Metoprolol Tartrate Oral Solution
» Metoprolol Tartrate Oral Solution contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of metoprolol tartrate [(C15H25NO3)2·C4H6O6]. Prepare Metoprolol Tartrate Oral Solution 10 mg per mL as follows (see Pharmaceutical Compounding—Nonsterile Preparations 795. See also Metoprolol Tartrate Oral Suspension):
Metoprolol Tartrate powder 1 g
Vehicle for Oral Solution (regular or
sugar-free), NF, a sufficient quantity		  
to make 100 mL
Add Metoprolol Tartrate powder and about 20 mL of Vehicle to a mortar, and mix. Add the Vehicle in small portions almost to volume, and mix thoroughly after each addition. Transfer the contents of the mortar, stepwise and quantitatively, to a calibrated bottle. Add enough Vehicle to bring to final volume, and mix well.
Packaging and storage— Preserve in tight, light-resistant containers. Store at controlled room temperature or in a cold place.
Labeling— Label it to state that it is to be well shaken, and to state the beyond-use date.
USP Reference standards 11—
USP Metoprolol Tartrate RS Click to View Structure
pH 791: between 3.6 and 4.6.
Beyond-use date: 60 days after the day on which it was compounded.
Assay—
Mobile phase— Prepare a suitable filtered and degassed solution by dissolving 961 mg of 1-pentanesulfonic acid sodium salt, monohydrate, and 82 mg of anhydrous sodium acetate in a mixture of 550 mL of methanol, 470 mL of water, and 0.57 mL of glacial acetic acid. Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard preparation— Dissolve USP Metoprolol Tartrate RS in water to obtain a solution having a known concentration of 100 µg per mL.
Assay preparation— Agitate the container of Oral Solution for 30 minutes on a rotating mixer, remove a 5-mL sample, and store in a clear glass vial at –70 until analyzed. At the time of analysis, remove the sample from the freezer, allow it to reach room temperature, and mix on a vortex mixer for 30 seconds. Pipet 1.0 mL of the sample into a 100-mL volumetric flask, and dilute with Mobile phase to volume.
Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm × 25-cm analytical column that contains 5-µm packing L1. The flow rate is about 1.0 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the retention time for metoprolol tartrate is about 7.3 minutes; and the relative standard deviation for replicate injections is not more than 1.3%.
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 responses for the major peaks. Calculate the quantity, in mg, of metoprolol tartrate [(C15H25NO3)2·C4H6O6] in the volume of Oral Solution taken by the formula:
100(C / V)(rU / rS)
in which C is the concentration, in µg per mL, of USP Metoprolol Tartrate RS in the Standard preparation; V is the volume, in mL, of Oral Solution taken; and rU and rS are the peak responses 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 Jeanne H. Sun
Assistant Scientific Liaison
1-301-816-3361		 (CMP2010) Compounding
Reference Standards RS Technical Services
1-301-816-8129
rstech@usp.org
USP35–NF30 Page 3900
Pharmacopeial Forum: Volume No. 32(1) Page 121