Physostigmine
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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.
1,2,3,3ab,8,8ab-Hexahydro-1,3a,8-trimethylpyrrolo[2,3-b]indol-5-yl methylcarbamate [57-47-6].
»Physostigmine is an alkaloid usually obtained from the dried ripe seed of Physostigma venenosumBalfour (Fam.Leguminosae).It contains not less than 97.0percent and not more than 102.0percent of C15H21N3O2,calculated on the dried basis.
Packaging and storage— Preserve in tight,light-resistant containers.
Identification— It meets the requirements of the test for Identification—Organic Nitrogenous Bases á181ñ,USP Physostigmine Salicylate RSbeing used,and 1g of sodium bicarbonate being used in place of the 2mLof 1Nsodium hydroxide specified.
Specific rotation á781Sñ: between -236and -246(l=365nm).
Test solution: 10mg per mL,in methanol.
Loss on drying á731ñ— Dry it over silica gel for 24hours:it loses not more than 1.0%of its weight.
Residue on ignition á281ñ: negligible,from 100mg.
Readily carbonizable substances á271ñ— Dissolve 100mg in 5mLof sulfuric acid TS:at the end of 5minutes the solution has no more color than Matching Fluid I.
Assay— Dissolve about 175mg of Physostigmine,accurately weighed,in 25mLof chloroform.Add 25mLof glacial acetic acid,and titrate with 0.02Nperchloric acid in dioxane VS,determining the endpoint potentiometrically.Perform a blank determination,and make any necessary correction.Each mLof 0.02Nperchloric acid is equivalent to 5.507mg of C15H21N3O2.
Auxiliary Information— Staff Liaison:Salvador C.Salado,M.S.,Scientist and Latin American Liaison
Expert Committee:(PA3)Pharmaceutical Analysis 3
USP28–NF23Page 1555
Phone Number:1-301-816-8165