A: Finely powder 1Tablet,and transfer about half of the powder to a test tube.Add 1mLof 1Nsodium hydroxide and 10mLof water,and centrifuge.Add 5or 6drops of ferric chloride TS:a deep blue color develops,and almost immediately a gray-black precipitate forms(presence of acetaminophen).

B: The retention times of the hydrocodone bitartrate peak and the acetaminophen peak in the chromatogram of theAssay preparation correspond to those in the chromatogram of theStandard preparation,as obtained in theAssay.

TEST1: If the product complies with this test,the labeling indicates that it meets USPDissolution Test 1.

Medium: pH5.8±0.05phosphate buffer (seeBuffer Solutions in the section Reagents,Indicators,and Solutions);900mL.

Apparatus 2: 50rpm.

Time: 30minutes.

Procedure— Proceed as directed in theAssay,making any necessary modifications.

Tolerances— Not less than 80%(Q)each of the labeled amounts of acetaminophen (C8H9NO2)and hydrocodone bitartrate (C18H21NO3·C4H6O6·2½H2O)are dissolved in 30minutes.

TEST2: If the product complies with this test,the labeling indicates that it meets USPDissolution Test 2.

Medium: 0.1Nhydrochloric acid;900mL.

Apparatus,Time,and Procedure— Proceed as directed underTest 1.

Tolerances— Not less than 80%(Q)each of the labeled amounts of acetaminophen (C8H9NO2)and hydrocodone bitartrate (C18H21NO3·C4H6O6·2½H2O)is dissolved in 30minutes.

Buffer solution— Dissolve 6.8g of monobasic potassium phosphate in 1000mLof water.

Mobile phase— Prepare a filtered and degassed mixture ofBuffer solution and acetonitrile (85:15),and add 0.2mLof triethylamine per liter ofMobile phase.Make adjustments if necessary (seeSystem Suitability underChromatography á621ñ).

Hydrocodone bitartrate standard stock preparation— Dissolve an accurately weighed quantity of USP Hydrocodone Bitartrate RSinMobile phase,and dilute quantitatively,and stepwise if necessary,withMobile phase to obtain a solution having a known concentration of about 35µg per mL.

Standard preparation— Transfer about 38mg of USP Acetaminophen RS,accurately weighed,to a 50-mLvolumetric flask.Add an accurately measured volume ofHydrocodone bitartrate standard stock preparation containing about 38000Jµg of USP Hydrocodone Bitartrate RS,Jbeing the ratio of the labeled amount,in mg,of hydrocodone bitartrate to that of acetaminophen per Tablet,dilute withMobile phase to volume,and mix.This solution contains about 0.76mg of USP Acetaminophen RSper mLand about 760Jµg of USP Hydrocodone Bitartrate RSper mL.

Assay preparation— Weigh and finely powder not fewer than 20Tablets.Transfer an accurately weighed portion of the powder,equivalent to about 76mg of acetaminophen,to a 100-mLvolumetric flask,dissolve in and dilute withMobile phase to volume,and mix.Pass a portion of this mixture through a membrane having a 0.45-µm or finer porosity,discarding the first 5mLof the filtrate.

Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a detector set at 210nm for hydrocodone bitartrate and 295nm for acetaminophen and a 4.6-mm ×25-cm column that contains packing L1.The flow rate is about 1.5mLper minute.Chromatograph theStandard preparation,and record the peak responses as directed forProcedure:the relative retention times are about 1.0for acetaminophen and 2.0for hydrocodone;the resolution,R,between hydrocodone and acetaminophen is not less than 5.0;the tailing factor for the hydrocodone peak is not more than 1.6;and the relative standard deviation for replicate injections determined from both acetaminophen and hydrocodone is not more than 2.0%each.

Procedure— Separately inject equal volumes (about 20µL)of theStandard preparation and theAssay preparation into the chromatograph,record the chromatograms,and measure the responses for the major peaks.From the responses obtained at 210nm,calculate the quantity,in mg,of hydrocodone bitartrate (C18H21NO3·C4H6O6·2½H2O)in the portion of Tablets taken by the formula: in which 494.49is the molecular weight of hydrocodone bitartrate disesquihydrate;449.46is the molecular weight of anhydrous hydrocodone bitartrate;Cis the concentration,in µg per mL,of USP Hydrocodone Bitartrate RSin theStandard preparation;and rUand rSare the peak responses obtained from theAssay preparation and theStandard preparation,respectively.From the responses obtained at 295nm,calculate the quantity,in mg,of acetaminophen (C8H9NO2)in the portion of Tablets taken by the formula: in whichCis the concentration,in mg per mL,of USP Acetaminophen RSin theStandard preparation;andrUandrSare the peak responses obtained from theAssay preparation and theStandard preparation,respectively.