Identification—
Shake a suitable quantity of finely powdered Capsule contents with methanol to obtain a solution containing the equivalent of 1 mg of doxycycline per mL, and filter. Using the filtrate as the
Test Solution, proceed as directed for
Method II under
Identification—Tetracyclines 
193
.
Drug release, Method B 724—
Acid stage—
[NOTE—Conduct the test by transferring the contents of each Capsule to the individual basket units of the apparatus.]
Medium:
0.06 N hydrochloric acid; 900 mL.
Apparatus 1:
50 rpm.
Time:
20 minutes.
Diluting solvent:
0.1 N hydrochloric acid.
Procedure—
Determine the amount of C
22H
24N
2O
8 dissolved from UV absorbances at the wavelength of maximum absorbance at about 345 nm of filtered portions of the solution under test, suitably diluted with
Diluting solvent, in comparison with a Standard solution having a known concentration of about 0.01 mg of
USP Doxycycline Hyclate RS per mL in
Diluting solvent.
Tolerances—Level 1
(6 Capsules tested): No individual value exceeds 50% dissolved. Level 2 (6 Capsules tested: Not more than 2 individual values of 12 tested are greater than 50% dissolved.
Buffer stage—
[NOTE—Conduct this stage of testing on separate specimens, selecting Capsules that were not previously subjected to Acid stage testing and transferring the contents of each Capsule to the individual basket units of the apparatus.]
Apparatus 1:
50 rpm.
Time:
30 minutes.
Diluting solvent:
0.1 N hydrochloric acid.
Procedure—
Determine the amount of C
22H
24N
2O
8 dissolved from UV absorbances at the wavelength of maximum absorbance at about 345 nm of filtered portions of the solution under test, suitably diluted with
Diluting solvent, in comparison with a Standard solution having a known concentration of about 0.01 mg of
USP Doxycycline Hyclate RS per mL in
Diluting solvent.
Tolerances—
Not less than 85% (Q) of the labeled amount of C22H24N2O8 is dissolved in 30 minutes.
Dissolution 711—
Proceed as directed for
Procedure for
Method B under
Apparatus 1 and Apparatus 2, Delayed-Release Dosage Forms.
Acid stage—
[NOTE—Conduct the test by transferring the contents of each Capsule to the individual basket units of the apparatus.
]
Medium:
0.06 N hydrochloric acid; 900 mL.
Apparatus 1:
50 rpm.
Time:
20 minutes.
Diluting solvent:
0.1 N hydrochloric acid.
Procedure—
Determine the amount of C
22H
24N
2O
8 dissolved from UV absorbances at the wavelength of maximum absorbance at about 345 nm on filtered portions of the solution under test, suitably diluted with
Diluting solvent, in comparison with a Standard solution having a known concentration of about 0.01 mg of
USP Doxycycline Hyclate RS per mL in
Diluting solvent.
Tolerances—Level 1
(6 Capsules tested): No individual value exceeds 50% dissolved. Level 2 (6 Capsules tested): Not more than 2 individual values of 12 tested are greater than 50% dissolved.
Buffer stage—
[NOTE—Conduct this stage of testing on separate specimens, selecting Capsules that were not previously subjected to
Acid stage testing and transferring the contents of each Capsule to the individual basket units of the apparatus.
]
Apparatus 1:
50 rpm.
Time:
30 minutes.
Diluting solvent:
0.1 N hydrochloric acid.
Procedure—
Determine the amount of C
22H
24N
2O
8 dissolved from UV absorbances at the wavelength of maximum absorbance at about 345 nm on filtered portions of the solution under test, suitably diluted with
Diluting solvent, in comparison with a Standard solution having a known concentration of about 0.01 mg of
USP Doxycycline Hyclate RS per mL in
Diluting solvent.
Tolerances—
Not less than 85% (Q) of the labeled amount of C22H24N2O8 is dissolved in 30 minutes.
(Official April 1, 2006)
Assay—
Mobile phase, Diluent, Resolution solution, Standard preparation, and Chromatographic system—
Proceed as directed in the
Assay under
Doxycycline Hyclate.
Assay preparation—
Remove, as completely as possible, the contents of not fewer than 20 Capsules, and weigh accurately. Mix the combined contents, and transfer an accurately weighed portion of the powder, equivalent to about 100 mg of doxycycline, to a 100-mL volumetric flask, add about 75 mL of Diluent, sonicate for 5 minutes, shake for 15 minutes, dilute with Diluent to volume, and mix. Pass through a membrane filter having a 0.5-µm or finer porosity.
Procedure—
Proceed as directed for
Procedure in the
Assay under
Doxycycline Hyclate. Calculate the quantity, in mg, of doxycycline (C
22H
24N
2O
8) in the portion of Capsules taken by the formula:
0.1CP(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Doxycycline Hyclate RS in the
Standard preparation;
P is the designated potency, in µg of doxycycline per mg, of
USP Doxycycline Hyclate RS; and
rU and
rS are the peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
