Ondansetron Hydrochloride
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C18H19N3O·HCl·2H2O 365.86

4H-Carbazol-4-one, 1,2,3,9-tetrahydro-9-methyl-3-(2-methyl-1H-imidazol-1-yl)methyl-, monohydrochloride, (±)-, dihydrate.
(±)-2,3-Dihydro-9-methyl-3-(2-methylimidazol-1-yl)methylcarbazol-4(1H)-one monohydrochloride dihydrate [103639-04-9].
» Ondansetron Hydrochloride contains not less than 98.0 percent and not more than 102.0 percent of C18H19N3O·HCl, calculated on the anhydrous basis.
Packaging and storage— Preserve in tight, light-resistant containers. Store at 25, excursions permitted between 15 and 30.
Identification—
B: Dissolve 20 mg in 2 mL of water, add 1 mL of 2 M nitric acid, and filter: the filtrate responds to the test for Chloride 191.
Water, Method Ia 921: between 9.0% and 10.5%.
Residue on ignition 281: not more than 0.1%.
Limit of ondansetron related compound D—
Mobile phase— Prepare a filtered and degassed mixture of 0.02 M monobasic potassium phosphate (previously adjusted with 1 M sodium hydroxide to a pH of 5.4) and acetonitrile (80:20). Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard solution— Dissolve an accurately weighed quantity of USP Ondansetron Related Compound D RS in Mobile phase, and dilute quantitatively, and stepwise if necessary, with Mobile phase to obtain a solution having a known concentration of about 0.4 µg per mL.
System suitability solution— Dissolve suitable quantities of USP Ondansetron Related Compound D RS and USP Ondansetron Related Compound C RS in Mobile phase, and dilute quantitatively, and stepwise if necessary, with Mobile phase to obtain a solution having a concentration of about 0.6 µg per mL and 1 µg per mL, respectively.
Test solution— Transfer about 50 mg of Ondansetron Hydrochloride, accurately weighed, to a 100-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix.
Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 328-nm detector and a 4.6-mm × 25-cm column that contains packing L10. The flow rate is about 1.5 mL per minute. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the relative retention times are about 0.8 for ondansetron related compound C and 1.0 for ondansetron related compound D; and the resolution, R, between ondansetron related compound C and ondansetron related compound D is not less than 1.5. Chromatograph the Standard solution, and record the peak responses as directed for Procedure: the column efficiency determined from the analyte peak is not less than 400 theoretical plates; and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure— Separately inject equal volumes (about 20 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the percentage of ondansetron related compound D in the portion of Ondansetron Hydrochloride taken by the formula:
10,000(C/W)(rU / rS)
in which C is the concentration, in mg per mL, of USP Ondansetron Related Compound D RS in the Standard solution; W is the weight, in mg, of Ondansetron Hydrochloride taken to prepare the Test solution; and rU and rS are the peak areas obtained from the Test solution and the Standard solution, respectively: not more than 0.10% is found.
Chromatographic purity—
method i—
Resolution solution— Dissolve a quantity of USP Ondansetron Resolution Mixture RS in methanol, and dilute quantitatively, and stepwise if necessary, with methanol to obtain a solution having a known concentration of 12.5 mg per mL.
Standard solutions— Dissolve an accurately weighed quantity of USP Ondansetron Hydrochloride RS in methanol, and mix to obtain a solution having a known concentration of about 0.25 mg per mL. Quantitatively dilute this solution with methanol to obtain Standard solutions, designated below by letter, having the following compositions:
Standard
solution		 Dilution Concentration
(µg RS
per mL)		 Percentage
(%, for
comparison
with test
specimen)
A (1 in 5) 50 0.4
B (1 in 10) 25 0.2
C (1 in 20) 12.5 0.1
Test solution— Dissolve an accurately weighed quantity of Ondansetron Hydrochloride in methanol to obtain a solution containing 12.5 mg per mL.
Procedure— Separately apply 20 µL of the Test solution, 20 µL of each Standard solution, and 20 µL of the Resolution solution to a thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture. Develop the chromatogram in a solvent system consisting of a mixture of chloroform, ethyl acetate, methanol, and ammonium hydroxide (90:50:40:1) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the chamber, mark the solvent front, and allow the solvent to evaporate. Examine the plate under short-wavelength UV light: complete resolution of the three components of the Resolution solution spot is found. Compare the intensities of any secondary spots observed in the chromatogram of the Test solution with those of the principal spots in the chromatograms of the Standard solutions: any secondary spot from the chromatogram of the Test solution having an RF value corresponding to that of the uppermost secondary spot of the Resolution solution is not larger or more intense than the principal spot obtained from Standard solution A (0.4%); and no other secondary spot from the chromatogram of the Test solution is larger or more intense than the principal spot obtained from Standard solution B (0.2%).
method ii—
Mobile phase and Chromatographic system— Proceed as directed in the Assay.
Standard solution— Proceed as directed for Standard preparation in the Assay.
Test solution— Use the Assay preparation.
Procedure— Separately inject equal volumes (about 10 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the peak responses. Calculate the percentage of each impurity in the portion of Ondansetron Hydrochloride taken by the formula:
50,000(C/W)(1/F)(ri / rS)
in which C is the concentration, in mg per mL, of USP Ondansetron Hydrochloride RS in the Standard solution; W is the weight, in mg, of Ondansetron Hydrochloride taken to prepare the Test solution; F is the relative response factor of the impurities as described in the accompanying table; ri is the peak area for each impurity in the Test solution; and rS is the peak area of ondansetron obtained from the Standard solution: it meets the requirements given in the accompanying table.
Compound Name Relative Retention Time Relative
Response
Factor		 Limit (%)
Ondansetron related compound C about 0.32 1.2 0.2
Ondansetron related compound D* about 0.34 — 0.1
Imidazole about 0.49 0.3 0.2
2-methylimidazole about 0.54 0.4 0.2
Ondansetron 1.0 — —
Ondansetron related compound A about 1.10 0.8 0.2
Unknown — 1.0 0.1
Total — — 0.5
*  Quantified in the test for Limit of ondansetron related compound D.
Assay—
Mobile phase— Prepare a filtered and degassed mixture of 0.02 M monobasic sodium phosphate (previously adjusted with 1 M sodium hydroxide to a pH of 5.4) and acetonitrile (50:50). Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard preparation— Dissolve an accurately weighed quantity of USP Ondansetron Hydrochloride RS in Mobile phase, and dilute quantitatively, and stepwise if necessary, with Mobile phase to obtain a solution having a known concentration of about 90 µg per mL.
System suitability solution— Dissolve suitable quantities of USP Ondansetron Hydrochloride RS and USP Ondansetron Related Compound A RS in Mobile phase, and dilute quantitatively, and stepwise if necessary, with Mobile phase to obtain a solution containing about 90 µg per mL and 20 µg per mL, respectively.
Assay preparation— Transfer about 45 mg of Ondansetron Hydrochloride, accurately weighed, to a 50-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix. Pipet 5.0 mL of this solution into a 50-mL volumetric flask, dilute with Mobile phase to volume, and mix.
Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 216-nm detector and a 4.6-mm × 25-cm column that contains packing L10. The flow rate is about 1.5 mL per minute. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the relative retention times are about 1.0 for ondansetron and 1.1 for ondansetron related compound A; and the resolution, R, between ondansetron related compound A and ondansetron is not less than 1.5. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the tailing factor is not more than 2.0; and the relative standard deviation for replicate injections is not more than 1.5%.
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 C18H19N3O·HCl in the portion of Ondansetron Hydrochloride taken by the formula:
500C(rU / rS)
in which C is the concentration, in mg per mL, of USP Ondansetron Hydrochloride RS in the Standard preparation; and rU and rS are the peak areas obtained from the Assay preparation and the Standard preparation, respectively.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Ravi Ravichandran, Ph.D.
Senior Scientist
1-301-816-8330		 (MDPP05) Monograph Development-Psychiatrics and Psychoactives
Reference Standards Lili Wang, Technical Services Scientist
1-301-816-8129
RSTech@usp.org
USP32–NF27 Page 3138
Pharmacopeial Forum: Volume No. 32(1) Page 126
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.