Rifampin Oral Suspension
»Rifampin Oral Suspension contains not less than 90.0percent and not more than 110.0percent of the labeled amount of rifampin (C43H58N4O12).Use Rifampin or the number of Rifampin Capsules that contain the designated amount of Rifampin,and prepare Rifampin Oral Suspension as follows (see Pharmaceutical Compounding—Nonsterile Preparations á795ñ):
Rifampin 1.20g
Syrup,a sufficient quantity to make 120mL
Transfer 1.20g of Rifampin,or the contents of Rifampin Capsules,into a mortar.[NOTE—If necessary,gently crush the Capsule contents with a pestle to produce a fine powder.]Add about 2mLof Syrup to the mortar,and triturate until a smooth paste is formed.Add about 10mLof Syrup,and triturate to form a suspension.Continue to add Syrup,until about 80mLhas been added.Transfer this suspension to a 120-mLprecalibrated light-resistant glass or plastic prescription bottle.Rinse the mortar and pestle with successive small portions of Syrup,and add the rinses to the bottle.Shake vigorously.If necessary,add Citric Acid or Sodium Citrate to adjust to a pHof 5.0.Add a suitable flavor if desired.Add sufficient Syrup to make the product measure 120mL,and shake vigorously to produce the Oral Suspension.
Packaging and storage— Preserve in a tight,light-resistant glass or plastic prescription bottle,with a child-resistant closure.Store at controlled room temperature.
Labeling— Label it to state that the Suspension is to be well shaken.Label it to state that it contains 50mg of rifampin in 5mLof Oral Suspension.
pHá791ñ: between 4.5and 5.5.
Beyond-use date— Thirty days after the day on which it was compounded.
Assay—
Phosphate buffer,Solvent mixture,and Resolution solution— Prepare as directed in theAssay underRifampin.
Mobile phase— Prepare a suitable mixture of water,acetonitrile,Phosphate buffer,1.0Mcitric acid,and 0.5Msodium perchlorate (500:360:100:20:20),pass through a suitable filter having a 0.7-µm or finer porosity,and degas.Make adjustments if necessary (seeSystem SuitabilityunderChromatography á621ñ).
Diluent— Prepare a mixture of acetonitrile and water (1:1).
Standard preparation— Dissolve an accurately weighed quantity of USP Rifampin RSinDiluent to obtain a solution having a known concentration of about 0.5mg per mL,sonicating for about 30seconds,if necessary,to dissolve.Transfer 5.0mLof this solution to a 50-mL,low-actinic volumetric flask,dilute withDiluent to volume,and mix.[NOTE—Use this preparation within 1hour.]
Assay preparation— Transfer 5.0mLof Oral Suspension,freshly mixed and free from air bubbles,to a 100-mL,low-actinic volumetric flask,dissolve in and dilute withDiluent to volume,and mix.Transfer 5.0mLof the resulting solution to a 50-mL,low-actinic volumetric flask,dilute withDiluent to volume,and mix.
Chromatographic system(see Chromatography á621ñ)— The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm ×10-cm column that contains 5-µm packing L7.Chromatograph theResolution solution,and record the peak responses as directed forProcedure:the relative retention times are about 0.6for rifampin quinone and 1.0for rifampin;and the resolution,R,between the rifampin quinone and rifampin is not less than 4.0.Chromatograph theStandard preparation,and record the peak responses as directed forProcedure:the relative standard deviation for replicate injections is not more than 1.0%.
Procedure— Separately inject equal volumes (about 20µL)of theStandard preparation and theAssay preparation into the chromatograph,record the chromatograms,and measure the areas for the major peaks.Calculate the quantity,in mg,of rifampin (C43H58N4O12)in the portion of Oral Suspension taken by the formula:
1000C(rU/rS),
in whichCis the concentration,in mg per mL,of USP Rifampin RS,calculated on the dried basis,in theStandard preparation;andrUandrSare the rifampin peak responses obtained from theAssay preparation and theStandard preparation,respectively.
Auxiliary Information— Staff Liaison:Claudia C.Okeke,Ph.D.,Associate Director
Expert Committee:(CRX)Compounding Pharmacy
USP28–NF23Page 1729
Pharmacopeial Forum:Volume No.28(2)Page 363
Phone Number:1-301-816-8243