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Tigecycline
(tye'' ge sye' kleen).
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C29H39N5O8 585.65
2-Naphthacenecarboxamide, 4,7-bis(dimethylamino)-9-[[[(1,1-dimethylethyl)amino]acetyl]amino]-1,4,4a,5,5a,6,11,12a-octahydro-3,10,12,12a-tetrahydroxy-1,11-dioxo-, (4S,4aS,5aR,12aS)-;    
(4S,4aS,5aR,12aS)-9-[2-(tert-Butylamino)acetamido]-4,7-bis(dimethylamino)-1,4,4a,5,5a,6,11,12a-octahydro-3,10,12,12a-tetrahydroxy-1,11-dioxo-2-naphthacenecarboxamide     [220620-09-7].
DEFINITION
Tigecycline contains NLT 97.0% and NMT 102.0% of tigecycline (C29H39N5O8), calculated on the anhydrous and solvent-free basis.
[Note—Handle Standards and samples under moisture-controlled conditions to prevent degradation in quantitative applications where degradation could impact results. ]
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
Protect solutions containing tigecycline from light using low-actinic glassware. Store these solutions at 10 immediately after preparation and during analysis.
Buffer:  4.35 g/L of dibasic potassium phosphate and 0.93 g/L of edetate disodium, adjusted with phosphoric acid to a pH of 6.2
Mobile phase:  Acetonitrile and Buffer (140:860)
Diluent:  4.35 g/L of dibasic potassium phosphate and 0.5 g/L of sodium bisulfite, adjusted with 1 N potassium hydroxide to a pH of 8.0
System suitability stock solution:  Dissolve 10 mg of USP Tigecycline RS in 10.0 mL of water. Add 1 or 2 drops of trifluoroacetic acid, heat at about 65 for 15 min, and cool.
System suitability solution:  Dilute 5.0 mL of the System suitability stock solution with water to 50.0 mL.
Standard solution:  0.1 mg/mL of USP Tigecycline RS in Diluent
Sample solution:  0.1 mg/mL of Tigecycline in Diluent
Chromatographic system 
(See Chromatography 621, System Suitability.)
Mode:  LC
Detector:  UV 248 nm
Column:  4.6-mm × 15-cm; 5-µm packing L1
Temperatures 
Column:  30
Autosampler:  10
Flow rate:  1 mL/min
Injection volume:  20 µL
System suitability 
Samples:  System suitability solution and Standard solution
[Note—The relative retention times for the tigecycline epimer and tigecycline are about 0.67 and 1.0, respectively. ]
Suitability requirements 
Resolution:  NLT 3.0 between the tigecycline epimer and tigecycline, System suitability solution
Tailing factor:  0.7–1.5, Standard solution
Relative standard deviation:  NMT 1.0%, Standard solution
Analysis 
Samples:  Standard solution and Sample solution
Calculate the percentage of the labeled amount of tigecycline (C29H39N5O8) in the portion of Tigecycline 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 Tigecycline RS in the Standard solution (mg/mL)
CU== concentration of Tigecycline in the Sample solution (mg/mL)
Acceptance criteria:  97.0%–102.0% on the anhydrous and solvent-free basis
IMPURITIES
•  Residue on Ignition 281: NMT 0.1%
•  Organic Impurities
Protect solutions containing tigecycline from light using low-actinic glassware. Store these solutions at 10 immediately after preparation and during analysis.
Solution A:  Dissolve 4.35 g of dibasic potassium phosphate and 0.93 g of edetate disodium in 950 mL of water. Adjust with phosphoric acid to a pH of 6.4 ± 0.05, and add 50 mL of acetonitrile.
Solution B:  Dissolve 4.35 g of dibasic potassium phosphate and 0.93 g of edetate disodium in 500 mL of water. Adjust with phosphoric acid to a pH of 6.4 ± 0.05, and add 500 mL of acetonitrile.
Mobile phase:  See Table 1.
Table 1
Time
(min) 		Solution A
(%) 		Solution B
(%)
0 85 15
40 57 43
55 0 100
58 0 100
59 85 15
66 85 15
Diluent:  4.35 g/L of dibasic potassium phosphate and 0.5 g/L of sodium bisulfite, adjusted with 1 N potassium hydroxide to a pH of 8.0
System suitability solution:  0.5 mg/mL of USP Tigecycline RS and 2.4 µg/mL of USP Tigecycline Related Compound B RS in Diluent
Standard solution:  0.005 mg/mL of USP Tigecycline RS in Diluent
Sensitivity solution:  0.25 µg/mL of USP Tigecycline RS in Diluent
Sample solution:  0.5 mg/mL of Tigecycline in Diluent
Chromatographic system 
(See Chromatography 621, System Suitability.)
Mode:  LC
Detector:  248 nm
Column:  4.6-mm × 15-cm; 3-µm packing L1
Temperatures 
Column:  30
Autosampler:  10
Flow rate:  1 mL/min
Injection volume:  25 µL
System suitability 
Samples:  System suitability solution, Standard solution, and Sensitivity solution
Suitability requirements 
Resolution:   NLT 1.5 between tigecycline related compound B and the tigecycline epimer, System suitability solution
Tailing factor:  0.7–1.5, Standard solution
Relative standard deviation:  NMT 5.0%, Standard solution
Signal-to-noise ratio:  NLT 10, Sensitivity solution
Analysis 
Samples:  Standard solution and Sample solution
Calculate the percentage of each impurity in the portion of Tigecycline taken:
Result = (rU/rS) × (CS/CU) × 100

rU== peak response of each impurity from the Sample solution
rS== peak response of tigecycline from the Standard solution
CS== concentration of USP Tigecycline RS in the Standard solution (mg/mL)
CU== concentration of Tigecycline in the Sample solution (mg/mL)
Acceptance criteria:  See Table 2. The reporting threshold is 0.05%.
Table 2
Name Relative
Retention
Time 		Acceptance
Criteria,
NMT (%)
Specified unidentified impurity 0.12 0.15
Specified unidentified impurity 0.23 0.15
Tigecycline open ringa,b 0.36 0.020
Specified unidentified impurity 0.50 0.15
Tigecycline 12-oxo-11-hydroxyc 0.55 0.15
Tigecycline related
compound Bd 		0.64 0.25
Tigecycline epimere 0.74 1.0
Specified unidentified impurity 0.76 0.15
Tigecycline 1.0 —
Tigecycline quinone
analogf 		1.3 0.15
Specified unidentified impurity 1.5 0.15
Minocycline 1.6 0.25
Tigecycline tricyclic
analogg 		1.7 0.15
Specified unidentified impurity 1.9 0.15
Any individual
unspecified impurity 		— 0.10
Total impurities — 2.2
a  To be reported if there is a peak with maximum absorbance at either 390 or 640 nm. The impurity is quantitated at 248 nm. The system may resolve two peaks. The limit is for the sum of the two peaks.
b  (3S,4R)-7-[2-(tert-Butylamino)acetamido]-3-[4-carbamoyl-2-(dimethylamino)-3,5,6-trihydroxybenzyl]-5-(dimethylimino)-1,4,8-trihydroxy-3,4,5,8-tetrahydronaphthalene-2-carboxylate.
c  (4S,4aS,12aS)-9-[2-(tert-Butylamino)acetamido]-4,7-bis(dimethylamino)- 3,10,11,12a-tetrahydroxy-1,12-dioxo-1,4,4a,5,12,12a-hexahydro-2-naphthacenecarboxamide.
d  (4S,4aS,5aR,12aS)-9-Amino-4,7-bis(dimethylamino)-3,10,12,12a-tetrahydroxy-1,11-dioxo-1,4,4a,5,5a,6,11,12a-octahydrotetracene-2-carboxamide hydrochloride.
e  (4R,4aS,5aR,12aS)-9-[2-(tert-Butylamino)acetamido]-4,7-bis(dimethylamino)-1,4,4a,5,5a,6,11,12a-octahydro-3,10,12,12a-tetrahydroxy-1,11-dioxo-2-naphthacenecarboxamide.
f  (S)-4-({6-[2-(tert-Butylamino)acetamido]-8-(dimethylamino)-5-hydroxy-4-oxo-1,2,3,4-tetrahydronaphthalen-2-yl}methyl)-2,5-dihydroxy-3,6-dioxocyclohexa-1,4-dienecarboxamide.
g  (1S,4aR,4bR,10aR,11aS)-7-[2-(tert-Butylamino)acetamido]-9-(dimethylamino)-1,4,4a,6-tetrahydroxy-2,5,12-trioxo-1,2,4a,5,10,10a,11,11a-octahydro-1,4b-methanobenzo[b]fluorene-3-carboxamide.
SPECIFIC TESTS
•  pH 791
Sample solution:  10 mg/mL
Acceptance criteria:  7.7–8.2
•  Water Determination, Method Ic 921
Sample solution:  50 mg/mL of Tigecycline in dimethyl sulfoxide
Acceptance criteria:  NMT 2.5%
•  Optical Rotation, Specific Rotation 781S
Sample solution:  1 mg/mL in water
Acceptance criteria:  240 to 215 on the anhydrous and solvent-free basis
•  Bacterial Endotoxins Test 85: Where the label states that Tigecycline is sterile or must be subjected to further processing during the preparation of injectable dosage forms, it contains NMT 1 USP Endotoxin Unit/mg of tigecycline.
ADDITIONAL REQUIREMENTS
•  Packaging and Storage: Preserve in air-tight, light-resistant containers under nitrogen, and store refrigerated.
•  Labeling: Where it is intended for use in preparing injectable dosage forms, the label states that it is sterile or must be subjected to further processing during the preparation of injectable dosage forms.
•  USP Reference Standards 11
USP Endotoxin RS
USP Tigecycline RS Click to View Structure
USP Tigecycline Related Compound B RS Click to View Structure
(4S,4aS,5aR,12aS)-9-Amino-4,7-bis(dimethylamino)-3,10,12,12a-tetrahydroxy-1,11-dioxo-1,4,4a,5,5a,6,11,12a-octahydrotetracene-2-carboxamide hydrochloride.
    C23H28N4O7·HCl         508.95
USP38
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USP38–NF33 Page 5576
Pharmacopeial Forum: Volume No. 39(6)