Prednisone
(pred' ni sone).
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C21H26O5 358.44 USP38

Pregna-1,4-diene-3,11,20-trione, USP38 17,21-dihydroxy-;    

17,21-Dihydroxypregna-1,4-diene-3,11,20-trione USP38     
[53-03-2].
DEFINITION
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PrednisoneUSP38 contains NLT 97.0% and NMT 102.0% of prednisone (C21H26O5), calculated on the anhydrous basis.
IDENTIFICATION
•  A. Infrared Absorption 197K
Analysis:  If a difference appears, dissolve portions of both the sample and the Reference Standard in methanol, evaporate the solutions to dryness, and repeat the tests.
Acceptance criteria:  Meets the requirements
•  B.
Analysis 1:  Dissolve 6 mg in 2 mL of sulfuric acid, and allow to stand for 5 min.
Acceptance criteria 1:  An orange color is produced.
Analysis 2:  Pour the resulting solution from Analysis 1 into 10 mL of water.
Acceptance criteria 2:  The color changes first to yellow and then, gradually, to bluish green.
ASSAY
•  Procedure
Mobile phase:  Peroxide-free tetrahydrofuran, methanol, and water (250:62:688)
Diluent:  Methanol and water (1:1)
Standard stock solution:  0.2 mg/mL of USP Prednisone RS in Diluent
Internal standard solution:  110 µg/mL of acetanilide in Diluent
Standard solution:  20 µg/mL of USP Prednisone RS and 11 µg/mL of acetanilide in Diluent from the Standard stock solution and the Internal standard solution, respectively. Prepare this solution fresh.
Sample stock solution:  0.2 mg/mL of Prednisone in Diluent
Sample solution:  20 µg/mL of Prednisone and 11 µg/mL of acetanilide in Diluent from the Sample stock solution and the Internal standard solution, respectively. Prepare this solution fresh.
Chromatographic system  
Mode:  LC
Detector:  UV 254 nm
Column:  4-mm × 25-cm; packing L1
Flow rate:  1.0 mL/min
Injection volume:  10 µL
System suitability 
Sample:  Standard solution
[Note—The retention times of acetanilide and prednisone are about 6 and 8 min, respectively. ]
Suitability requirements 
Resolution:  NLT 3 between prednisone and acetanilide
Relative standard deviation:  NMT 2.0%
Analysis 
Samples:  Standard solution and Sample solution
Calculate the percentage of prednisone (C21H26O5) in the portion of Prednisone taken:
Result = (RU/RS) × (CS/CU) × 100

RU== peak response ratio of prednisone to acetanilide from the Sample solution
RS== peak response ratio of prednisone to acetanilide from the Standard solution
CS== concentration of USP Prednisone RS in the Standard solution (µg/mL)
CU== concentration of Prednisone in the Sample solution (µg/mL)
Acceptance criteria:  97.0%–102.0% on the anhydrous basis
IMPURITIES
•  Residue on Ignition 281
Sample:  100 mg
Acceptance criteria:  Negligible
•  Organic Impurities
Mobile phase:  Chloroform and methanol (98:2)
Sample solution:  1.25 mg/mL of Prednisone in Mobile phase
Chromatographic system  
Mode:  LC
Detector:  UV 254 nm
Column:  6.0-mm × 4.0-cm; packing L3
Flow rate:  1 mL/min
Injection volume:  5 µL
System suitability 
Sample:  Sample solution
Suitability requirements 
Column efficiency:  NLT 2500 theoretical plates
Relative standard deviation:  NMT 2.0%
Analysis 
Sample:  Sample solution
Calculate the percentage of each impurity in the portion of Prednisone taken:
Result = (rU/rT) × 100

rU== peak response for each impurity
rT== sum of all the peak responses
Acceptance criteria 
Any individual impurity:  NMT 1.5%
Total impurities:  NMT 2.0%
SPECIFIC TESTS
•  Optical Rotation, Specific Rotation 781S
Sample solution:  5 mg/mL in dioxane
Acceptance criteria:  +167 to +175
Change to read:
•  Water Determination, Method I 921USP38
Acceptance criteria:  USP38 NMT 1.0% USP38
ADDITIONAL REQUIREMENTS
Change to read:
•  Packaging and Storage: Preserve in well-closed containers, protected from light and moisture. Store at controlled room temperature.USP38
Delete the following:
•   Labeling: Label to indicate whether it is hydrous or anhydrous.USP38
•  USP Reference Standards 11
USP Prednisone RS Click to View Structure
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Mary P. Koleck, Ph.D.
Scientific Liaison
(301) 230-7420
(SM42010) Monographs - Small Molecules 4
Reference Standards RS Technical Services
1-301-816-8129
rstech@usp.org
USP38–NF33 Page 4986
Pharmacopeial Forum: Volume No. 39(6)