Add the following:
Desonide
(des' oh nide).
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C24H32O6 416.51
Pregna-1,4-diene-3,20-dione, 11,21-dihydroxy-16,17-[(1-methylethylidene)bis(oxy)]-, (11,16)-;    
11,16,17,21-Tetrahydroxypregna-1,4-diene-3,20-dione cyclic 16,17-acetal with acetone     [638-94-8].
DEFINITION
Desonide contains NLT 98.0% and NMT 102.0% of the labeled amount of desonide (C24H32O6), calculated on the dried basis.
IDENTIFICATION
•  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
Use low-actinic glassware for all solutions containing desonide.
Solution A:  0.1% Phosphoric acid in water
Solution B:  Acetonitrile
Mobile phase:  See Table 1.
Table 1
Time
(min) 		Solution A
(%) 		Solution B
(%)
0 70 30
4 68 32
5 68 32
9 65 35
13 30 70
16 30 70
Diluent:  Solution A and acetonitrile (60:40)
System suitability solution:  0.7 mg/mL of USP Desonide Impurities Mixture RS in Diluent
Standard solution:  0.7 mg/mL of USP Desonide RS in Diluent
Sample solution:  0.7 mg/mL of Desonide in Diluent
Chromatographic system 
(See Chromatography 621, System Suitability.)
Mode:  LC
Detector:  UV 254 nm
Column:  4.6-mm × 15-cm; 2.6-µm packing L7
Temperatures 
Column:  20 (15–22 was shown to be acceptable)
Autosampler:  20
Flow rate:  1 mL/min
Injection volume:  5 µL
System suitability 
Samples:  System suitability solution and Standard solution
Suitability requirements 
Resolution:  NLT 2.0 between desonide glyoxal and deoxyprednisolone-16-ene; NLT 2.0 between desonide and dihydrodesonide, System suitability solution
Relative standard deviation:  NMT 0.73%, Standard solution
Analysis 
Samples:  Standard solution and Sample solution
Calculate the percentage of desonide (C24H32O6) in the portion of Desonide taken:
Result = (rU/rS) × (CS/CU) × 100

rU== peak response from the Sample solution
rS== peak response from the Standard solution
CS== concentration of USP Desonide RS in the Standard solution (mg/mL)
CU== concentration of Desonide in the Sample solution (mg/mL)
Acceptance criteria:  98.0%–102.0% on the dried basis
IMPURITIES
•  Residue on Ignition 281: NMT 0.10%
•  Organic Impurities
Solution A, Solution B, Mobile phase, Diluent, System suitability solution, Standard solution, Sample solution, and Chromatographic system:  Proceed as directed in the Assay.
Sensitivity solution:  0.28 µg/mL of USP Desonide RS in Diluent from the Standard solution
System suitability 
Samples:  System suitability solution and Sensitivity solution
Suitability requirements 
Resolution:  NLT 2.0 between desonide glyoxal and deoxyprednisolone-16-ene; NLT 2.0 between desonide and dihydrodesonide, System suitability solution
Signal-to-noise ratio:  NLT 10, Sensitivity solution
Analysis 
Sample:  Sample solution
Calculate the percentage of each impurity in the portion of Desonide taken:
Result = (rU/rT) × (1/F) × 100

rU== peak area of each impurity from the Sample solution
rT== total peak area from the Sample solution
F== relative response factor (see Table 2)
Acceptance criteria:  See Table 2.
[Note—Disregard peaks that are less than 0.04% of the desonide peak from the Standard solution. ]
Table 2
Name Relative
Retention
Time 		Relative
Response
Factor 		Acceptance
Criteria,
NMT (%)
16-Hydroxyprednisolonea 0.31 1.0 0.15
Prednisoloneb 0.48 1.0 0.15
Desonide glyoxalc 0.76 1.0 0.50
Deoxyprednisolone-16-ened 0.82 1.7 0.50
Sum of desonide glyoxal and deoxyprednisolone-16-ene — — 0.50
Desonide 1.00 — —
Dihydrodesonidee 1.07 0.84 0.50
Epoxydesonidef 1.18 1.0 0.50
Sum of dihydrodesonide and epoxydesonide — — 0.50
Bromodesonideg 1.43 0.68 0.15
Acetyldesonideh 1.74 0.82 0.15
Any other impurity — 1.0 0.10
Total impurities — — 1.0
a  11,16,17,21-Tetrahydroxy-3,20-dioxopregna-1,4-diene.
b  11,17,21-Trihydroxy-3,20-dioxopregna-1,4-diene.
c  11-Hydroxy-16,17-[(1-methylethylidene)bis(oxy)]-3,20-dioxopregna-1,4-dien-21-al.
d  11,21-Dihydroxypregna-1,4,16-triene-3,20-dione.
e  11,21-Dihydroxy-16,17-[(1-methylethylidene)bis(oxy)]pregn-4-ene-3,20-dione.
f  9,11-Epoxy-21-hydroxy-16,17-(1-methylethylidenedioxy)pregna-1,4-diene-3,20-dione.
g  9-Bromo-11,21-dihydroxy-16,17-[(1-methylethylidene)bis(oxy)]pregna-1,4-diene-3,20-dione.
h  11-Hydroxy-16,17-[(1-methylethylidene)bis(oxy)]-3,20-dioxopregna-1,4-dien-21-yl acetate.
SPECIFIC TESTS
•  Loss on Drying 731
Sample:  1.0 g
Analysis:  Dry at 105 for 3 h.
Acceptance criteria:  NMT 0.5%
•  Optical Rotation, Specific Rotation 781S
Sample:  10 mg/mL in dioxane
Acceptance criteria:  +104.0 to +110.0, calculated on the dried basis
ADDITIONAL REQUIREMENTS
•  Packaging and Storage: Preserve in tight containers, and store at controlled room temperature. Protect from light.
•  USP Reference Standards 11
USP Desonide RS
USP Desonide Impurities Mixture RS
This is a mixture that contains desonide and may contain about 1% each of 16-hydroxyprednisolone, prednisolone, desonide glyoxal, deoxyprednisolone-16-ene, dihydrodesonide, epoxydesonide, bromodesonide, and acetyldesonide.
USP38
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Domenick Vicchio, Ph.D.
Director - Chemical Medicines
(301) 998-6828		 (SM42010) Monographs - Small Molecules 4
Reference Standards RS Technical Services
1-301-816-8129
rstech@usp.org
USP38–NF33 Page 3024
Pharmacopeial Forum: Volume No. 39(5)