Nifedipine Extended-release Capsules
Nifedipine Extended-release Capsules contain not less than 93.0% and not more than 107.0% of the labeled amount of nifedipine (C17H18N2O6: 346.33).
Method of preparation
Prepare as directed under Capsules, with Nifedipine.
Identification
Conduct this procedure without exposure to light, using light-resistant vessels. Take out the content of Nifedipine Extended-release Capsules, and powder. To an amount of the powder, equivalent to 3 mg of Nifedipine, add 100 mL of methanol, shake for 15 minutes, and centrifuge. Determine the absorption spectrum of the supernatant liquid so obtained as directed under Ultraviolet-visible Spectrophotometry <2.24>: it exhibits a broad absorption maximum between 335 nm and 356 nm.
Uniformity of dosage units <6.02>
Perform the test according to the following method: it meets the requirement of the Content uniformity test.
Conduct this procedure without exposure to light, using light-resistant vessels. To the total content of 1 capsule of Nifedipine Extended-release Capsules, add 50 mL of a mixture of methanol and water (9:1), agitate for 15 minutes with the aid of ultrasonic waves with occasional shaking, and shake for further 15 minutes. Then, add methanol to make exactly V mL so that each mL contains about 0.1 mg of nifedipine (C17H18N2O6). Filter this solution through a membrane filter with a pore size not exceeding 0.45 µm. Discard the first 10 mL of the filtrate, pipet 5 mL of the subsequent filtrate, add methanol to make exactly 10 mL, and use this solution as the sample solution.
Separately, weigh accurately about 50 mg of nifedipine for assay, previously dried at 105oC for 2 hours, and dissolve in methanol to make exactly 50 mL. Pipet 5 mL of this solution, add methanol to make exactly 100 mL, and use this solution as the standard solution. Then, proceed as directed in the Assay.
Amount (mg) of nifedipine (C17H18N2O6)
＝ MS × AT/AS × V/500
MS: Amount (mg) of nifedipine for assay taken
Dissolution
Being specified separately when the drug is granted approval based on the Law.
Assay
Conduct this procedure without exposure to light, using light-resistant vessels. Take out the contents of not less than 20 Nifedipine Extended-release Capsules, weigh accurately the mass of the contents, and powder. Weigh accurately a portion of the powder, equivalent to about 10 mg of nifedipine (C17H18N2O6), add 50mL of a mixture of methanol and water (9:1), shake vigorously for 15 minutes, and add methanol to make exactly 100 mL. Filter this solution through a membrane filter with a pore size not exceeding 0.45 µm. Discard the first 10 mL of the filtrate, pipet 5 mL of the subsequent filtrate, add methanol to make exactly 10 mL, and use this solution as the sample solution.
Separately, weigh accurately about 50 mg of nifedipine for assay, previously dried at 105oC for 2 hours, and dissolve in methanol to make exactly 50 mL. Pipet 5 mL of this solution, add methanol to make exactly 100 mL, and use this solution as the standard solution. Perform the test with exactly 10 µL each of the sample solution and standard solution as directed under Liquid Chromatography <2.01> according to the following conditions, and determine the peak areas, AT and AS, of nifedipine in each solution.
Amount (mg) of nifedipine (C17H18N2O6)
＝ MS × AT/AS × 1/5
MS: Amount (mg) of nifedipine for assay taken
Operating conditions—
Detector: An ultraviolet absorption photometer (wavelength: 230 nm).
Column: A stainless steel column 4.6 mm in inside diameter and 15 cm in length, packed with octadecylsilanized silicagel for liquid chromatography (5 µm in particle diameter). Column temperature: A constant temperature of about 40oC.
Mobile phase: Adjust to pH 6.1 of a mixture of methanol and diluted 0.05 mol/L disodium hydrogen phosphate TS (1 in 5) (11:9) with phosphoric acid.
Flow rate: Adjust so that the retention time of nifedipine is about 6 minutes.
System suitability—
System performance: When the procedure is run with 10 µL of the standard solution under the above operating conditions, the number of theoretical plates and the symmetry factor of the peak of nifedipine are not less than 4000 and not more than 1.2, respectively.
System repeatability: When the test is repeated 6 times with 10 µL of the standard solution under the above operating conditions, the relative standard deviation of the peak area of nifedipine is not more than 1.0%.
Containers and storage
Containers—Tight containers.
Storage—Light-resistant.
THE JAPANESE PHARMACOPOEIA
SEVENTEENTH EDITION
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