U.S. PHARMACOPEIA

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Thiopental Sodium for Injection
» Thiopental Sodium for Injection is a sterile mixture of Thiopental Sodium and anhydrous Sodium Carbonate as a buffer. It contains not less than 93.0 percent and not more than 107.0 percent of the labeled amount of C11H17N2NaO2S.
Packaging and storage— Preserve in Containers for Sterile Solids as described under Injections 1, preferably of Type III glass.
Completeness of solution 641— Mix 800 mg with 10 mL of carbon dioxide-free water: after 1 minute, the solution is clear and free from undissolved solid.
Constituted solution— At the time of use, it meets the requirements for Constituted Solutions under Injections 1.
Bacterial endotoxins 85— It contains not more than 1.0 USP Endotoxin Unit per mg of thiopental sodium.
pH 791: between 10.2 and 11.2, in the solution prepared in the test for Completeness of solution.
Residual solvents 467: meets the requirements.
(Official January 1, 2007)
Other requirements— It responds to the Identification tests and meets the requirements of the test for Heavy metals under Thiopental Sodium. It meets also the requirements for Sterility Tests 71, Uniformity of Dosage Units 905, and for Labeling under Injections 1.
Assay— Dissolve the contents of 10 containers of Thiopental Sodium for Injection in sufficient water, diluting to an accurately measured volume, to obtain a solution containing about 50 mg of thiopental sodium per mL. Dilute this solution quantitatively and stepwise with sodium hydroxide solution (1 in 250) to obtain a solution having a concentration of about 5 µg of thiopental sodium per mL. Proceed as directed in the Assay under Thiopental Sodium, beginning with “Dissolve an accurately weighed quantity of USP Thiopental RS.” Calculate the average quantity, in mg, of C11H17N2NaO2S in each container of Thiopental Sodium for Injection taken by the formula:
VC(1.091AU / AS),
in which V is the volume, in mL, of the solution prepared to contain about 50 mg of thiopental sodium per mL, C is the concentration, in µg per mL, of USP Thiopental RS in the Standard solution, 1.091 is the ratio of the molecular weight of thiopental sodium to that of thiopental, and AU and AS are the absorbances of the solution of Thiopental Sodium for Injection and the Standard solution, respectively.
Auxiliary Information— Staff Liaison : Daniel K. Bempong, Ph.D., Scientist
Expert Committee : (MDPS05) Monograph Development-Pulmonary and Steroids
USP29–NF24 Page 2131
Phone Number : 1-301-816-8143