Oxytetracycline Capsules

General Notices

Action and use

Tetracycline antibacterial.

Definition

Oxytetracycline Capsules contain Oxytetracycline Hydrochloride.

The capsules comply with the requirements stated under Capsules and with the following requirements.

Content of oxytetracycline hydrochloride, C22H24N2O9,HCl

95.0 to 110.0% of the stated amount.

Identification

A. Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions.
(1) Extract a quantity of the contents of the capsules containing 10 mg of Oxytetracycline Hydrochloride with 20 mL of methanol, centrifuge and use the supernatant liquid.
(2) Dissolve 5 mg of oxytetracycline hydrochloride BPCRS in sufficient methanol to produce 10 mL.
(3) Dissolve 5 mg of oxytetracycline hydrochloride BPCRS and 5 mg of demeclocycline hydrochloride BPCRS in sufficient methanol to produce 10 mL.
chromatographic conditions
(a) Use a silica gel precoated plate (Merck silica gel 60 plates are suitable). Adjust the pH of a 10% w/v solution of disodium edetate to 7.0 with 10m sodium hydroxide and spray the solution evenly onto the plate (about 10 mL for a plate 100 mm × 200 mm). Allow the plate to dry in a horizontal position for at least 1 hour. Before use, dry the plate at 110° for 1 hour.
(b) Use the mobile phase as described below.
(c) Apply 1 µL of each solution.
(d) Develop the plate to 15 cm.
(e) After removal of the plate, dry it in a current of air and examine under ultraviolet light (365 nm).
mobile phase

6 volumes of water, 35 volumes of methanol and 59 volumes of dichloromethane.

system suitability

The test is not valid unless the chromatogram obtained with solution (3) shows two clearly separated spots.

confirmation

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).

B. To 0.5 mg of the contents of the capsules add 2 mL of sulfuric acid; a deep crimson colour is produced. Add 1 mL of water; the colour changes to yellow.
C. The contents of the capsules yield the reactions characteristic of chlorides, Appendix VI.

Tests

Dissolution

Comply with the requirements for Monographs of the British Pharmacopoeia in the dissolution test for tablets and capsules, Appendix XII B1.

test conditions
(a) Use Apparatus 1, rotating the basket at 100 revolutions per minute.
(b) Use 900 mL of 0.1m hydrochloric acid, at a temperature of 37°, as the medium.
procedure

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.

determination of content

Calculate the total content of oxytetracycline hydrochloride, C22H24N2O9,HCl, in the medium taking 282 as the value of A(1%, 1 cm) at the maximum at 353 nm.

Light-absorbing impurities

Dissolve a portion of the mixed contents of five capsules 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 Hydrochloride 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 0.75, Appendix II B, calculated with reference to the dried capsule contents. The absorbance of the filtrate obtained from solution (2) at 490 nm is not more than 0.40, calculated with reference to the dried capsule contents.

Loss on drying

When dried at 60° at a pressure not exceeding 0.7 kPa for 3 hours, the contents of the capsules lose not more than 5.0% of their weight. Use 1 g.

Assay

Carry out the method for liquid chromatography, Appendix III D, using the following solutions in 0.1m methanolic hydrochloric acid prepared by diluting 1 volume of 1m hydrochloric acid to 10 volumes with methanol.

(1) Shake, with the aid of ultrasound, a quantity of the mixed contents of 20 capsules containing 0.1 g of Oxytetracycline Hydrochloride with 80 mL of the 0.1m methanolic hydrochloric acid. Dilute to 100 mL, centrifuge and further dilute 1 volume of the clear supernatant liquid to 20 volumes with the same solvent.
(2) 0.005% w/v of oxytetracycline BPCRS.
(3) 0.1% w/v of 4-epioxytetracycline EPCRS.
(4) 0.1% w/v of tetracycline hydrochloride BPCRS.
(5) Dilute a mixture containing 1.5 mL of a 0.1% w/v solution of oxytetracycline BPCRS in the 0.1m methanolic hydrochloric acid, 1 mL of solution (3) and 3 mL of solution (4) to 25 mL with the same solvent.
chromatographic conditions
(a) Use a stainless steel column (25 cm × 4.6 mm) packed with styrene-divinylbenzene copolymer (8 to 10 µm) (Polymer Laboratories, PLRP-S 100A, is suitable).
(b) Use isocratic elution and the mobile phase described below.
(c) Use a flow rate of 1 ml per minute.
(d) Use a column temperature of 60°.
(e) Use a detection wavelength of 254 nm.
(f) Inject 20 µL of each solution.
mobile phase

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.

system suitability

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.

determination of content

Calculate the content of C22H24N2O9,HCl in the capsules using the declared content of C22H24N2O9 in oxytetracycline BPCRS. Each mg of C22H24N2O9 is equivalent to 1.079 mg of C22H24N2O9,HCl.