Identification—
Place a number of Suppositories,equivalent to 5mg of oxymorphone hydrochloride,in a 125-mLseparator.Add 25mLof 0.1Nhydrochloric acid,and shake without heating until the specimen is dissolved.Wash the solution with five 25-mLportions of chloroform,shaking the separator gently to avoid forming emulsions,and discard the chloroform washings.Adjust with 6Nammonium hydroxide to a pHof about 9.5,using short-range pHindicator paper,and extract with three 25-mLportions of chloroform,filtering the extracts through chloroform-moistened glass wool into a 200-mLround-bottom flask.Evaporate the combined extracts to dryness,using a rotary evaporator.Add 25mLof 0.1Nhydrochloric acid,insert the stopper,and swirl to dissolve the residue:the UVabsorption spectrum of the solution so obtained exhibits maxima and minima at the same wavelengths as that of a similar solution of
USP Oxymorphone RS,concomitantly measured.
Assay—
Mobile phase—
0.05MSodium borate adjusted to a pHof about 9.1.
Internal standard solution—
Prepare a solution of procaine hydrochloride in 0.01Nhydrochloric acid having a concentration of about 3mg per mL.
Standard preparation—
Using an accurately weighed quantity of
USP Oxymorphone RS,prepare a solution in 0.01Nhydrochloric acid having a known concentration of about 4.5mg per mL,sonicating,if necessary,to effect solution.Transfer 10.0mLof this solution,10.0mLof the
Internal standard solution,and 5.0mLof 0.01Nhydrochloric acid to a 125-mLseparator.Extract with four 25-mLportions of chloroform,discarding the chloroform layer each time.Transfer the aqueous layer to a suitable flask,and bubble filtered air through the solution for 10minutes to remove final traces of chloroform.The concentration of
USP Oxymorphone RSin the
Standard preparationis about 1.8mg per mL.
Assay preparation—
Transfer a number of Suppositories,accurately counted and equivalent to about 50mg of oxymorphone hydrochloride,to a 125-mLseparator.Add 15.0mLof 0.01Nhydrochloric acid,10.0mLof Internal standard solution,and 25mLof chloroform.Shake until the suppositories dissolve.Discard the chloroform layer.Extract the aqueous layer with three 25-mLportions of chloroform,discarding the chloroform each time.Transfer the aqueous layer to a suitable flask and bubble filtered air through the solution for 10minutes to remove final traces of chloroform.
Chromatographic system
(see
Chromatography á621ñ)—The liquid chromatograph is equipped with a 254-nm detector and a 2.1-mm ×100-cm column that contains packing L12.The flow rate is about 1mLper minute.Chromatograph five replicate injections of the
Standard preparation,and record the peak responses as directed for
Procedure:the relative standard deviation is not more than 2.0%,and the resolution factor between oxymorphone hydrochloride and procaine hydrochloride is not less than 1.5.
Procedure—
Separately inject equal volumes (about 15µL)of the
Standard preparationand the
Assay preparationinto the chromatograph by means of a suitable microsyringe or sampling valve,record the chromatograms,and measure the responses for the major peaks.The retention times are about 5and 7.5minutes for oxymorphone hydrochloride and procaine hydrochloride,respectively.Calculate the quantity,in mg,of C
17H
19NO
4·HCl in each Suppository taken by the formula:
(337.80/301.34)(25C/N)(RU/RS),
in which 337.80and 301.34are the molecular weights of oxymorphone hydrochloride and oxymorphone,respectively;
Cis the concentration,in mg per mL,of
USP Oxymorphone RSin the
Standard preparation;Nis the number of Suppositories taken;and
RUand
RSare the ratios of the peak responses of oxymorphone hydrochloride and procaine hydrochloride obtained from the
Assay preparationand the
Standard preparation,respectively.