Clindamycin Capsules

General Notices

Action and use

Lincosamide antibacterial.

Definition

Clindamycin Capsules contain Clindamycin Hydrochloride.

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

Content of clindamycin, C18H33ClN2O5S

90.0 to 110.0% of the stated amount.

Identification

A. Shake a quantity of the contents of the capsules containing the equivalent of 30 mg of clindamycin with 15 mL of chloroform, filter and evaporate the filtrate to dryness. The infrared absorption spectrum of the residue, Appendix II A, is concordant with the reference spectrum of clindamycin hydrochloride (RS 064).
B. In the Assay, the chromatogram obtained with solution (1) shows a peak with the same retention time as the principal peak in the chromatogram obtained with solution (2).

Tests

Related substances

Carry out the method for liquid chromatography, Appendix III D, using the following solutions.

(1) Shake a quantity of the contents of the capsules containing the equivalent of 50 mg of clindamycin with 50 mL of the mobile phase for 15 minutes and filter (Whatman GF/C filter is suitable).
(2) Dilute 1 volume of solution (1) to 50 volumes with the mobile phase.
(3) 0.1% w/v of clindamycin hydrochloride EPCRS in the mobile phase.
chromatographic conditions
(a) Use a stainless steel column (25 cm × 4.6 mm) packed with octadecylsilyl silica gel for chromatography (5 µm) (Hypersil BDS 5 µm is suitable).
(b) Use isocratic elution and the mobile phase described below.
(c) Use a flow rate of 1 mL per minute.
(d) Use an ambient column temperature.
(e) Use a detection wavelength of 210 nm.
(f) Inject 20 µl of each solution.
(g) For solution (1), allow the chromatography to proceed for at least twice the retention time of the principal peak.
mobile phase

45 volumes of acetonitrile and 55 volumes of a 0.68% w/v solution of potassium dihydrogen orthophosphate adjusted to pH 7.5 with a 25% w/v solution of potassium hydroxide.

When the chromatograms are recorded under the prescribed conditions the retention time of clindamycin is about 10 minutes.

system suitability

The test is not valid unless the chromatogram obtained with solution (3) shows peaks with retention times relative to clindamycin of about 0.4 [Ph Eur impurity A (lincomycin)], about 0.65 [Ph Eur impurity B (clindamycin B)] and about 0.8 [Ph Eur impurity C (7-epiclindamycin)].

limits

In the chromatogram obtained with solution (1):

the area of any peak corresponding to impurity B is not greater than the area of the principal peak in the chromatogram obtained with solution (2) (2%);

the area of any peak corresponding to impurity C is not greater than twice the area of the principal peak in the chromatogram obtained with solution (2) (4%);

the area of any other secondary peak is not greater than half the area of the principal peak in the chromatogram obtained with solution (2) (1%);

the sum of the areas of all the secondary peaks is not greater than 3 times the area of the principal peak in the chromatogram obtained with solution (2) (6%).

Disregard any peak with an area less than 0.025 times the area of the principal peak in the chromatogram obtained with solution (2) (0.05%).

Water

The contents of the capsules contain not more than 7.0% w/w of water, Appendix IX C. Use 1 g.

Assay

Carry out the method for liquid chromatography, Appendix III D, using the following solutions.

(1) Shake a quantity of the mixed contents of 20 capsules containing the equivalent of 50 mg of clindamycin with 50 mL of the mobile phase for 15 minutes and filter (Whatman GF/C filter is suitable).
(2) 0.11% w/v of clindamycin hydrochloride EPCRS in the mobile phase.
chromatographic conditions

The chromatographic conditions described under Related substances may be used.

determination of content

Calculate the content of C18H33ClN2O5S in the capsules using the declared content of C18H33ClN2O5S,HCl in clindamycin hydrochloride EPCRS. Each mg of C18H33ClN2O5S,HCl is equivalent to 0.9209 mg of C18H33ClN2O5S.

Labelling

The quantity of active ingredient is stated in terms of the equivalent amount of clindamycin.

Impurities

The impurities limited by the requirements of this monograph include those listed under Clindamycin Hydrochloride.