Physostigmine Sulfate
(C15H21N3O2)2·H2SO4
648.77
Pyrrolo[2,3-b]indol-5-ol,1,2,3,3a,8,8a-hexahydro-1,3a,8-trimethyl-,methylcarbamate (ester),(3aS-cis)-,sulfate (2:1).
Physostigmine sulfate (2:1) [64-47-1].
»Physostigmine Sulfate contains not less than 97.0percent and not more than 102.0percent of (C15H21N3O2)2·H2SO4,calculated on the dried basis.
Packaging and storage—
Preserve in tight,light-resistant containers.
Identification—
B:
Asolution (1in 100)responds to the tests for Sulfate á191ñ.
Specific rotation á781Sñ:
between -116
and -120.
and -120.
Test solution:
10mg per mL,in water.
Loss on drying á731ñ—
Dry it at 105to constant weight:it loses not more than 1.0%of its weight.
to constant weight:it loses not more than 1.0%of its weight.
Residue on ignition á281ñ:
negligible,from 100mg.
Readily carbonizable substances—
It meets the requirements of the test for Readily carbonizable substancesunder Physostigmine.
Assay—
Dissolve about 200mg of Physostigmine Sulfate,accurately weighed,in 25mLof water.Render the solution alkaline by the addition of about 1g of sodium bicarbonate,and extract with one 25-mLand five 10-mLportions of chloroform,each time shaking vigorously for 1minute.Filter each extract through glass wool.Add 15mLof glacial acetic acid and 10mLof acetic acid anhydride to the combined chloroform extracts,and titrate with 0.02Nperchloric acid VS,determining the endpoint potentiometrically.Perform a blank determination,and make any necessary correction.Each mLof 0.02Nperchloric acid is equivalent to 6.488mg of (C15H21N3O2)2·H2SO4.
Auxiliary Information—
Staff Liaison:Salvador C.Salado,M.S.,Scientist and Latin American Liaison
Expert Committee:(PA3)Pharmaceutical Analysis 3
USP28–NF23Page 1556
Phone Number:1-301-816-8165