage of each metformin impurity in the portion of Tablets taken:

Result = (r_U/r_T) x 100

r_U = peak response of each metformin impurity from the Sample solution

r_T = sum of all the peak responses from the Sample solution

Acceptance criteria

[Note—Disregard any peak less than 0.05%, and disregard any peak observed in the blank.]

Individual metformin impurities: NMT 0.1%

Total impurities: NMT 0.5%

6 ADDITIONAL REQUIREMENTS

6.1 PACKAGING AND STORAGE

Preserve in tight, light-resistant containers, and store at controlled room temperature.

6.2 LABELING

When more than one dissolution test is given, the labeling states the Dissolution test used only if Test 1 is not used.

Change to read:

6.3 USP REFERENCE STANDARDS (11)

USP Glyburide RS

USP Glyburide Related Compound A RS

4-[2-(5-Chloro-2-methoxybenzamido)ethyl]benzenesulfonamide.

C₁₆H₁₇CIN₂O₄S 368.83(ERR 1-Apr-2021)

USP Metformin Hydrochloride RS

USP Metformin Related Compound B RS

1-Methylbiguanide hydrochloride.

C₃H₉N₅·HCI 151.60

USP Metformin Related Compound C RS

Dimethylmelamine, or N,N-dimethyl-[1,3,5]triazine-2,4,6-triamine.

C₅H₁₀N₆ 154.17