Identification—
Place in a separator a volume of Oral Topical Solution, equivalent to about 300 mg of lidocaine hydrochloride, and extract with four 15-mL portions of chloroform, discarding the chloroform extracts. Add 2 mL of 2 N sodium hydroxide to the aqueous solution remaining in the separator, and extract with four 15-mL portions of chloroform. Combine the chloroform extracts, and evaporate with the aid of a current of warm air to dryness. Dissolve the crystals so obtained in solvent hexane, evaporate with the aid of warm air, and dry the residue in vacuum over silica gel for 24 hours: the residue so obtained responds to
Identification test
A under
Lidocaine.
Assay—
Mobile phase, Standard preparation, and Resolution preparation—
Prepare as directed in the Assay for lidocaine hydrochloride under Lidocaine and Epinephrine Injection.
Assay preparation—
Transfer an accurately measured volume of Oral Topical Solution, equivalent to about 100 mg of lidocaine hydrochloride, to a 50-mL volumetric flask, dilute with Mobile phase to volume, and mix.
Procedure—
Proceed as directed for
Procedure in the
Assay for lidocaine hydrochloride under
Lidocaine and Epinephrine Injection. Calculate the quantity, in mg, of lidocaine hydrochloride (C
14H
22N
2O·HCl) in each mL of the Oral Topical Solution taken by the formula:
(270.80 / 234.34)(50)(C / V)(rU / rS),
in which
V is the volume, in mL, of Oral Topical Solution taken; and the other terms are as defined therein.
791
:
between 5.0 and 7.0.