Baclofen Oral Suspension
» Baclofen Oral Suspension contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of baclofen (C10H12ClNO2). Prepare Baclofen Oral Suspension 5 mg per mL as follows (see Pharmaceutical Compounding—Nonsterile Preparations 795):
Baclofen 500 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 Baclofen Tablets, place the Tablets in a suitable mortar and comminute the Tablets to a fine powder, or add Baclofen powder. Add about 5 mL of the Vehicle to wet the powder, and triturate the powder to form a fine paste. Add the Vehicle in small portions almost to volume, and mix thoroughly after each addition. Transfer, stepwise and quantitatively, the contents of the mortar to a calibrated bottle. Add sufficient Vehicle to bring to final volume, and mix well.
Packaging and storage— Preserve in tight, light-resistant containers. Store in a cold place.
Labeling— Label it to state that it is to be well shaken, and to state the beyond-use date.
pH 791: between 4.2 and 5.2.
Beyond-use date: 35 days after the day on which it was compounded.
Mobile phase— Prepare a suspension of 0.05 M monobasic sodium phosphate and acetonitrile (80:20), and adjust with phosphoric acid to a pH of 3.5. Filter and degas. Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard stock preparation— Dissolve an accurately weighed quantity of USP Baclofen RS in water to obtain a concentration of about 1.0 mg per mL.
Standard preparation— Dilute the Standard stock preparation with water to obtain a suspension having a known concentration of 5 µg per mL.
Assay preparation— Shake thoroughly by hand each bottle of Oral Suspension. Pipet 0.5 mL of Oral Suspension from each bottle to a 500-mL volumetric flask, dilute with water to volume to obtain a concentration of 5 µg per mL, and pass through a 0.22-µm polyvinylidenefluoride (PVDF) filter.
Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 220-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 is about 5.5 for baclofen; and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure— Separately inject equal volumes (about 15 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 baclofen (C10H12ClNO2) in the volume of Oral Suspension taken by the formula:
1000(C/V)(rU / rS)
in which C is the concentration, in µg per mL, of USP Baclofen 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.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Rick G. Schnatz
Manager, Compounding Pharmacy Expert Committee
(CRX05) Compounding Pharmacy05
Reference Standards Lili Wang, Technical Services Scientist
USP32–NF27 Page 1626
Pharmacopeial Forum: Volume No. 32(1) Page 51