C15H21N3O2 275.35

Pyrrolo[2,3-b]indol-5-ol, 1,2,3,3a,8,8a-hexahydro-1,3a,8-trimethyl-, methylcarbamate (ester), (3aS-cis).
Physostigmine.
1,2,3,3a,8,8a-Hexahydro-1,3a,8-trimethylpyrrolo[2,3-b]indol-5-yl methylcarbamate [57-47-6].

Packaging and storage— Preserve in tight, light-resistant containers.

USP Reference standards 11— USP Physostigmine Salicylate RS.

Identification— It meets the requirements of the test for Identification—Organic Nitrogenous Bases 181, USP Physostigmine Salicylate RS being used, and 1 g of sodium bicarbonate being used in place of the 2 mL of 1 N sodium hydroxide specified.

Specific rotation 781S: between 236 and 246 (= 365 nm).

Loss on drying 731— Dry it over silica gel for 24 hours: it loses not more than 1.0% of its weight.

Residue on ignition 281: negligible, from 100 mg.

Readily carbonizable substances 271— Dissolve 100 mg in 5 mL of sulfuric acid TS: at the end of 5 minutes the solution has no more color than Matching Fluid I.

Residual solvents 467: meets the requirements.

Assay— Dissolve about 175 mg of Physostigmine, accurately weighed, in 25 mL of chloroform. Add 25 mL of glacial acetic acid, and titrate with 0.02 N perchloric acid in dioxane VS, determining the endpoint potentiometrically. Perform a blank determination, and make any necessary correction. Each mL of 0.02 N perchloric acid is equivalent to 5.507 mg of C15H21N3O2.

Expert Committee : (MDPP05) Monograph Development-Psychiatrics and Psychoactives

USP29–NF24 Page 1728

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