Test solution— Transfer a portion of powdered Tablets, equivalent to about 5 mg of oxycodone hydrochloride, to a suitable screw-capped tube, add 5 mL of chloroform, sonicate for about 30 seconds, shake for several minutes, and centrifuge. Use the clear supernatant.

Standard solution: 0.9 mg of USP Oxycodone RS per mL of chloroform.

Application volume: 20 µL.

Developing solvent solution: a mixture of acetone, toluene, ether, and ammonium hydroxide (6:4:1:0.3).

Procedure— Proceed as directed in the chapter. Spray with iodoplatinate TS: the RF value, color, and size of the principal spot obtained from the Test solution correspond to those obtained from the Standard solution; and no other spot is observed.

Medium: simulated gastric fluid (without enzymes); 900 mL.

Apparatus 1: 100 rpm.

Times: 1, 2, 4, 6, and 8 hours, for Tablets labeled to contain 10 mg, 20 mg, or 40 mg; 1, 2, 4, and 6 hours, for Tablets labeled to contain 80 mg.

Standard stock solution— For Tablets labeled to contain 10 mg, transfer about 39.8 mg of USP Oxycodone RS, accurately weighed, into a 100-mL volumetric flask, and dissolve in and dilute with Medium to volume. For Tablets labeled to contain 20 mg, 40 mg, or 80 mg, transfer about 39.8 mg of USP Oxycodone RS, accurately weighed, into a 50-mL volumetric flask, and dissolve in and dilute with Medium to volume.

Working standard solution— Dilute the Standard stock solution with Medium to obtain solutions containing L/900 mg per mL, with L being the oxycodone Tablet label claim, in mg.

Procedure— Determine the amount of oxycodone (C18H21NO4) dissolved from UV absorption at a wavelength of about 226 nm (shoulder), using filtered portions of the solution under test, suitably diluted with Medium, if necessary, in comparison with the appropriate Working standard solution. Use Medium as the blank, and a 1.0-cm cell for Tablets labeled to contain 10 mg, 20 mg, or 40 mg; and a 0.5-cm cell for Tablets labeled to contain 80 mg. For Tablets labeled to contain 10 mg, 20 mg, or 40 mg, calculate the amount of oxycodone (C18H21NO4) dissolved by formula (1), in which C is the concentration, in mg per mL, of the appropriate Working standard solution; AU and AS are the absorbances of the solution under test and of the appropriate Working standard solution, respectively; V is the initial volume, in mL, of Medium in the vessel; VS is the volume, in mL, withdrawn from the vessel for previous samplings; C1 is the concentration, in mg per mL, of oxycodone in the Medium determined at 1 hour; C2 is the concentration, in mg per mL, of oxycodone in the Medium determined at 2 hours; C4 is the concentration, in mg per mL, of oxycodone in the Medium determined at 4 hours; C6 is the concentration, in mg per mL, of oxycodone in the Medium determined at 6 hours; C8 is the concentration, in mg per mL, of oxycodone in the Medium determined at 8 hours; 100 is the conversion factor to percentage; and L is the Tablet label claim, in mg.

Tolerances— The percentages of the labeled amount of oxycodone (C18H21NO4) dissolved at the times specified conform to Acceptance Table 2.

Medium: simulated gastric fluid (without enzymes); 900 mL.

Apparatus 1: 100 rpm.

Times: 1, 4, and 12 hours.

0.85% Phosphoric acid— Dilute 10 mL of phosphoric acid with water to 1 L.

Standard stock solution— Prepare a solution of USP Oxycodone RS in 0.85% Phosphoric acid containing about 0.9 mg per mL.

Working standard solution— Dilute the Standard stock solution, quantitatively and stepwise, with Medium to obtain a solution having a concentration of about 40% of the Tablet label claim. [note—This solution is stable for two weeks at room temperature.]

Test solution— Pass the solution under test through a suitable 0.45-µm filter.

Mobile phase— Weigh 23.1 g of monobasic potassium phosphate into a 4-L flask, and dissolve with 3400 mL of water. Add 4 mL of triethylamine, and adjust with 0.85% Phosphoric acid to a pH of 3.0 ± 0.1. Add 600 mL of methanol and 20 mL of tert-butyl methyl ether, and mix well. Filter and degas. Make adjustments if necessary (see System Suitability under Chromatography 621).

Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 230-nm detector and a 3.9-mm × 30-cm column that contains 10-µm packing L1 and that is maintained at a temperature of 60. The flow rate is about 1.0 mL per minute. Chromatograph the Working standard solution, and record the peak responses as directed for Procedure: the tailing factor is not more than 1.5 and not less than 0.75; the capacity factor is not less than 0.5; and the relative standard deviation for replicate injections is not more than 2%.

Procedure— Separately inject equal volumes (about 50 µL) of the Working standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the peak reponses. Calculate the amount of oxycodone (C18H21NO4) dissolved by formula (3), in which C is the concentration, in mg per mL, of the appropriate Working standard solution; rU and rS are the peak responses of the solution under test and of the appropriate Working standard solution, respectively; V is the initial volume, in mL, of Medium in the vessel under test; VS is the volume, in mL, withdrawn from the vessel for previous samplings; C1 is the concentration, in mg per mL, of oxycodone in the Medium determined at 1 hour; C4 is the concentration, in mg per mL, of oxycodone in the Medium determined at 4 hours; C12 is the concentration, in mg per mL, of oxycodone in the Medium determined at 12 hours; 100 is the conversion factor to percentage; and L is the Tablet label claim, in mg.

Tolerances— The percentages of the labeled amount of oxycodone (C18H21NO4) dissolved at the times specified conform to Acceptance Table 2.

(351.82/315.37)CD(rU / rS)