Meprobamate Oral Suspension
» Meprobamate Oral Suspension contains not less than 95.0 percent and not more than 110.0 percent of the labeled amount of C9H18N2O4.
Packaging and storage— Preserve in tight containers.
Identification— Mix 2 mL of Oral Suspension with 2 mL of acetone and 2 mL of a 1 in 100 solution of furfural in glacial acetic acid, add 5 mL of hydrochloric acid, and shake: a purple color is produced, and, on standing, it changes to blue, then to blue-black, and finally to black-brown.
Uniformity of dosage units 905
for oral suspension packaged in single-unit containers: meets the requirements.
Deliverable volume 698
for oral suspension packaged in multiple-unit containers: meets the requirements.
Assay— Transfer an accurately measured volume of Oral Suspension, equivalent to about 400 mg of meprobamate, to a separator, and completely extract the meprobamate with 20-mL portions of chloroform, filtering the extracts through a pledget of cotton enclosed in glass wool that previously has been moistened with chloroform. Collect the filtrate in a conical flask, add several glass beads to the flask, and evaporate on a steam bath to dryness. To the residue add 20 mL of water, heat on a steam bath for several minutes, then add 40 mL of hydrochloric acid, and reflux for 90 minutes. Remove the condenser, and continue boiling until the volume is reduced to about 20 mL. Cool to room temperature, add 50 mL of water, and cool in an ice bath. Add 1 drop of methyl red TS, and, while cooling continuously, cautiously neutralize with sodium hydroxide solution (4 in 10) until the indicator begins to change color. Add hydrochloric acid, if necessary, to restore the pink color, then carefully neutralize with 0.1 N sodium hydroxide VS. Add 30 mL of neutral formaldehyde solution (18% w/w), and titrate with 0.1 N sodium hydroxide VS until the solution becomes yellow. Add 0.2 mL of phenolphthalein TS, and continue the titration with 0.1 N sodium hydroxide VS to a distinct pink color. Perform a blank determination, and make any necessary correction. Each mL of the total volume of 0.1 N sodium hydroxide consumed after the addition of the formaldehyde solution is equivalent to 10.91 mg of C9H18N2O4.
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Topic/Question Contact Expert Committee
Monograph Hariram Ramanathan, M.S.
Associate Scientific Liaison
(SM42010) Monographs - Small Molecules 4
USP35–NF30 Page 3808
Pharmacopeial Forum: Volume No. 29(6) Page 1924