Oxytetracycline Tablets
Action and use
Tetracycline antibacterial.
Definition
Oxytetracycline Tablets contain Oxytetracycline Dihydrate. They are coated.
Content of oxytetracycline dihydrate, C22H24N2O9,2H2O
95.0 to 110.0% of the stated amount.
Identification
6 volumes of water, 35 volumes of methanol and 59 volumes of dichloromethane.
The test is not valid unless the chromatogram obtained with solution (3) shows two clearly separated spots.
The principal spot in the chromatogram obtained with solution (1) corresponds in position, colour and size to that in the chromatogram obtained with solution (2).
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 measure the absorbance of the filtered sample, suitably diluted with the dissolution medium if necessary, at the maximum at 353 nm, Appendix II B, using 0.1m hydrochloric acid in the reference cell.
Calculate the total content of oxytetracycline dihydrate, C22H24N2O9,2H2O, in the medium taking 282 as the value of A(1%, 1 cm) at the maximum at 353 nm.
Light-absorbing impurities
Wash five tablets with water or chloroform until any coloured coating is removed, dry with filter paper and powder. Dissolve portions of the powder as completely as possible in sufficient of a mixture of 1 volume of 1m hydrochloric acid and 99 volumes of methanol to produce two solutions of Oxytetracycline Dihydrate containing (1) 0.20% w/v and (2) 1.0% w/v and filter each solution. The absorbance of the filtrate obtained from solution (1) at 430 nm is not more than 0.50 and the absorbance of the filtrate obtained from solution (2) at 490 nm is not more than 0.40, Appendix II B.
Assay
Weigh and powder 20 tablets. Carry out the method for liquid chromatography, Appendix III D, using the following solutions in 0.01m hydrochloric acid.
To 50.0 g of 2-methyl-propan-2-ol add 200 mL of water, 60 mL of 0.33m phosphate buffer pH 7.5, 50 mL of a 1.0% w/v solution of tetrabutylammonium hydrogen sulfate previously adjusted to pH 7.5 with 2m sodium hydroxide and 10 mL of a 0.04% w/v solution of disodium edetate previously adjusted to pH 7.5 with 2m sodium hydroxide and dilute to 1 litre with water.
The Assay is not valid unless, in the chromatogram obtained with solution (5):
the resolution factor between the first peak (4-epioxytetracycline) and the second peak (oxytetracycline) is at least 4.0;
the resolution factor between the second peak and the third peak (tetracycline) is at least 5.0 (if necessary, reduce the content of 2-methylpropan-2-ol in the mobile phase to increase the resolution);
the symmetry factor of the peak due to oxytetracycline is not more than 1.25.
Calculate the content of C22H24N2O9,2H2O in the tablets using the declared content of C22H24N2O9 in oxytetracycline BPCRS. Each mg of C22H24N2O9 is equivalent to 1.078 mg of C22H24N2O9,2H2O.