Primidone Oral Suspension
DEFINITION
Primidone Oral Suspension is a suspension of Primidone in a suitable aqueous vehicle. It contains, in each 100 mL, NLT 4.5 g and NMT 5.5 g of primidone (C12H14N2O2).
IDENTIFICATION
• A.
The retention time of the major peak in the Sample solution corresponds to that in the Standard solution, both relative to the internal standard, as obtained in the Assay.
ASSAY
• Procedure
Internal standard solution:
10 mg/mL of androsterone in alcohol
Standard solution:
1 mg/mL of USP Primidone RS in alcohol prepared as follows. Dissolve first in alcohol using 65% of the final volume, and boil for 1 h. Allow to cool to ambient temperature, and add the Internal standard solution to fill 10% of the final volume. Dilute with alcohol to volume, and filter.
Sample solution:
Nominally 1 mg/mL of primidone in alcohol, from well-mixed Oral Suspension prepared as follows. Dissolve first in alcohol using 70% of the final volume, and boil for 1 h. Allow to cool to ambient temperature, and add the Internal standard solution to fill 10% of the final volume. Dilute with alcohol to volume, and filter.
Chromatographic system
Mode:
GC
Detector:
Flame ionization
Column:
4.0-mm × 120-cm; packed with 10% liquid phase G3 on support S1AB
Temperature
Detector:
310
Injector:
310
Column:
260
Carrier gas:
Helium
Flow rate:
40 mL/min
Injection size:
3 µL
System suitability
Sample:
Standard solution (three replicate injections)
[Note—The relative retention times for primidone and androsterone are about 0.8 and 1.0, respectively. ]
Suitability requirements
Resolution:
NLT 1.5 between primidone and androsterone
Relative standard deviation:
NMT 2.0%
Analysis
Samples:
Standard solution and Sample solution
Calculate the quantity of primidone (C12H14N2O2), in mg, in each 100 mL of Oral Suspension taken:
Result = (RU/RS) × (CS/CU) × D × 100
| RU | = | = ratio of the peak response of primidone to the internal standard from the Sample solution |
| RS | = | = ratio of the peak response of primidone to the internal standard from the Standard solution |
| CS | = | = concentration of USP Primidone RS in the Standard solution (mg/mL) |
| CU | = | = nominal concentration of primidone in the Sample solution (mg/mL) |
| D | = | = density of the Oral Suspension (g/mL) |
Acceptance criteria:
4.5–5.5 g in each 100 mL
PERFORMANCE TESTS
• Uniformity of Dosage Units 
905
:
Meets the requirements for oral suspension packaged in single-unit containers
905:
Meets the requirements for oral suspension packaged in single-unit containers
• Deliverable Volume 698:
Meets the requirements for oral suspension packaged in multiple-unit containers
698:
Meets the requirements for oral suspension packaged in multiple-unit containers
SPECIFIC TESTS
• pH 791:
5.5–8.5
791:
5.5–8.5
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in tight, light-resistant containers.
• USP Reference Standards 11
11
USP Primidone RS 
') + '&img=../../images/v35300/cas-125-33-7.gif',600,500);)
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Hariram Ramanathan, M.S.
Associate Scientific Liaison 1-301-816-8313 |
(SM42010) Monographs - Small Molecules 4 |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 4415
Pharmacopeial Forum: Volume No. 29(6) Page 1970