Valganciclovir Hydrochloride
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C14H22N6O5·HCl 390.82

l-Valine, ester with 9-[[2-hydroxy-1-(hydroxymethyl)ethoxy]methyl]guanine, monohydrochloride.
l-Valine, 2-[(2-amino-1,6-dihydro-6-oxo-9H-purin-9-yl)methoxy]-3-hydroxypropyl ester, monohydrochloride [175865-59-5].
» Valganciclovir Hydrochloride contains not less than 97.0 percent and not more than 102.0 percent of C14H22N6O5·HCl, calculated on the anhydrous and solvent-free basis.
Packaging and storage— Preserve in tight containers. Store at 25, excursions permitted between 15 and 30.
Identification—
B: Ultraviolet Absorption 197U.
Solution: 10 µg per mL.
Medium: methanol.
C: A solution in water (1 in 20) meets the requirements of the tests for Chloride 191.
Water, Method I 921: not more than 8.0%, a 100-mg specimen being used.
Residue on ignition 281: not more than 0.10%, a 1-g specimen being used.
Limit of isopropyl alcohol—
Internal standard solution— Transfer 100 µL of 1,4-dioxane to a 100-mL volumetric flask, dilute with dimethylformamide to volume, and mix.
Standard stock solution— Transfer 1.0 mL of isopropyl alcohol and 0.1 mL of toluene to a 100-mL volumetric flask, dilute with dimethylformamide to volume, and mix. [note—Toluene is used to verify the system suitability.]
Standard solution— Transfer 2.0 mL of the Internal standard solution to a vial. Add 100 µL of Standard stock solution to the Internal standard solution, and mix.
System suitability solution— Use the Standard solution.
Test solution— Transfer between 90 mg to 100 mg of Valganciclovir Hydrochloride, accurately weighed, to a vial. Add 2.0 mL, accurately measured, of Internal standard solution, and mix.
Chromatographic system (see Chromatography 621)— The gas chromatograph is equipped with a flame-ionization detector and a 0.53-mm × 30-m capillary column coated with a 3.0-µm phase G43. The carrier gas is helium, flowing at a rate of about 10.5 mL per minute, and the split ratio is (1:15). The chromatograph is programmed as follows. Initially the column temperature is maintained at 40 for 10 minutes, and then the temperature is increased at a rate of 25 per minute to 240. [note—Condition the column at 240 after each injection for approximately 15 minutes.] The injection port temperature is maintained at about 250, and the detector temperature is maintained at about 300. Chromatograph the System suitability solution as directed for Procedure: the resolution, R, between 1,4-dioxane and toluene is not less than 8; the column efficiency, using the 1,4-dioxane peak, is not less than 6000 theoretical plates; and the relative standard deviation of the response area ratios of the isopropyl alcohol peak to the 1,4-dioxane peak for replicate injections is not more than 15%.
Procedure— Separately inject equal volumes (about 0.5 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the peak areas. Calculate the percentages of isopropyl alcohol in the portion of Valganciclovir Hydrochloride taken by the formula:
100(VC /W)(RU / RS)
in which V is the volume, in mL, of the Test solution; C is the concentration, in mg per mL, of isopropyl alcohol in the Standard solution; W is the weight, in mg, of Valganciclovir Hydrochloride taken; and RU and RS are the peak area ratios of isopropyl alcohol to the internal standard obtained from the Test solution and the Standard solution, respectively: not more than 1.0% of isopropyl alcohol is found.
Related compounds—
test 1
Solution A— Use 0.01 M Monobasic ammonium phosphate, prepare as directed in the Assay.
Solution B— Use methanol.
Mobile phase— Use variable mixtures of Solution A and Solution B as directed for Chromatographic system (see Table 1). Make adjustments if necessary (see System Suitability under Chromatography 621).
System suitability solution— Prepare as directed in the Assay.
Test solution— Use the Assay preparation.
Chromatographic system (see Chromatography 621) The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm × 15-cm column that contains packing L1. The chromatograph is programmed as shown in Table 1.
Table 1
Time
(minutes)
Solution A
(%)
Solution B
(%)
Elution
0–5 92 8 isocratic
5–15 92®80 8®20 linear gradient
15–30 80®30 20®70 linear gradient
[note—Equilibrate the column with starting Mobile phase for at least 15 minutes between injections.] The column temperature is maintained at 25, and the flow rate is about 1.0 mL per minute. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the resolution, R, between the first peak of valganciclovir and the methoxymethylguanine peak is not less than 1.0, and the resolution, R, between the two peaks for valganciclovir (R and S esters of l-valine) is not less than 3.0; the column efficiency determined using the second peak of valganciclovir is not less than 8000 theoretical plates; and the tailing factor for the second peak of valganciclovir is not more than 1.4. [note—The typical retention time for the second peak of valganciclovir is between 5 and 8.5 minutes.]
Procedure— Inject about 20 µL of the Test solution into the chromatograph, record the chromatogram, and measure the peak responses. The approximate relative retention times for each individual impurity are listed in Table 3. Calculate the percentage of each impurity in the portion of Valganciclovir Hydrochloride taken by the formula:
100(ri / Fi) /(Sri / Fi)
in which the ri is the area response for each impurity, and Fi is the relative response factor for each individual component listed in Table 3. The impurities meet the requirements as specified in Table 3.
test 2
Solution A— Dilute 2.5 mL of triethylamine with water to 1000 mL, and adjust with trifluoroacetic acid to a pH of 3.0 ± 0.05. Pass this solution through a filter having a 0.45-µm porosity, and degas. Make adjustments if necessary (see System Suitability under Chromatography 621).
Solution B— Use methanol.
Mobile phase— Use variable mixtures of Solution A and Solution B as directed for Chromatographic system (see Table 2). Make adjustments if necessary (see System Suitability under Chromatography 621).
System suitability solution— Prepare as directed in the Assay.
Test solution— Use the Assay preparation.
Chromatographic system (see Chromatography 621)—The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm ×15-cm column that contains packing L1. The chromatograph is programmed as follows in Table 2.
Table 2
Time
(minutes)
Solution A
(%)
Solution B
(%)
Elution
0–10 93 7 isocratic
10–20 93®70 7®30 linear gradient
[note—Equilibrate the column with starting Mobile phase for at least 15 minutes between injections.] The column temperature is maintained at 30, and the flow rate is about 1.0 mL per minute. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the resolution, R, between the two peaks for valganciclovir (R and S esters of l-valine) is not less than 1.3; the column efficiency determined using the second peak of valganciclovir is not less than 8000 theoretical plates; and the tailing factor for the second peak of valganciclovir is not more than 1.2. [note—The typical retention time for the second peak of valganciclovir is between 6 and 9 minutes.]
Procedure— Inject about 20 µL of the Test solution into the chromatograph, record the chromatogram, and measure the peak responses. Calculate the percentage of ganciclovir mono-N-methyl valinate impurity in the portion of Valganciclovir Hydrochloride taken by the formula:
100(ri / Fi)/S(ri / Fi)
in which ri is the sum of the area responses of ganciclovir mono-N-methyl valinate impurity (diastereomers); and Fi is the relative response factor for this impurity and valganciclovir as given in Table 3. The impurity limits meet the requirements specified in Table 3.
Table 3
Component Common Name Test
Number
Relative
Retention
Time
Relative
Response
Factor
Maximum
Limit
(%)
Valganciclovir Valganciclovir 1, 2 1.00 1.00
Aa Ganciclovir 1 0.42 1.4 1.5
Ba Guanine 1 0.28 1.9 0.25
Ca Methoxymethylguanine 1 0.81 1.0 0.3
Da, b Isovalganciclovir 1 1.26 1.0 0.5
Ea Monoacetoxyganciclovir 1 1.36 1.3 0.15
F (other identified
impurity)
Bis-valine easter of ganciclovir 1 1.61 0.71 0.1
Ga, b Homologue of valganciclovir 1 1.66 1.0 0.25
H 1 1.47 1.3 0.1
I 1 1.52 1.4 0.1
J (other identified
impurity)
Ganciclovir monopropionate 1 2.09 1.1 0.15
Ka Valganciclovir dimer
(stereoisomer A)
1 2.49 1.0 0.1
La Valganciclovir dimer
(stereoisomer B)
1 2.52 1.0 0.1
Ma Valganciclovir dimer
(stereoisomer C)
1 2.54 1.0 0.1
Na, b Ganciclovir mono-N-
methyl valinate
2 1.2 1.0 0.3
Other identified
impurity
1 1.0 0.1 individual; 0.25 total
Unidentified
impurity
1 and 2 1.0 0.1 individual; 0.25 total
Total of all
impurities
1 and 2 3.0
a  Specified impurity.
b  Reported as the sum of diastereomers.
Diastereomer ratio— Using the chromatogram for Test 1 in the test for Related compounds, calculate the percentage of valganciclovir (R and S esters of l-valine) by the following formulas:
100[rA (rA + rB)]
100[rB (rA + rB)]
in which rA and rB are the peak responses for valganciclovir (R and S esters of l-valine), respectively. The diastereomer ratio is (45:55) to (55:45).
Enantiomeric purity of valganciclovir—
Mobile phase— Dissolve 16.2 g of perchloric acid in 1000 mL of water, and mix. Pass this solution through a filter having a 0.5-µm or finer porosity, and degas. Make adjustments if necessary (see System Suitability under Chromatography 621).
System suitability solution— Transfer about 5 mg of USP Valganciclovir Hydrochloride RS and 0.5 mg of USP d-Valganciclovir RS to a 25-mL volumetric flask, dissolve in and dilute with 0.001 N hydrochloric acid to volume, and mix.
Test solution— Transfer about 10 mg of Valganciclovir Hydrochloride, accurately weighed, to a 50-mL volumetric flask, dissolve in and dilute with 0.001 N hydrochloric acid to volume, and mix.
Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 254-nm detector and a 4.0-mm×15-cm column that contains packing L66. The column temperature is maintained at ambient temperature, and the flow rate is about 0.8 mL per minute. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the resolution, R, between the second peak of the d-valine ester pair and the first peak of the valganciclovir pair is not less than 3.5; and the column efficiency determined using the second peak of valganciclovir is not less than 1800 theoretical plates.
Procedure— Inject about 20 µL of the Test solution into the chromatograph, record the chromatogram, and measure the peak responses. Calculate the enantiomeric purity, in percent, by the following formula:
100[rS / (rS + rIM)]
in which rS is the sum of the peak responses of valganciclovir (R and S esters of l-valine) and rIM is the sum of the peak responses of the enantiomeric impurities (R and S esters of d-valine), respectively. The enantiomeric purity is not less than 97.0%.
Assay—
0.10 M Monobasic ammonium phosphate solution— Dissolve 11.5 g of monobasic ammonium phosphate in about 900 mL of water, adjust with phosphoric acid (85%) to a pH of 2.8 ± 0.2, dilute with water to obtain 1000 mL of solution, and mix.
Mobile phase— Prepare a filtered and degassed mixture of 0.10 M Monobasic ammonium phosphate and methanol (92:8). Make adjustments if necessary (see System Suitability under Chromatography 621).
System suitability solution— Transfer about 10 mg of USP Valganciclovir Hydrochloride RS and 0.5 mg of USP Methoxymethylguanine RS to a 50-mL volumetric flask, dissolve in and dilute with 0.001 N hydrochloric acid to volume, and mix.
Standard preparation— Dissolve an accurately weighed quantity of USP Valganciclovir Hydrochloride RS in 0.001 N hydrochloric acid, and dilute quantitatively, and stepwise if necessary, to obtain a solution having a known concentration of about 0.2 mg per mL.
Assay preparation— Dissolve an accurately weighed quantity of Valganciclovir Hydrochloride in 0.001 N hydrochloric acid, and dilute quantitatively, and stepwise if necessary, to obtain a solution having a concentration of about 0.2 mg per mL.
Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm ×15-cm column that contains packing L1. The column temperature is maintained at 25, and the flow rate is about 1.0 mL per minute. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: meets the system suitability requirements as specified for Test 1 in the test for Related compounds. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the relative standard deviation of the correction factor (CF ) for replicate injections is not more than 1.0%. [note—CF is calculated as directed below in the Procedure.]
Procedure— Separately inject equal volumes (about 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the peak responses. Calculate the percentage, on the anhydrous and solvent-free basis, of C14H22N6O5·HCl in the portion of Valganciclovir Hydrochloride taken by the formula:
100[(rU / WU)(CF )(100) /(100 – SU)]
in which rU is the peak response (sum of two peaks for valganciclovir diastereomers) obtained from the Assay preparation; WU is the weight, in mg, of Valganciclovir Hydrochloride in the Assay preparation; CF is the correction factor; and SU is the total percent of solvent and water in the test sample.
The CF is calculated using the following formula:
(WS / RS)[(100 – SS) /100]
in which WS is the weight, in mg, of USP Valganciclovir Hydrochloride RS in the Standard preparation; RS is the area response (sum of two peaks for valganciclovir diastereomers) obtained from the Standard preparation; and SS is the total percent of solvent and water in USP Valganciclovir Hydrochloride RS.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Behnam Davani, Ph.D., M.B.A.
Senior Scientist
1-301-816-8394
(MDAA05) Monograph Development-Antivirals and Antimicrobials
Reference Standards Lili Wang, Technical Services Scientist
1-301-816-8129
RSTech@usp.org
USP32–NF27 Page 3834
Pharmacopeial Forum: Volume No. 33(1) Page 84
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.