Dimenhydrinate Oral Solution
» Dimenhydrinate Oral Solution contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of dimenhydrinate (C17H21NO·C7H7ClN4O2).
Packaging and storage— Preserve in tight containers.
USP Reference standards 11
USP Dimenhydrinate RS Click to View Structure
Identification— The relative retention times of the major peaks for 8-chlorotheophylline and diphenhydramine in the chromatogram of the Assay preparation correspond to those in the chromatogram of the Standard preparation, as obtained in the Assay.
Content of 8-chlorotheophylline—
Ammonium bicarbonate solution, Diluent, Solution A, Solution B, Mobile phase, Internal standard solution, and Chromatographic system— Proceed as directed in the Assay under Dimenhydrinate Tablets.
Standard solution— Prepare as directed for Standard preparation in the Assay under Dimenhydrinate Tablets.
Test solution— Prepare as directed for Assay preparation in the Assay.
Procedure— Separately inject equal volumes (about 10 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the areas for the major peaks. Calculate the quantity, in mg per mL, of 8-chlorotheophylline (C7H7ClN4O2) in the portion of Oral Solution taken by the formula:
(214.61/469.96)(0.05W)(RU / RS)
in which 214.61 and 469.96 are the molecular weights of 8-chlorotheophylline and dimenhydrinate, respectively; W is the weight, in mg, of USP Dimenhydrinate RS in the Standard solution; and RU and RS are peak area ratios of 8-chlorotheophylline to the internal standard obtained from the Test solution and the Standard solution, respectively. An amount of 8-chlorotheophylline that is between 43.4% and 47.9% of the amount of dimenhydrinate obtained in the Assay is found.
Alcohol content 611: between 4.0% and 6.0% of C2H5OH.
Assay—
Ammonium bicarbonate solution, Diluent, Solution A, Solution B, Mobile phase, Internal standard solution, Standard preparation, and Chromatographic system— Proceed as directed in the Assay under Dimenhydrinate Tablets.
Assay preparation— Pipet 5.0 mL of Oral Solution into a suitable container, add 5.0 mL of Internal standard solution, and mix. Transfer about 1 mL of this solution to a suitable container, add about 5 mL of Diluent, and mix.
Procedure— Proceed as directed for Procedure in the Assay under Dimenhydrinate Tablets. Calculate the quantity, in mg per mL, of dimenhydrinate (C17H21NO·C7H7ClN4O2) in the portion of the Oral Solution taken by the formula:
0.05W(RU / RS)
in which W is the weight, in mg, of USP Dimenhydrinate RS in the Standard preparation; and RU and RS are the peak area ratios of diphenhydramine to the internal standard obtained from the Assay preparation and the Standard preparation, respectively.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Elena Gonikberg, Ph.D.
Principal Scientific Liaison
1-301-816-8251
(SM32010) Monographs - Small Molecules 3
Reference Standards RS Technical Services
1-301-816-8129
rstech@usp.org
USP35–NF30 Page 2923
Pharmacopeial Forum: Volume No. 30(4) Page 1190