Metronidazole Benzoate Compounded Oral Suspension
DEFINITION
Metronidazole Benzoate Compounded Oral Suspension contains NLT 90.0% and NMT 110.0% of the labeled amount of metronidazole (C6H9N3O3).
Prepare Metronidazole Benzoate Compounded Oral Suspension containing 50 mg/mL of metronidazole as follows (see Pharmaceutical Compounding—Nonsterile Preparations 
795
).
795). | Metronidazole (as the Benzoate) powder | 5 g (8 g) |
| Ora-Blenda, a sufficient quantity to make | 100 mL |
|
a
Perrigo, Minneapolis, MN.
|
|
Place the Metronidazole Benzoate powder into a suitable mortar. Wet the powder with a small amount of Ora-Blend, and triturate to make a smooth paste. Add the Ora-Blend in small portions almost to volume, and mix thoroughly after each addition. Transfer the contents of the mortar, stepwise and quantitatively, to a calibrated container. Add sufficient Ora-Blend to bring the preparation to final volume. Shake to mix well.
ASSAY
• Procedure
Solution A:
0.1% (v/v) glacial acetic acid in water
Mobile phase:
Acetonitrile and Solution A (40:60). Filter, and degas.
Standard solution:
0.4 mg/mL of metronidazole prepared from USP Metronidazole Benzoate RS in Mobile phase. Mix well until dissolved.
Sample solution:
Shake thoroughly each bottle of Oral Suspension. Transfer 0.8 mL of the Oral Suspension into a 100-mL volumetric flask, dilute with Mobile phase to volume, and mix well.
Chromatographic system
Mode:
LC
Detector:
UV 316 nm
Column:
4.6-mm × 15-cm; 5-µm packing L1
Column temperature:
30
Flow rate:
1.0 mL/min
Injection volume:
5 µL
System suitability
Sample:
Standard solution
[Note—The retention time for metronidazole is about 7.7 min. ]
Suitability requirements
Tailing factor:
NMT 2.0
Relative standard deviation:
NMT 2.0% for replicate injections
Analysis
Samples:
Standard solution and Sample solution
Calculate the percentage of the labeled amount of metronidazole (C6H9N3O3) in the portion of Oral Suspension taken:
Result = (rU/rS) × (CS/CU) × 100
| rU | = | = peak response from the Sample solution |
| rS | = | = peak response from the Standard solution |
| CS | = | = concentration of metronidazole in the Standard solution (mg/mL) |
| CU | = | = nominal concentration of metronidazole in the Sample solution (mg/mL) |
SPECIFIC TESTS
• pH 791:
3.6–4.6
791:
3.6–4.6
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Package in tight, light-resistant containers. Store at 2–8 or at controlled room temperature.
–8 or at controlled room temperature.
• Beyond-Use Date:
NMT 90 days after the date on which it was compounded when stored at 2–8 or controlled room temperature.
–8 or controlled room temperature.
• Labeling:
Label it to indicate that it is to be well-shaken before use, and to state the Beyond-Use Date.
• USP Reference Standards 11
11
USP Metronidazole Benzoate RS 
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Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Jeanne H. Sun, Pharm.D.
Associate Scientific Liaison (301) 230-3361 |
(CMP2010) Compounding |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP38–NF33 Page 4382
Pharmacopeial Forum: Volume No. 39(4)