Ginkgo Capsules are prepared with Powdered Ginkgo Extract and contain, in the labeled amount of Powdered Extract, NLT 22.0% and NMT 27.0% of flavonol glycosides and NLT 5.4% and NMT 12.0% of terpene lactones, calculated as the sum of bilobalide (C15H18O8), ginkgolide A (C20H24O9), ginkgolide B (C20H24O10), and ginkgolide C (C20H24O11).
Change to read:• A. HPLC: In the test for Content of Flavonol Glycosides, the retention times of the peaks for quercetin, isorhamnetin, and kaempferol of the Sample solution correspond to those of the Standard solution. In the chromatogram of the Sample solution, the ratio of the kaempferol peak to the quercetin peak is NLT 0.7, and the peak for isorhamnetin is NLT 0.1 times the size of the quercetin peak.USP35
• B. HPLC: The retention times of the peaks for bilobalide, ginkgolide A, ginkgolide B, and ginkgolide C of the Sample solution correspond to those of the Standard solutions, as obtained in the test for Content of Terpene Lactones.
Change to read:• Content of Flavonol Glycosides
Mobile phase: Methanol, water, and phosphoric acid (100:100:1)
Standard solution A: 0.2 mg/mL of USP Quercetin RS in methanol
Standard solution B: 0.2 mg/mL of USP Kaempferol RS in methanol
Standard solution C: 0.05 mg/mL of USP Isorhamnetin RS in methanol
Sample solution: Weigh and finely powder the contents of NLT 20 Capsules. Transfer an accurately weighed quantity of the powder, equivalent to about 50 mg of flavonol glycosides, to a 50-mL volumetric flask. Add 20 mL of methanol, and sonicate for 3 min. Add 20 mL of 1.5 N hydrochloric acid, and sonicate again for 10 min. Allow to cool to room temperature, and dilute with methanol to volume. Centrifuge, and transfer a portion of the clear supernatant to a rubber-capped, low-actinic glass vial. Heat in a steam bath for 25 min, and cool to room temperature in an ice bath.
Detector: UV 370 nm
Column: 4.6-mm × 25-cm; packing L1
Flow rate: 1.5 mL/min
Injection size: 20 µL
Samples: Standard solution A, Standard solution B, and Standard solution C
[NoteThe relative retention times for quercetin, kaempferol, and isorhamnetin are about 1.0, 1.8, and 2.0, respectively; Standard solution A, Standard solution B, and Standard solution C. ]
Relative standard deviation: NMT 2.0% determined from the quercetin peak in repeated injections, Standard solution A
Samples: Standard solution A, Standard solution B, Standard solution C, and Sample solution
Calculate the quantity, in mg, of each flavonol glycoside in the portion of Capsules taken:
Result = (rU/rS) × CS × F × 50
Calculate the total quantity, in mg, of flavonol glycosides in the portion of Capsules taken by adding the individual quantities calculated. Calculate the total quantity, in mg, of flavonol glycosides per Capsule and the percentage of flavonol glycosides in the labeled amount of Powdered Extract.
Acceptance criteria: 22.0%27.0% of flavonol glycosidesUSP35
• Content of Terpene Lactones
Solvent: Methanol and water (9:1)
Buffer solution: Dissolve 1.19 g of dibasic sodium phosphate and 8.25 g of monobasic potassium phosphate in 1000 mL of water, and adjust to a pH of 5.8.
Diluent: Methanol and water (1:1)
Solution A: Water
Solution B: Methanol
Mobile phase: See Table 1.
Standard solutions: Dissolve accurately weighed quantities of USP Ginkgo Terpene Lactones RS in Diluent, sonicate for a few min, and dilute with Diluent to obtain solutions with known concentrations of 0.25, 0.5, 1.0, 2.0, and 4.0 mg/mL. Pass through a filter of 0.45-µm or finer pore size.
Sample solution: Weigh and finely powder the contents of NLT 20 Capsules. Transfer an accurately weighed quantity of the powder, equivalent to about 120 mg of ginkgo extract, to a 30-mL glass centrifuge tube with a screw cap and PTFE gasket. Add 10.0 mL of Solvent, seal the tube, and mix well on a vortex mixer. Heat in a water bath at 90 for 30 min. Mix the hot suspension on a vortex mixer, and repeat the heating at 90 for 30 min. Cool, centrifuge, transfer the supernatant to a flask, and return the residue to the glass tube. Repeat the extraction two more times, each time using 10.0 mL of Solvent. Combine the extracts, allow them to cool to room temperature, and evaporate to dryness under vacuum in a water bath maintained at 50. Add 10 mL of Buffer solution to the residue, and sonicate for 5 min. Quantitatively transfer the solution to a glass chromatographic tube filled with chromatographic siliceous earth capable of holding 20 mL of aqueous phase.1 Rinse the beaker with two 5-mL portions of Buffer solution, and transfer the washings to the column. [NoteDo not exceed 20 mL of total aqueous phase or the holding capacity of the chromatographic tube. ] Allow the Buffer solution to be absorbed into the column. After 15 min, elute the column with 100 mL of ethyl acetate, collect the ethyl acetate solution, and evaporate to dryness under vacuum in a water bath maintained at 50. Dissolve the residue in 20.0 mL of Diluent.
Detector: Evaporative light-scattering. [NoteThe parameters of the detector are adjusted to achieve the best signal-to-noise ratio, according to manufacturer recommendations. ]
Column: 4.6-mm × 25-cm; packing L1
Column temperature: 25 ± 1
Flow rate: 1 mL/min
Injection size: 15 µL
Samples: Standard solutions
Chromatogram similarity: The chromatograms from the Standard solutions are similar to the reference chromatogram provided with the lot of USP Ginkgo Terpene Lactones RS being used.
Relative standard deviation: NMT 2.0% determined from the bilobalide peak in repeated injections
Correlation coefficient: NLT 0.995 for the regression line as determined in the Analysis
Samples: Standard solutions and Sample solution
Record the chromatograms, and identify the peaks of the relevant analytes in the chromatogram of the Standard solutions by comparison with the reference chromatogram being used. Measure the areas of the analyte peaks. Plot the logarithms of the relevant peak responses versus the logarithms of concentrations, in mg/mL, of each analyte obtained from the Standard solutions, and determine the regression line using a least-squares analysis.
From the graphs, determine the concentration, C, in mg/mL, of the relevant analyte in the Sample solution.
Separately calculate the quantities, in mg, of bilobalide (C15H18O8), ginkgolide A (C20H24O9), ginkgolide B (C20H24O10), and ginkgolide C (C20H24O11) in the portion of Capsules taken:
Result = C × 20
Calculate the total quantity of terpene lactones in the portion of Capsules taken by adding the quantities calculated for each analyte. Calculate the total quantity, in mg, of terpene lactones per Capsule and the percentage of terpene lactones in the labeled amount of Powdered Extract.
Acceptance criteria: 5.4%12.0% of terpene lactones, calculated as the sum of bilobalide, ginkgolide A, ginkgolide B, and ginkgolide C
• Disintegration and Dissolution 2040: Meet the requirements for Dissolution
Medium: 0.1 N hydrochloric acid; 500 mL
Apparatus 2: 75 rpm
Time: 45 min
Standard solutions: Proceed as directed in the test for Content of Terpene Lactones.
Sample solution: Combine 25-mL portions of the solution under test from each of the six dissolution vessels in a separation funnel. Extract with four 50-mL portions of ethyl acetate. Combine the extracts and evaporate in vacuum to dryness. Dissolve the residue with sonication in 5.0 mL of a mixture of water and methanol (1:1).
Analysis: Proceed as directed in the test for Content of Terpene Lactones to determine the concentration, C, in mg/mL, of ginkgolide B in the Sample solution.
Calculate the percentage of ginkgolide B dissolved:
Result = (C/3) × G × 5000
Tolerances: NLT 75% of the content of ginkgolide B is dissolved.
• Weight Variation 2091: Meet the requirements
Add the following:• Microbial Enumeration Tests 2021: The total aerobic microbial count does not exceed 104 cfu/g, and the total combined molds and yeasts count does not exceed 103 cfu/g.USP35
Add the following:• Absence of Specified Microorganisms 2022: Meet the requirements of the tests for absence of Salmonella species and Escherichia coliUSP35
• Packaging and Storage: Preserve in tight, light-resistant containers, and store at room temperature.
• Labeling: The label states the Latin binomial and, following the official name, the article used to prepare the Capsules. Label the Capsules to indicate the amount, in mg, of Powdered Ginkgo Extract per Capsule.
Change to read:• USP Reference Standards 11
USP Isorhamnetin RS
USP Kaempferol RSUSP35
USP Quercetin RS
1 Suitable commercially available material is Extrelut® NT 20 from E Merck Science.
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USP35NF30 Page 1329Pharmacopeial Forum: Volume No. 36(6) Page 1609