Rifampicin Capsules
Action and use
Rifamycin antituberculosis drug.
Definition
Rifampicin Capsules contain Rifampicin.
Content of rifampicin, C43H58N4O12
92.5 to 107.5% of the stated amount.
Identification
Tests
Dissolution
Comply with the requirements for Monographs of the British Pharmacopoeia in the dissolution test for tablets and capsules, Appendix XII B1.
After 45 minutes withdraw a 10 mL sample of the medium and filter. Measure the absorbance of the filtered sample, diluted if necessary with 0.1m hydrochloric acid, at the maximum at 336 nm, Appendix II B, using 0.1m hydrochloric acid in the reference cell.
Calculate the total content of rifampicin, C43H58N4O12, in the medium taking 263 as the value of A(1%, 1 cm) at the maximum at 336 nm.
Related substances
Carry out the method for liquid chromatography, Appendix III D, using the following solutions prepared in the solvent mixture described below. To 10 volumes of a 21.01% w/v solution of citric acid add 23 volumes of a 13.61% w/v solution of potassium dihydrogen orthophosphate, 77 volumes of a 17.42% w/v solution of dipotassium hydrogen orthophosphate, 250 volumes of acetonitrile and 640 volumes of water and mix. Prepare the solutions immediately before use.
35 volumes of acetonitrile and 65 volumes of a solution containing 0.1% v/v of orthophosphoric acid, 0.19% w/v of sodium perchlorate, 0.59% w/v of citric acid and 2.09% w/v of potassium dihydrogen orthophosphate.
The test is not valid unless, in the chromatogram obtained with solution (6), the resolution factor between the two principal peaks is at least 4.0. If necessary, adjust the concentration of acetonitrile in the mobile phase.
In the chromatogram obtained with solution (1):
the area of any peak corresponding to rifampicin quinone is not greater than the area of the principal peak in the chromatogram obtained with solution (3) (4%);
the area of any peak corresponding to rifampicin N-oxide is not greater than the area of the principal peak in the chromatogram obtained with solution (4) (1.5%);
the area of any peak corresponding to 3-formylrifamycin SV is not greater than the area of the principal peak in the chromatogram obtained with solution (5) (0.5%);
the area of any other secondary peak is not greater than the area of the principal peak in the chromatogram obtained with solution (2) (1%).
Assay
Shake a quantity of the mixed contents of 20 capsules containing 0.1 g of Rifampicin with 80 mL of methanol, add sufficient methanol to produce 100 mL and filter. Dilute 2 mL of the filtrate to 100 mL with phosphate buffer pH 7.4 and measure the absorbance of the resulting solution at the maximum at 475 nm, Appendix II B. Calculate the content of C43H58N4O12 taking 187 as the value of A(1%, 1 cm) at 475 nm.