Other requirements—
Where the label states that Clindamycin Phosphate is sterile, it meets the requirements for
Sterility and
Bacterial endotoxins under
Clindamycin for Injection. Where the label states that
Clindamycin Phosphate must be subjected to further processing during the preparation of injectable dosage forms, it meets the requirements for
Bacterial endotoxins under
Clindamycin for Injection.
Assay—
Buffer solution—
Add 14 mL of phosphoric acid to 4000 mL of HPLC grade water. Add 10 mL of ammonium hydroxide, and adjust with ammonium hydroxide to a pH of 3.90 ± 0.05.
Organic solution—
Prepare a mixture of acetonitrile and methanol (900:100).
Diluent—
Prepare a degassed mixture of Buffer solution and Organic solution (80:20).
Solution A—
Prepare a degassed mixture of Buffer solution and Organic solution (920:80).
Solution B—
Prepare a degassed mixture of Buffer solution and Organic solution (520:480).
Mobile phase—
Use variable mixtures of
Solution A and
Solution B as directed for
Chromatographic system. Make adjustments if necessary (see
System Suitability under
Chromatography 
621
).
Standard preparation—
Accurately weigh about 22 mg of
USP Clindamycin Phosphate RS. Add 10.0 mL of
Diluent, shake briefly, and sonicate for about 5 minutes to dissolve. Allow to cool to ambient temperature.
Assay preparation—
Accurately weigh about 22 mg of Clindamycin Phosphate. Add 10.0 mL of Diluent, shake briefly, and sonicate for about 5 minutes to dissolve. Allow to cool to ambient temperature.
Chromatographic system—
The liquid chromatograph is equipped with a 214-nm detector and a 4.6-mm × 25-cm column that contains packing L7. The flow rate is about 1.2 mL per minute. Maintain the column at a constant temperature of about 40
. The chromatograph is programmed as follows.
Time
(minutes) |
Solution A
(%) |
Solution B
(%) |
Elution |
| 0 |
95.0 |
5.0 |
equilibrium |
| 0–40 |
95.0®5.0 |
5.0®95.0 |
linear gradient |
| 40–41 |
5.0®95.0 |
95.0®5.0 |
linear gradient |
| 41–46 |
95.0 |
5.0 |
isocratic |
Chromatograph the
Standard preparation, and record the peak areas as directed for
Procedure: the resolution between clindamycin phosphate and its nearest related compound is not less than 1.0, determined as follows. Between the peaks, draw a line perpendicular to the base line at the valley that separates the two peaks. The height of the valley from the base line is not more than 40 percent of the height of the related compound peak. Calculate the resolution,
R, using peak widths at half height. The relative standard deviation determined from the clindamycin phosphate peak is not more than 2.0%.
Procedure—
Separately inject equal volumes (about 25 µL) of the
Standard preparation and the
Assay preparation into the chromatograph, record the chromatograms, and measure the areas of the clindamycin phosphate peaks. Calculate the quantity, in µg, of clindamycin (C
18H
33ClN
2O
5S) in the portion of Clindamycin Phosphate taken by the formula:
(PWS / WU)(rU / rS),
in which
P is the potency, in µg of clindamycin per mg, of
USP Clindamycin Phosphate RS;
WS is the weight, in mg, of
USP Clindamycin Phosphate RS taken to prepare the
Standard preparation; WU is the weight, in mg, of Clindamycin Phosphate taken to prepare the
Assay preparation; and
rU and
rS are the peak areas for clindamycin phosphate obtained from the
Assay preparation and the
Standard preparation, respectively.
-D-galacto-Octopyranoside, methyl 7-chloro-6,7,8-trideoxy-6-[[(1-methyl-4-propyl-2-pyrrolidinyl)carbonyl]amino]-1-thio-, 2-(dihydrogen phosphate), (2S-trans)-.