Pentobarbital Tablets
Action and use
Barbiturate.
Definition
Pentobarbital Tablets contain Pentobarbital Sodium.
Content of pentobarbital sodium, C11H17N2NaO3
92.5 to 107.5% of the stated amount.
Identification
Tests
Isomer
Dissolve a quantity of the powdered tablets containing 0.3 g of Pentobarbital Sodium in 5 mL of a 5% w/v solution of anhydrous sodium carbonate, heating gently if necessary. Add 10 mL of a 3% w/v solution of 4-nitrobenzyl chloride in ethanol (96%) and heat under a reflux condenser for 30 minutes. Cool to 25°, filter and wash the precipitate with five 5 mL quantities of water. Heat the precipitate with 25 mL of ethanol (96%) in a small flask under a reflux condenser until dissolved (about 10 minutes). Filter the hot solution, cool to 25° and, if necessary, scratch the side of the flask with a glass rod to induce crystallisation. Filter, wash the precipitate with two 5 mL quantities of water and dry at 100° to 105° for 30 minutes. The melting point of the dried precipitate is 136° to 148°, Appendix V A, Method I.
Assay
Weigh and powder 20 tablets. Dissolve a quantity of the powder containing 0.3 g of Pentobarbital Sodium as completely as possible in 10 mL of a 2% w/v solution of sodium hydroxide, saturate with sodium chloride, acidify with hydrochloric acid and extract with successive 15 mL quantities of ether until complete extraction is effected. Wash the combined extracts with two 2 mL quantities of water and extract the combined washings with 10 mL of ether. Add the ether to the main ether layer, filter and wash the filter with ether. Evaporate the solvent and dry the residue to constant weight at 105°. Each g of residue is equivalent to 1.097 g of C11H17N2NaO3.