Clonazepam Oral Suspension
» Clonazepam Oral Suspension contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of clonazepam (C15H10ClN3O3). Prepare Clonazepam Oral Suspension 0.1 mg per mL as follows (see Pharmaceutical Compounding—Nonsterile Preparations 795):
Clonazepam 10 mg
Vehicle: a mixture of Vehicle for Oral Solution, (regular or sugar-free), NF and Vehicle for Oral Suspension, NF (1:1),  
a sufficient quantity to make 100 mL
If using Tablets, comminute the Tablets into a fine powder in a suitable mortar, or add Clonazepam powder to the mortar. Add approximately 10 mL of the Vehicle, and mix to a uniform paste. 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 before use, and to state the beyond-use date.
USP Reference standards 11
USP Clonazepam 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.
Mobile phase— Prepare a filtered and degassed solution of water, methanol, and acetonitrile (4:3:3). Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard stock preparation— Dissolve an accurately weighed quantity of USP Clonazepam RS in acetonitrile to obtain a concentration of about 0.5 mg per mL.
Standard preparation— Dilute the Standard stock preparation with acetonitrile to obtain a solution having a known concentration of 25 µg per mL.
Assay preparation— Agitate the container of Oral Suspension 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 with a vortex mixer for 30 seconds. Pipet 2.5 mL of the sample solution into a 10-mL volumetric flask, and dilute with acetonitrile to volume.
Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm × 10-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 of clonazepam is about 7 minutes; and the relative standard deviation for replicate injections is not more than 1.8%.
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 clonazepam (C15H10ClN3O3) in the volume of Oral Suspension taken by the formula:
4(C/V)(rU / rS)
in which C is the concentration, in mg per mL, of USP Clonazepam RS in the Standard preparation; V is the volume, in mL, of Oral Suspension taken; and rU and rS are the peak responses obtained from the Assay preparation and the Standard preparation, respectively.
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Topic/Question Contact Expert Committee
Monograph Jeanne H. Sun
Assistant Scientific Liaison
(CMP2010) Compounding
Reference Standards RS Technical Services
USP35–NF30 Page 2725
Pharmacopeial Forum: Volume No. 32(1) Page 73