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Prazosin Hydrochloride Capsules
» Prazosin Hydrochloride Capsules contain an amount of C19H21N5O4·HCl equivalent to not less than 90.0 percent and not more than 110.0 percent of the labeled amount of prazosin (C19H21N5O4).
Caution—Care should be taken to prevent inhaling particles of Prazosin Hydrochloride and to prevent its contacting any part of the body.
Packaging and storage— Preserve in well-closed, light-resistant containers.
Identification— To a portion of the contents of Capsules, equivalent to about 10 mg of prazosin, add 20 mL of a mixture of chloroform and methanol (1:1), shake by mechanical means for 10 minutes, and centrifuge. Apply as separate 7.5-cm streaks 100 µL of this solution and 100 µL of a Standard solution of USP Prazosin Hydrochloride RS in a mixture of chloroform and methanol (1:1) containing about 0.5 mg per mL to a suitable thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture. Allow the streaks to dry, and develop the chromatogram in a solvent system consisting of a mixture of ethyl acetate and diethylamine (19:1) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, allow the solvent to evaporate, and view under short-wavelength UV light: prazosin appears as a dark blue band on a yellow-green fluorescent background, and the RF value of the prazosin band obtained from the solution from the Capsule contents corresponds to that obtained from the Standard solution. Spray the plate evenly with a 1 in 50 solution of hydrochloric acid in potassium iodoplatinate TS: the RF value of the principal band obtained from the solution from the Capsule contents corresponds to that obtained from the Standard solution.
Dissolution 711—
Medium: 0.1 N hydrochloric acid containing 3% sodium lauryl sulfate; 900 mL.
Apparatus 1: 100 rpm.
Time: 60 minutes.
Procedure— Determine the amount of C19H21N5O4 dissolved, employing the procedure set forth in the Assay, using a filtered portion of the solution under test as the Assay preparation in comparison with a Standard solution having a known concentration of USP Prazosin Hydrochloride RS in the same Medium.
Tolerances— Not less than 75% (Q) of the labeled amount of C19H21N5O4 is dissolved in 60 minutes.
Uniformity of dosage units 905: meet the requirements.
Procedure for content uniformity— Transfer the contents of a Capsule to a 100-mL volumetric flask, add 50 mL of 0.01 N methanolic hydrochloric acid containing 30% water, shake by mechanical means for 15 minutes, adjust with the same solvent to volume, and mix. Filter through a membrane filter having a porosity of 1.2 µm and dilute, if necessary, a portion of the filtrate with the same solvent to a concentration of about 10 µg of prazosin per mL. Prepare a Standard solution of USP Prazosin Hydrochloride RS in the same solvent having a known concentration of about 11 µg per mL. Concomitantly determine the absorbances of the solution from the Capsule contents and the Standard solution in 1-cm cells at the wavelength of maximum absorbance at about 330 nm, with a suitable spectrophotometer, using the solvent as the blank. Calculate the quantity, in mg, of prazosin (C19H21N5O4) in the Capsule taken by the formula:
(383.40/419.86)(0.001DC)(AU / AS),
in which 383.40 and 419.86 are the molecular weights of prazosin and prazosin hydrochloride, respectively; D is the dilution factor for the Capsule contents; C is the concentration, in µg per mL, of USP Prazosin Hydrochloride RS, calculated on the anhydrous basis, in the Standard solution; and AU and AS are the absorbances of the solution from the Capsule contents and the Standard solution, respectively.
Residual solvents 467: meet the requirements.
(Official January 1, 2007)
Assay—
Mobile phase, Chromatographic system, and Procedure— Proceed as directed in the Assay under Prazosin Hydrochloride.
Acid–methanol solution— To 300 mL of water in a 1000-mL volumetric flask, add 0.85 mL of hydrochloric acid, dilute with methanol to volume, and mix. Transfer 300 mL of this solution to a 500-mL volumetric flask, dilute with methanol to volume, and mix.
Standard preparation— Prepare a solution of USP Prazosin Hydrochloride RS in Acid–methanol solution having a known concentration of about 0.2 mg per mL. Pipet 5 mL of this solution into a 100-mL volumetric flask, add 45.0 mL of Acid–methanol solution, dilute with methanol to volume, and mix.
Assay preparation— Remove, as completely as possible, the contents of not less than 20 Capsules, and weigh. Transfer a quantity of the contents, accurately weighed, equivalent to about 1 mg of prazosin hydrochloride, to a glass-stoppered flask containing 50.0 mL of Acid–methanol solution, and shake by mechanical means for 30 minutes. Place the flask in an ultrasonic bath for 30 minutes, cool to room temperature, and filter the contents through a membrane filter (5 µm or finer porosity). Transfer 25.0 mL of the filtrate to a 50-mL volumetric flask, dilute with methanol to volume, and mix.
Procedure— Proceed as directed for Procedure in the Assay under Prazosin Hydrochloride. Calculate the quantity, in mg, of prazosin (C19H21N5O4) in the portion of the contents of Capsules taken by the formula:
(383.40/419.86)(0.1C)(rU / rS),
in which 383.40 and 419.86 are the molecular weights of prazosin and prazosin hydrochloride, respectively; C is the concentration, in µg per mL, of USP Prazosin Hydrochloride RS, calculated on the anhydrous basis, in the Standard preparation; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.
Auxiliary Information— Staff Liaison : Andrzej Wilk, Ph.D., Senior Scientific Associate
Expert Committee : (MDCV05) Monograph Development-Cardiovascular
USP29–NF24 Page 1785
Pharmacopeial Forum : Volume No. 28(2) Page 346
Phone Number : 1-301-816-8305