Glyburide and Metformin Hydrochloride Tablets
» Glyburide and Metformin Hydrochloride Tablets contain not less than 90.0 percent and not more than 110.0 percent of the labeled amounts of glyburide (C23H28ClN3O5S) and metformin hydrochloride (C4H11N5·HCl).
Packaging and storage— Preserve in tight, light-resistant containers, and store at controlled room temperature.
Identification—
A: glyburide—
Infrared Absorption 197KPrepare the test specimen as follows. Grind 5 Tablets to a fine powder. Add 25 mL of water, and shake for 5 minutes. Add 25 mL of chloroform, and shake for an additional 5 minutes. Centrifuge at 2500 rpm for 5 minutes. Transfer the lower chloroform layer to another container, evaporate the solvent under a stream of nitrogen, and dry the extract at 60 for 3 hours: the IR absorption spectrum of a potassium bromide dispersion prepared from the residue so obtained exhibits maxima only at the same wavelengths as that of a similar preparation of USP Glyburide RS.
B: metformin hydrochloride—
The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay for metformin hydrochloride.
Dissolution 711
glyburide
Medium: 0.05 M boric acid and 0.05 M potassium chloride solution, prepared by dissolving 3.09 g of boric acid and 3.73 g of potassium chloride in approximately 250 mL of water, adjusting with 1 N sodium hydroxide to a pH of 9.5, and diluting with water to 1 L; 500 mL.
Apparatus 2: 75 rpm.
Time: 30 minutes.
Determine the amount of glyburide (C23H28ClN3O5S) dissolved by employing the following method.
Phosphate buffer— Dissolve 28.7 g of monobasic ammonium phosphate in water, and dilute with water to 1 L.
Mobile phase— Prepare a filtered and degassed mixture of Phosphate buffer and acetonitrile (1:1), and adjust with 1 N sodium hydroxide to a pH of 5.3. Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard solution— Transfer about 10 mg of USP Glyburide RS, accurately weighed, 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 per mL, of L/500, where L is the label claim, in mg, of glyburide.
Test solution— Pass a portion of the solution under test through a 0.45-µm polypropylene filter or a 1-µm glass fiber filter.
Chromatographic system (see Chromatography 621) The liquid chromatograph is equipped with a 230-nm detector and a 4.6-mm × 15-cm column that contains 5-µm packing L7. The flow rate is about 1.5 mL per minute. The column temperature is maintained at 30. Chromatograph the Standard solution, and record the peak responses as directed for Procedure: the column efficiency is not less than 5000 theoretical plates; the tailing factor is between 0.8 and 2.0; and the relative standard deviation for replicate injections is not more than 2%.
Procedure— Separately inject equal volumes (about 200 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the responses for the glyburide peaks. Calculate the quantity of glyburide dissolved, expressed as a percentage of the glyburide label claim, by the formula:
Click to View Image
in which rU and rS are the peak responses for the Test solution and the Standard solution, respectively; CS is the concentration, in mg per mL, of the Standard solution; 500 is the volume, in mL, of Medium; 100 is the conversion factor to percentage; and L is the Tablet label claim, in mg, of glyburide.
Tolerances— Not less than 85% (Q) of the labeled amount of glyburide is dissolved in 30 minutes.
metformin hydrochloride
Medium: 0.05 M phosphate buffer, pH 6.8, prepared by dissolving 6.8 g of monobasic potassium phosphate in 1000 mL of water, and adjusting with 0.2 N sodium hydroxide to a pH of 6.8 ± 0.1; 1000 mL.
Apparatus 2: 50 rpm.
Time: 30 minutes.
Determine the amount of metformin hydrochloride (C4H11N5·HCl) dissolved by employing the following method.
Standard solution— Dissolve an accurately weighed quantity of USP Metformin Hydrochloride RS in Medium. Dilute with Medium, if necessary, to obtain a solution having a concentration, in mg per mL, of metformin hydrochloride of about L/1000, where L is the label claim, in mg, of metformin hydrochloride.
Test solution— Pass a portion of the solution under test through a 0.45-µm polypropylene filter or a 1-µm glass fiber filter.
Procedure— Determine the amount of metformin hydrochloride dissolved by employing UV absorption at the wavelength of maximum absorbance at about 232 nm on portions of the Test solution in comparison with the Standard solution. Calculate the percentage of metformin hydrochloride dissolved, expressed as a percentage of the metformin hydrochloride label claim, by the formula:
Click to View Image
in which AU and AS are the absorbances obtained from the Test solution and the Standard solution, respectively; CS is the concentration, in mg per mL, of USP Metformin Hydrochloride RS in the Standard solution; 1000 is the volume, in mL, of Medium; 100 is the conversion factor to percentage; and L is the Tablet label claim, in mg.
Tolerances— Not less than 85% (Q) of the labeled amount of metformin hydrochloride is dissolved in 30 minutes.
Uniformity of dosage units 905: meet the requirements for Weight variation for metformin hydrochloride and for Content uniformity for glyburide.
Related compounds—
glyburide—
Diluent, Mobile phase, and Chromatographic system— Prepare as directed in the Assay for glyburide.
Standard stock solution— Prepare as directed for the Standard preparation in the Assay for glyburide.
Standard solution— Transfer 1.0 mL of the Standard stock solution to a 100-mL volumetric flask, dilute with Diluent to volume, and mix.
Test solution— Use the Assay preparation, prepared as directed in the Assay for glyburide.
Procedure— Separately inject equal volumes (about 100 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure all of the peak responses. Calculate the percentage of glyburide related compound A in the portion of Tablets taken by the formula:
100CFVD(ri / rS)/NL
in which C is the concentration, in mg per mL, of glyburide in the Standard solution; F is the relative response factor of glyburide related compound A and is equal to 0.8; V is the volume in which the sample is dissolved to prepare the Test solution; D is any further dilution of the sample; ri is the peak response for glyburide related compound A in the Test solution; rS is the peak response for glyburide in the Standard solution; N is the number of Tablets taken to prepare the Test solution; and L is the glyburide label claim in mg per Tablet: not more than 1.0% is found.
Calculate the percentage of any other impurity in the portion of Tablets taken by the formula:
100CVD(ri / rS)/NL
in which ri is the peak response for each impurity obtained from the Test solution; and the other terms are as defined above: not more than 0.2% of any other impurity is found; and the sum of all impurities, excluding glyburide related compound A, is not more than 0.50%. Disregard any peak less than 0.05%, and disregard any peak observed in the blank.
Chromatographic purity—
metformin hydrochloride—
Mobile phase and Chromatographic system— Prepare as directed in the Assay for metformin hydrochloride.
Test solution— Use the Assay preparation, prepared as directed in the Assay for metformin hydrochloride.
Procedure— Inject a volume (about 5 µL) of the Test solution into the chromatograph, record the chromatogram, and measure all of the peak responses. Calculate the percentage of each impurity in the portion of Tablets taken by the formula:
100(ri / rs)
in which ri is the peak response for each impurity; and rs is the sum of the responses of all the peaks: not more than 0.1% of any individual impurity is found; and not more than 0.5% of total impurities is found. Disregard any peak less than 0.05%, and disregard any peak observed in the blank.
Assay for glyburide—
Diluent— Use a mixture of acetonitrile and water (50:50).
Ammonium phosphate buffer solution— Dissolve 28.8 g of monobasic ammonium phosphate in water, and dilute with water to 1000 mL.
Mobile phase— Prepare a filtered and degassed mixture of Ammonium phosphate buffer solution and acetonitrile (60:40), and adjust with 1 N sodium hydroxide solution to a pH of 5.3. Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard preparation— Transfer an accurately weighed quantity of USP Glyburide RS to a suitable volumetric flask. Dissolve first in acetonitrile, using 50% of the final volume, then dilute with water to volume, and mix, to obtain a solution having a known concentration of about 0.25 mg of glyburide per mL. Dilute quantitatively, and stepwise if necessary, with Diluent to obtain a solution having a known concentration of about 0.025 mg per mL.
System suitability intermediate preparation— Prepare a solution of USP Glyburide Related Compound A RS in Diluent having a concentration of 0.025 mg per mL. Transfer 50 µL of this solution to a 50-mL volumetric flask, and dilute with Standard preparation to volume.
System suitability preparation— Transfer an accurately weighed quantity of USP Metformin Hydrochloride RS, and dilute quantitatively with the System suitability intermediate preparation to obtain a solution having a known concentration of about 5.0 mg per mL.
Assay preparation— Dissolve not fewer than 5 Tablets in Diluent by stirring with a magnetic stirring bar for at least 1 hour. Dilute accurately, and stepwise if necessary, to obtain a solution having a glyburide concentration of approximately 0.025 mg per mL, based on the label claim. Centrifuge a portion of this solution at 3000 rpm for 10 minutes, and use the clear supernatant. [note—Retain a portion of the solution for the Assay for metformin hydrochloride.]
Chromatographic system (see Chromatography 621) The liquid chromatograph is equipped with a 230-nm detector and a 4.6-mm × 15-cm column that contains 5-µm packing L7. The flow rate is about 1.2 mL per minute. The column temperature is maintained at 40. Chromatograph the System suitability preparation, and record the peak responses as directed for Procedure: for the peak due to glyburide, the capacity factor, k¢, is not less than 7; the column efficiency is not less than 3000 theoretical plates; and the relative standard deviation for replicate injections is not more than 1.5%. For the peak due to glyburide related compound A, the relative retention time is approximately 0.30 with respect to glyburide; and the relative standard deviation for replicate injections is not more than 10%.
Procedure— Separately inject equal volumes (about 100 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms for about 1.25 times the retention time of the glyburide peak, and measure the responses for the major peaks. Calculate the quantity, in mg per Tablet, of glyburide (C23H28ClN3O5S) by the formula:
CVD(rU / rS )/N
in which C is the concentration, in mg per mL, of USP Glyburide RS in the Standard preparation; V is the volume, in mL, used to prepare the Assay preparation; D is the dilution factor of the Assay preparation; rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively; and N is the number of Tablets used to prepare the Assay preparation.
Assay for metformin hydrochloride—
Diluent— Use a 2.5% solution of acetonitrile in water.
Buffer solution— Transfer 1.0 g each of sodium heptanesulfonate and sodium chloride to a 2000-mL volumetric flask, add 1800 mL of water, and mix. Adjust with 0.06 M phosphoric acid to a pH of 3.85, and dilute with water to volume.
Mobile phase— Prepare a filtered and degassed mixture of Buffer solution and acetonitrile (90:10). Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard preparation— Dissolve an accurately weighed quantity of USP Metformin Hydrochloride RS in Diluent, and dilute quantitatively, and stepwise if necessary, with Diluent to obtain a solution having a known concentration of about 0.25 mg per mL. Use sonication if necessary to achieve a complete dissolution.
System suitability preparation— Dissolve suitable quantities of USP Metformin Related Compound B RS and USP Metformin Related Compound C RS in Diluent to obtain a solution containing about 25 µg per mL of each. Pipet 0.5 mL of this solution into a 50-mL volumetric flask, and dilute with the Standard preparation to volume.
Assay preparation— Quantitatively dilute a portion of the Assay preparation, obtained as directed for Assay for glyburide, with water to obtain a solution having an expected concentration of about 0.25 mg of metformin hydrochloride per mL, based on the label claim.
Chromatographic system (see Chromatography 621) The liquid chromatograph is equipped with a 218-nm detector and a 3.9-mm × 30-cm column that contains 10-µm packing L1. The flow rate is about 1.0 mL per minute. The column temperature is maintained at 30. Chromatograph the System suitability preparation, and record the peak responses as directed for Procedure: the relative retention times are about 0.86 for metformin related compound B, 1.0 for metformin, and about 2.1 to 2.3 for metformin related compound C [note—This impurity can have a variable retention time]; the resolution, R, between metformin related compound B and metformin is not less than 1.5; the tailing factor for the metformin peak is not less than 0.8 and not more than 2.0; and the relative standard deviation for replicate injections is not more than 1.5% for the metformin peak and not more than 10% for each of the peaks due to metformin related compound B and metformin related compound C.
Procedure— Separately inject equal volumes (about 5 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms until after the elution locus of metformin related compound C, and measure the responses for the major peaks. Calculate the quantity, in mg per Tablet, of metformin hydrochloride (C4H11N5·HCl) by the formula:
CVD(rU / rS )/N
in which C is the concentration, in mg per mL, of USP Metformin Hydrochloride RS in the Standard preparation; V is the volume, in mL, used to prepare the Assay preparation; D is the dilution factor of the Assay preparation; rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively; and N is the number of Tablets used to prepare the Assay preparation.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Elena Gonikberg, Ph.D.
Senior Scientist
1-301-816-8251
(MDGRE05) Monograph Development-Gastrointestinal Renal and Endocrine
Reference Standards Lili Wang, Technical Services Scientist
1-301-816-8129
RSTech@usp.org
711 Margareth R.C. Marques, Ph.D.
Senior Scientist
1-301-816-8106
(BPC05) Biopharmaceutics05
USP32–NF27 Page 2511
Pharmacopeial Forum: Volume No. 34(5) Page 1163
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.