Ethosuximide Capsules

General Notices

Action and use

Antiepileptic.

Definition

Ethosuximide Capsules contain Ethosuximide.

The capsules comply with the requirements stated under Capsules and with the following requirements.

Content of ethosuximide, C7H11NO2

95.0 to 105.0% of the stated amount.

Identification

A. Heat a quantity of the contents of the capsules containing 0.1 g of Ethosuximide with 0.2 g of resorcinol and 0.1 mL of sulfuric acid at 140° for 5 minutes, add 5 mL of water, make alkaline with 5m sodium hydroxide and add 0.2 mL to a large volume of water. A bright green fluorescence is produced.
B. To a quantity of the contents of the capsules containing 0.5 g of Ethosuximide add 15 mL of a 40% w/v solution of sodium hydroxide. Boil under a reflux condenser for 30 minutes, cool, acidify with hydrochloric acid and extract with three 30 mL quantities of ether. Wash the combined extracts with 5 mL of water and evaporate to dryness. The melting point of the residue, after recrystallisation from toluene and petroleum spirit (boiling range, 40° to 60°), is about 102°, Appendix V A.

Assay

Weigh 20 capsules. Open the capsules carefully without loss of shell material, express as much of the contents as possible and reserve the expressed material. Wash the shells with ether, discard the washings, allow the shells to stand at room temperature until the ether has evaporated and weigh. The difference between the weights represents the weight of the total contents. Dissolve a quantity of the contents containing 0.2 g of Ethosuximide in 30 mL of dimethylformamide and carry out Method II for non-aqueous titration, Appendix VIII A, using magneson solution as indicator and 0.1m tetrabutylammonium hydroxide VS as titrant. Each mL of 0.1m tetrabutylammonium hydroxide VS is equivalent to 14.12 mg of C7H11NO2.