Primidone
218.254,6(1H,5H)-Pyrimidinedione, 5-ethyldihydro-5-phenyl-.
5-Ethyldihydro-5-phenyl-4,6(1H,5H)-pyrimidinedione
[125-33-7].» Primidone contains not less than 98.0 percent and not more than 102.0 percent of C12H14N2O2, calculated on the dried basis.
Packaging and storage—
Preserve in well-closed containers.
USP Reference standards 
11
—
USP Primidone RS.
11—
USP Primidone RS.
Identification—
A:
Infrared Absorption 197K—If a difference appears, dissolve portions of both the tests specimen and the Reference Standard in alcohol, evaporate the solutions to dryness, and repeat the tests.
197K—If a difference appears, dissolve portions of both the tests specimen and the Reference Standard in alcohol, evaporate the solutions to dryness, and repeat the tests.
B:
Ultraviolet Absorption 197U—
197U—
Solution:
400 µg per mL.
Medium:
alcohol.
Absorptivities at 257 nm, calculated on the dried basis, do not differ by more than 3.0%.
C:
Fuse 0.20 g with 0.20 g of anhydrous sodium carbonate: ammonia is evolved.
Loss on drying 731—
Dry it at 105
for 2 hours: it loses not more than 0.5% of its weight.
731—
Dry it at 105 for 2 hours: it loses not more than 0.5% of its weight.
Residue on ignition 281:
not more than 0.2%.
281:
not more than 0.2%.
Ordinary impurities 466—
466—
Test solution—
Prepare a solution in methanol having a known concentration of 2 mg per mL.
Standard solutions—
Prepare solutions in methanol having known concentrations of 2, 10, 20, and 40 µg per mL.
Eluant:
a mixture of butyl alcohol, glacial acetic acid, and water (5:3:2).
Visualization—
Expose the plate to chlorine gas for about 15 minutes, air-dry until the chlorine has dissipated (about 15 minutes), and follow with visualization technique 20.
Assay—
Transfer about 40 mg of Primidone, accurately weighed, to a 100-mL volumetric flask. Add 70 mL of alcohol, and boil gently to dissolve. Cool, and add alcohol to volume. Determine the absorbances in a 2-cm cell, with a suitable spectrophotometer, using alcohol as the blank, at the minima that occur at about 254 nm and 261 nm and at the maximum that occurs at about 257 nm. Concomitantly determine the absorbances of a Standard solution in alcohol of USP Primidone RS, similarly prepared to have a known concentration of about 400 µg per mL. Calculate the quantity, in mg, of C12H14N2O2 in the Primidone taken by the formula:
0.1C(2A257 – A254 – A261)U / (2A257 – A254 – A261)S
in which C is the concentration, in µg per mL, of USP Primidone RS in the Standard solution, and the parenthetic expressions are the differences in the absorbances of the two solutions at the wavelengths indicated by the subscripts for the solution of Primidone (U) and the Standard solution (S), respectively.
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
Chromatographic Column—
| Topic/Question | Contact | Expert Committee |
| Monograph | Ravi Ravichandran, Ph.D.
Senior Scientist 1-301-816-8330 |
(MDPP05) Monograph Development-Psychiatrics and Psychoactives |
| Reference Standards | Lili Wang, Technical Services Scientist 1-301-816-8129 RSTech@usp.org |
USP32–NF27 Page 3382
Pharmacopeial Forum: Volume No. 27(4) Page 2774
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.