Butabarbital Sodium Elixir
(Current title—not to change until June 1,2005)
Monograph title change—to become official June 1,2005
See Butabarbital Sodium Oral Solution
»Butabarbital Sodium Elixir contains not less than 90.0percent and not more than 110.0percent of the labeled amount of C10H15N2NaO3.
Packaging and storage—
Preserve in tight containers.
Identification,Infrared Absorption á197Kñ—
Prepare the test specimen as follows.Place a volume of Elixir,equivalent to about 150mg of butabarbital sodium,in a separator,render it distinctly alkaline by the addition of 1Nsodium hydroxide,and saturate it with sodium chloride.Extract the mixture with two 15-mLportions of ether,and discard the ether.Acidify the solution with hydrochloric acid,and render it just alkaline to litmus by adding small portions of sodium bicarbonate (carbonate-free).Extract the liberated acid barbiturate,using five 20-mLportions of chloroform.Wash the combined chloroform extracts with 10mLof water acidified with 1drop of hydrochloric acid,then extract the water with 10mLof chloroform,adding the latter to the main chloroform solution.Filter the chloroform solution through a pledget of cotton or other suitable filter,previously washed with chloroform,into a tared beaker,and finally wash the separator and the filter with three 5-mLportions of chloroform.Evaporate the combined chloroform solution and washings on a steam bath with the aid of a current of air to dryness,and dry the residue at 105
for 2hours.
for 2hours.
Assay—
Internal standard solution—
Dissolve an accurately weighed quantity of secobarbital in chloroform,and quantitatively dilute with chloroform to obtain a solution having a known concentration of about 0.7mg per mL.
Standard preparation—
Dissolve accurately weighed quantities of USP Butabarbital RSand secobarbital in chloroform,and quantitatively dilute with chloroform to obtain a solution that contains,in each mL,known amounts of about 1mg of USP Butabarbital RSand about 1.4mg of secobarbital.
Assay preparation—
[NOTE—This preparation includes a bromination step for elimination of parabens and a carbonate-chloroform extraction for elimination of benzoic acid.]Transfer an accurately measured volume of Elixir,equivalent to about 30mg of butabarbital sodium,to a separator,add 1mLof bromine water (prepared by dissolving 2.0mLof bromine and 10g of potassium bromide in 60mLof water),and swirl.Allow to stand for 5minutes,add 1mLof sodium metabisulfite solution (1in 10),and swirl.Add 300mg of sodium bicarbonate in small portions,with mixing,and extract with four 10-mLportions of chloroform.Filter the extracts through about 15g of anhydrous sodium sulfate that is supported on a funnel by a small pledget of glass wool.Collect the combined filtrates in a 50-mLvolumetric flask,wash the sodium sulfate with 5mLof chloroform,collecting the washing with the filtrate,dilute with chloroform to volume,and mix.Combine 2.0mLof this solution with 2.0mLof Internal standard solutionin a suitable container,and reduce the volume to about 1mLby evaporation,with the aid of a stream of dry nitrogen,at room temperature.
Chromatographic system andSystem suitability—
Proceed as directed for Chromatographic Systemand System Suitabilityunder Barbiturate Assay á361ñ,the resolution,R,between butabarbital and secobarbital being not less than 2.4.[NOTE—Relative retention times are approximately 0.6for butabarbital and 1.0for secobarbital.]
Procedure—
Proceed as directed for Procedureunder Barbiturate Assay á361ñ.Calculate the quantity,in mg,of C10H15N2NaO3in each mLof the Elixir taken by the formula:
(234.23/212.25)(50)(RU)(QS)(Ci)/V(RS),
in which 234.23and 212.25are the molecular weights of butabarbital sodium and butabarbital,respectively;Vis the volume,in mL,of Elixir taken;and the other terms are as defined therein.
Auxiliary Information—
Staff Liaison:Ravi Ravichandran,Ph.D.,Senior Scientist
Expert Committee:(PA3)Pharmaceutical Analysis 3
USP28–NF23Page 302
Pharmacopeial Forum:Volume No.28(2)Page 259
Phone Number:1-301-816-8330