Glyburide and Metformin Hydrochloride Tablets
DEFINITION
Glyburide and Metformin Hydrochloride Tablets contain NLT 90.0% and NMT 110.0% of the labeled amounts of glyburide (C23H28ClN3O5S) and metformin hydrochloride (C4H11N5·HCl).
IDENTIFICATION
• A. Glyburide:
The retention time of the glyburide peak of the Sample solution corresponds to that of the major peak 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.
ASSAY
• Glyburide
Solution A:
28.8 g/L of monobasic ammonium phosphate
Mobile phase:
Acetonitrile and Solution A (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: 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 a 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
Mode:
LC
Detector:
UV 230 nm
Column:
4.6-mm × 15-cm; 5-µm packing L7
Column temperature:
40
Flow rate:
1.2 mL/min
Injection size:
100 µL
System suitability
Sample:
System suitability solution 2
[Note—The relative retention time for the peak due to glyburide related compound A is about 0.30 with respect to glyburide. ]
Suitability requirements
Capacity factor, k':
NLT 7 for the peak due to glyburide
Column efficiency:
NLT 3000 theoretical plates for the peak due to glyburide
Relative standard deviation:
NMT 1.5% for the peak due to glyburide
Relative standard deviation:
NMT 10% for the peak due to glyburide related compound A
Analysis
Samples:
Standard solution and Sample solution
Record the chromatograms for about 1.25 times the retention time of the glyburide peak. Calculate the percentage of C23H28ClN3O5S in the Tablets taken:
Result = (rU/rS) × (CS/CU) × 100
| rU | = | = peak response from the Sample solution |
| rS | = | = peak response from the Standard solution |
| CS | = | = concentration of USP Glyburide RS in the Standard solution (mg/mL) |
| CU | = | = nominal concentration of glyburide in the Sample solution (mg/mL) |
Acceptance criteria:
90.0%–110.0% of glyburide label claim
• Metformin Hydrochloride
Solution A:
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 Solution A (10:90)
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
Mode:
LC
Detector:
UV 218 nm
Column:
3.9-mm × 30-cm; 10-µm packing L1
Column temperature:
30
Flow rate:
1 mL/min
Injection size:
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.) ]
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 and NMT 10% for each of the peaks due to metformin related compound B and metformin related compound C.
Analysis
Samples:
Standard solution and Sample solution
Calculate the percentage of C4H11N5·HCl in the Tablets taken:
Result = (rU/rS) × (CS/CU) × 100
| rU | = | = peak response from the Sample solution |
| rS | = | = peak response from the Standard solution |
| CS | = | = concentration of USP Metformin Hydrochloride RS in the Standard solution (mg/mL) |
| CU | = | = nominal concentration of metformin hydrochloride in the Sample solution (mg/mL) |
Acceptance criteria:
90.0%–110.0% of metformin label claim
PERFORMANCE TESTS
• Dissolution 
711
711
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:
Transfer 10 mg of USP Glyburide RS to a 100-mL volumetric flask. Dissolve in 20 mL of acetonitrile, and 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, in mg, of glyburide.
Sample solution:
Sample per Dissolution 711. Pass a portion of the solution under test through a 0.45-µm polypropylene filter or a 1-µm glass fiber filter. Dilute with Medium, if necessary.
711. Pass a portion of the solution under test through a 0.45-µm polypropylene filter or a 1-µm glass fiber filter. Dilute with Medium, if necessary.
Solution A:
28.7 mg/mL of monobasic ammonium phosphate in water
Mobile phase:
Solution A and acetonitrile (1:1). Adjust with 1 N sodium hydroxide to a pH of 5.3.
Chromatographic system
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 size:
200 µL
System suitability
Sample:
Standard solution
Suitability requirements
Column efficiency:
NLT 5000
Tailing factor:
0.8–2.0
Relative standard deviation:
NMT 2%
Analysis
Samples:
Standard solution and Sample solution
Determine the percentage of C23H28ClN3O5S dissolved:
Result = (rU/rS) × (CS/CU) × 100
| rU | = | = peak response from the Sample solution |
| rS | = | = peak response from the Standard solution |
| CS | = | = concentration of the Standard solution (mg/mL) |
| CU | = | = nominal concentration of glyburide in the Sample solution (mg/mL) |
Tolerances:
NLT 85% (Q) of the labeled amount of glyburide is dissolved.
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. Dilute further, if necessary, with Medium to obtain a solution having a metformin hydrochloride concentration, in mg/mL, of L/1000 where L is the label claim, in mg, of metformin hydrochloride.
Sample solution:
Sample per Dissolution 711. Pass a portion of the solution under test through a 0.45-µm polypropylene filter or a 1-µm glass fiber filter. Dilute with Medium, if necessary.
711. Pass a portion of the solution under test through a 0.45-µm polypropylene filter or a 1-µm glass fiber filter. Dilute with Medium, if necessary.
Spectrometric conditions
Mode:
UV-Vis
Analytical wavelength:
232 nm
Analysis
Samples:
Standard solution and Sample solution
Calculate the percentage of C4H11N5·HCl dissolved:
Result = (AU/AS) × (CS/CU) × 100
| AU | = | = absorbance of the Sample solution |
| AS | = | = absorbance of the Standard solution |
| CS | = | = concentration of USP Metformin Hydrochloride RS in the Standard solution (mg/mL) |
| CU | = | = nominal concentration of metformin hydrochloride in the Sample solution (mg/mL) |
Tolerances:
NLT 85% (Q) of the labeled amount of metformin hydrochloride is dissolved.
• Uniformity of Dosage Units 905:
Meet the requirements for Weight Variation for metformin hydrochloride and for Content Uniformity for glyburide
905:
Meet the requirements for Weight Variation for metformin hydrochloride and for Content Uniformity for glyburide
IMPURITIES
Organic Impurities
• Procedure 1: Glyburide
Solution A, 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 Tablets:
Result = (rU/rS) × (CS/CU) × F × 100
| rU | = | = peak response from the Sample solution |
| rS | = | = peak response from the Standard solution |
| CS | = | = concentration of USP Glyburide RS in the Standard solution (mg/mL) |
| CU | = | = nominal concentration of glyburide in the Sample solution (mg/mL) |
| F | = | = relative response factor, use 0.8 for glyburide related compound A, and use 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
• Procedure 2: Metformin Hydrochloride
Solution A, 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 impurity in the portion of Tablets taken:
Result = (rU/rT) × 100
| rU | = | = peak response for each impurity from the Sample solution |
| rT | = | = sum of the responses of all peaks from the Sample solution |
Acceptance criteria
[Note—Disregard any peak less than 0.05%, and disregard any peak observed in the blank. ]
Individual impurities:
NMT 0.1%
Total impurities:
NMT 0.5 %
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in tight, light-resistant containers, and store at controlled room temperature.
• USP Reference Standards 11
11
USP Glyburide RS 
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USP Glyburide Related Compound A RS
(4-[2-(5-Chloro-2-methoxybenzamido)ethyl]benzenesulfonamide.
(4-[2-(5-Chloro-2-methoxybenzamido)ethyl]benzenesulfonamide.
USP Metformin Hydrochloride RS
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USP Metformin Related Compound B RS
1-Methylbiguanide.
C3H9N5 115.14
1-Methylbiguanide.
C3H9N5 115.14
USP Metformin Related Compound C RS
Dimethylmelamine, or N,N-dimethyl-[1,3,5]triazine-2,4,6-triamine.
C5H10N6 154.17
Dimethylmelamine, or N,N-dimethyl-[1,3,5]triazine-2,4,6-triamine.
C5H10N6 154.17
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Elena Gonikberg, Ph.D.
Principal Scientific Liaison 1-301-816-8251 |
(SM32010) Monographs - Small Molecules 3 |
| 711 |
Margareth R.C. Marques, Ph.D.
Senior Scientific Liaison 1-301-816-8106 |
(GCDF2010) General Chapters - Dosage Forms |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 3350
Pharmacopeial Forum: Volume No. 35(6) Page 1456