Related compounds
0.3% Triethylamine phosphate buffer and Mobile phase
Prepare as described in the Assay.
Test solution
Use the Assay preparation.
Chromatographic system (see Chromatography
621
)
The liquid chromatograph is equipped with a 250-nm detector and a 4.6-mm × 15-cm column that contains packing L7. The flow rate is about 1.5 mL per minute. The column temperature is maintained at 45

. Chromatograph the
System suitability solution, and record the peak responses as directed for
Procedure: the resolution,
R, between mycophenolate mofetil related compound A and mycophenolate mofetil related compound B is not less than 1.5.
Procedure
Inject a volume (about 10 µL) of the
Test solution into the chromatograph, record the chromatogram, and measure the peak responses. Calculate the percentage of each impurity in the portion of Mycophenolate Mofetil taken by the formula:
100(rI / rs)
in which
rI is the peak response for each impurity; and
rs is the sum of the responses of all peaks.
Related Compound |
Relative Retention Time |
Limit (%) |
Mycophenolic acid1 |
about 0.33 |
0.5 |
Mycophenolate mofetil related compound A2 |
about 0.45 |
0.1 |
Mycophenolate mofetil related compound B3 |
about 0.49 |
0.1 |
N-Oxide analog4 |
about 0.60 |
0.1 |
1-Morphololinoethoxy analog5 |
about 0.86 |
0.1 |
O-Methyl analog6 |
about 1.2 |
0.1 |
Methyl mycophenolate7 |
about 1.5 |
0.1 |
Total specified impurities |
|
0.5 |
Individual unknown impurities |
|
0.1 |
Total unknown impurities |
|
0.1 |
Total impurities |
|
1.0 |
1
(E)-6-(1,3-dihydro-4-hydroxy-6-methoxy-7-methyl-3-oxo-5-isobenzofuranyl)-4-methyl-4-hexenoic acid.
|
2
2-Morpholinoethyl (E)-6-(1,3-dihydro-4,6-dihydroxy-7-methyl-3-oxo-5-isobenzofuranyl)-4-methyl-4-hexenoate.
|
3
(RS)-7-hydroxy-5-methoxy-4-methyl-6-[2-(5-methyl-2-oxo-tetrahydrofuran-5-yl)ethyl]-3H-isobenzofuranyl-1-one.
|
4
2-Morpholinoethyl (E)-6-(1,3-dihydro-4-hydroxy-6-methoxy-7-methyl-3-oxo-5-isobenzofuranyl)-4-methyl-4-hexenoate N-oxide.
|
5
2-Morpholinoethyl (RS)-(E)-6-(1,3-dihydro-4-hydroxy-6-methoxy-7-methyl-1-(2-morpholinoethoxy)-3-oxo-5-isobenzofuranyl)-4-methyl-4-hexenoate.
|
6
2-Morpholinoethyl (E)-6-(1,3-dihydro-4,6-dimethoxy-7-methyl-3-oxo-5-isobenzofuranyl)-4-methyl-4-hexenoate.
|
7
Methyl (E)-6-(1,3-dihydro-4-hydroxy-6-methoxy-7-methyl-3-oxo-5-isobenzofuranyl)-4-methyl-4-hexenoate.
|
Assay
0.3% Triethylamine phosphate buffer
Add 4 mL of triethylamine to 1300 mL of water. Adjust with phosphoric acid to a pH of 5.3.
Mobile phase
Prepare a suitable mixture of
0.3% Triethylamine phosphate buffer and acetonitrile (65:35). Make adjustments if necessary (see
System Suitability under
Chromatography
621
).
Standard preparation
Dissolve an accurately weighed quantity of
USP Mycophenolate Mofetil RS in acetonitrile, and dilute quantitatively, and stepwise if necessary, to obtain a solution having a known concentration of about 1.0 mg per mL.
Assay preparation
Transfer about 50 mg of mycophenolate mofetil, accurately weighed, to a 50-mL volumetric flask, dissolve in and dilute with acetonitrile to volume, and mix.
Chromatographic system (see Chromatography
621
)
The liquid chromatograph is equipped with a 250-nm detector and a 4.6-mm × 15-cm column that contains packing L7. The flow rate is about 1.5 mL per minute. The column temperature is maintained at 45

. Chromatograph the
Standard preparation, and record the peak responses as directed for
Procedure: the column efficiency is not less than 8000 theoretical plates; the tailing factor is not more than 1.5; and the relative standard deviation for replicate injections is not more than 1.0%.
Procedure
Separately inject equal volumes (about 10 µL) of the
Standard preparation and the
Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C
23H
31NO
7 in the portion of Mycophenolate Mofetil taken by the formula:
50C(rU / rS)
in which
C is the concentration, in mg per mL, of
USP Mycophenolate Mofetil RS in the
Standard preparation; and
rU and
rS are the peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.