Nitrofurantoin Tablets
DEFINITION
Nitrofurantoin Tablets contain NLT 90.0% and NMT 110.0% of the labeled amount of nitrofurantoin (C8H6N4O5).
IDENTIFICATION
• A. Infrared Absorption
Sample:
Add 10 mL of 6 N acetic acid to an amount equivalent to 100 mg of nitrofurantoin from powdered Tablets. Boil for a few min, and filter while hot. Cool to room temperature, collect the precipitate of nitrofurantoin, and dry at 105
for 1 h.
for 1 h.
Acceptance criteria:
The IR absorption spectrum of a mineral oil dispersion of the precipitate from the Sample exhibits maxima only at the same wavelengths as that of a similar preparation of USP Nitrofurantoin RS.
• B.
The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.
ASSAY
• Procedure
Buffer:
Dissolve 6.8 g of monobasic potassium phosphate in 500 mL of water. Add about 30 mL of 1.0 N sodium hydroxide sufficient to adjust to a pH of 7.0, and dilute with water to 1 L.
Mobile phase:
Acetonitrile and Buffer (12:88)
Internal standard solution:
1 mg/mL of acetanilide in water
Standard solution:
0.56 mg/mL of USP Nitrofurantoin RS prepared as follows. Dissolve 50 mg of USP Nitrofurantoin RS in 40.0 mL of dimethylformamide, and add 50.0 mL of Internal standard solution.
Sample solution:
Nominally 0.56 mg/mL of nitrofurantoin prepared as follows. Mix an amount equivalent to 50 mg of nitrofurantoin from powdered Tablets (NLT 20) with 40.0 mL of dimethylformamide, and shake mechanically for 15 min. Add 50.0 mL of Internal standard solution, mix, and cool to room temperature. Pass a portion of the solution through a nylon filter having a pore size of 0.45-µm, discarding the first few mL of the filtrate.
Chromatographic system
[Note—Adjust the operating parameters so that the retention time of the nitrofurantoin peak is about 8 min and the peak height is about half full-scale. ]
Mode:
LC
Detector:
UV 254 nm
Column:
3.9-mm × 30-cm; packing L1
Injection size:
5–10 µL
System suitability
Sample:
Standard solution
Suitability requirements
Resolution:
NLT 3.0 between acetanilide and nitrofurantoin
Relative standard deviation:
NMT 2.0% determined from the ratio of the peak responses
Analysis
Samples:
Standard solution and Sample solution
Calculate the percentage of the labeled amount of nitrofurantoin (C8H6N4O5) in the portion of powdered Tablets taken:
Result = (RU/RS) × (CS/CU) × 100
| RU | = | = internal standard ratio (peak response of nitrofurantoin/peak response of acetanilide) from the Sample solution |
| RS | = | = internal standard ratio (peak response of nitrofurantoin/peak response of acetanilide) from the Standard solution |
| CS | = | = concentration of USP Nitrofurantoin RS in the Standard solution (mg/mL) |
| CU | = | = nominal concentration of nitrofurantoin in the Sample solution (mg/mL) |
Acceptance criteria:
90.0%–110.0%
PERFORMANCE TESTS
• Dissolution 
711
711
Medium:
pH 7.2 phosphate buffer (see Reagents, Indicators, and Solutions—Buffer Solutions); 900 mL
Apparatus 1:
100 rpm
Times:
60 and 120 min
Standard stock solution:
0.1 mg/mL of USP Nitrofurantoin RS prepared as follows. Dissolve the required amount of USP Nitrofurantoin RS in 5% of the final volume of dimethylformamide. Dilute to final volume with Medium.
Standard solution:
10 µg/mL of USP Nitrofurantoin RS in Medium from Standard stock solution
Sample solution:
Pass a portion of the solution under test through a suitable filter. Dilute with Medium, if necessary.
Analysis
Samples:
Standard solution and Sample solution
Analytical wavelength:
375 nm
Blank:
Medium
Calculate the percentage of the labeled amount of nitrofurantoin (C8H6N4O5) dissolved:
Result = (AU/AS) × (CS/L) × V × 100
| AU | = | = absorbance from the Sample solution |
| AS | = | = absorbance from the Standard solution |
| CS | = | = concentration of the Standard solution (mg/mL) |
| L | = | = label claim (mg/Tablet) |
| V | = | = volume of Medium, 900 mL |
Tolerances:
NLT 25% (Q) of the labeled amount of nitrofurantoin (C8H6N4O5) is dissolved in 60 min, and NLT 85% (Q) of the labeled amount of nitrofurantoin (C8H6N4O5) is dissolved in 120 min.
• Uniformity of Dosage Units 905:
Meet the requirements
905:
Meet the requirements
IMPURITIES
• Limit of Nitrofurazone
Buffer:
Proceed as directed in the Assay.
Mobile phase:
Tetrahydrofuran and Buffer (10:90)
System suitability stock solution:
5.0 µg/mL each of USP Nitrofurazone RS and USP Nitrofurantoin RS in dimethylformamide
System suitability solution:
0.5 µg/mL each of USP Nitrofurazone RS and USP Nitrofurantoin RS in Mobile phase from System suitability stock solution
Standard stock solution:
5.0 µg/mL of USP Nitrofurazone RS in dimethylformamide.
Standard solution:
Transfer 2.0 mL of the Standard stock solution into a glass-stoppered flask, and add 20.0 mL of water.
Sample solution:
Transfer an equivalent to 100 mg of nitrofurantoin from powdered Tablets into a 25-mL, glass-stoppered flask. Add 2.0 mL of dimethylformamide, and shake for 5 min. Add 20.0 mL of water, mix, and allow to stand for 15 min. Pass a portion of the mixture through a nylon filter of 0.45-µm pore size.
Chromatographic system
[Note—Adjust the operating parameters so that the nitrofurazone peak has a retention time of about 10.5 min and its height is about 0.1 full-scale. ]
Mode:
LC
Detector:
UV 375 nm
Column:
3.9-mm × 30-cm; packing L1
Flow rate:
1.6 mL/min
Injection size:
60–100 µL
System suitability
Samples:
System suitability solution and Standard solution
Suitability requirements
Resolution:
NLT 4.0 between the nitrofurantoin and nitrofurazone peaks, System suitability solution
Relative standard deviation:
NMT 2.0%, Standard solution
Analysis
Samples:
Standard solution and Sample solution
Acceptance criteria:
The height of any peak from the Sample solution at a retention time corresponding to that of the main peak from the Standard solution is NMT the height of the main peak from the Standard solution (NMT 0.01%).
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in tight, light-resistant containers.
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Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Leonel M. Santos, Ph.D.
Senior Scientific Liaison 1-301-816-8168 |
(SM12010) Monographs - Small Molecules 1 |
| 711 |
Margareth R.C. Marques, Ph.D.
Senior Scientific Liaison 1-301-816-8106 |
(GCDF2010) General Chapters - Dosage Forms |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 4062
Pharmacopeial Forum: Volume No. 35(1) Page 92