Diphenhydramine Citrate
(dye'' fen hye' dra meen sit' rate).
C17H21NO·C6H8O7
447.48
447.48Ethanamine, 2-(diphenylmethoxy)-N,N-dimethyl-, 2-hydroxy-1,2,3-propanetricarboxylate (1:1).
2-(Diphenylmethoxy)-N,N-dimethylethylamine citrate (1:1)
[88637-37-0].»
Diphenhydramine Citrate contains not less than 98.0 percent and not more than 100.5 percent of C17H21NO·C6H8O7, calculated on the dried basis.
Diphenhydramine Citrate contains not less than 98.0 percent and not more than 100.5 percent of C17H21NO·C6H8O7, calculated on the dried basis.
Packaging and storage—
Preserve in tight, light-resistant containers.
USP Reference standards 
11
—
11—
USP Diphenhydramine Citrate RS 
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Melting range 741:
between 146
and 150, but the range between beginning and end of melting does not exceed 2.
741:
between 146 and 150, but the range between beginning and end of melting does not exceed 2.
Loss on drying 731—
Dry it at 105 for 3 hours: it loses not more than 0.5% of its weight.
731—
Dry it at 105 for 3 hours: it loses not more than 0.5% of its weight.
Residue on ignition 281—
To about 8 g, accurately weighed, add 5 mL of sulfuric acid, and char. After the substance is thoroughly charred, add 4 mL of nitric acid and a few drops of sulfuric acid, heat gently until fumes are no longer evolved, and ignite at 800 ± 25 until the carbon is consumed. Place in a muffle furnace at 550 ± 50 for about 1 hour. Continue the ignition until constant weight is attained: not more than 0.1% remains.
281—
To about 8 g, accurately weighed, add 5 mL of sulfuric acid, and char. After the substance is thoroughly charred, add 4 mL of nitric acid and a few drops of sulfuric acid, heat gently until fumes are no longer evolved, and ignite at 800 ± 25 until the carbon is consumed. Place in a muffle furnace at 550 ± 50 for about 1 hour. Continue the ignition until constant weight is attained: not more than 0.1% remains.
Assay—
Dissolve about 1.6 g of Diphenhydramine Citrate, accurately weighed, in a mixture of 100 mL of glacial acetic acid and 20 mL of xylene. Add 20 mL of mercuric acetate TS, and titrate with 0.1 N perchloric acid VS, determining the endpoint potentiometrically. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 44.75 mg of C17H21NO·C6H8O7.
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Domenick Vicchio, Ph.D.
Senior Scientific Liaison 1-301-998-6828 |
(SM42010) Monographs - Small Molecules 4 |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 2931