Acetazolamide Oral Suspension
» Acetazolamide Oral Suspension contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of acetazolamide (C4H6N4O3S2). Prepare Acetazolamide Oral Suspension 25 mg per mL as follows (see Pharmaceutical Compounding—Nonsterile Preparations 795. See also Acetazolamide Oral Solution):
Acetazolamide 2.5 g
Vehicle: a mixture of Vehicle for Oral Solution, NF (regular or sugar-free), and Vehicle for Oral Suspension, NF (1:1), or Cherry Syrup, NF, a sufficient
quantity to make 100 mL
[Note—If Tablets are used instead of bulk powder, the preparation becomes a suspension and should be labeled as such.] If using Tablets place the Tablets in a mortar and comminute the Tablets to a fine powder, or add Acetazolamide powder. Add about 20 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 liquid 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.
pH 791: between 4.0 and 5.0 (Vehicle for Oral Solution and Vehicle for Oral Suspension), and between 3.1 and 3.9 (Cherry Syrup).
Beyond-use date: 60 days after the day on which it was compounded.
Mobile phase— Dissolve 4.1 g of anhydrous sodium acetate in 950 mL of water, add 20 mL of methanol and 30 mL of acetonitrile, and mix. Adjust with glacial acetic acid to a pH of 4.0. Filter and degas the solution. Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard stock preparation— Transfer about 25 mg of USP Acetazolamide RS, accurately weighed, to a 50-mL volumetric flask, add 5.0 mL of 0.5 N sodium hydroxide, and mix to dissolve. Dilute with water to volume, and mix.
Standard preparation— Transfer 25.0 mL of the Standard stock preparation to a 50-mL volumetric flask, and dilute with water to obtain a solution having a known concentration of 250 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 1.0 mL of the sample solution to 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 2 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the retention time is about 3 minutes, and the relative standard deviation for replicate injections is not more than 1.1%.
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 acetazolamide (C4H6N4O3S2) in the volume of Oral Suspension taken by the formula:
100(C/V)(rU / rS)
in which C is the concentration, in µg per mL, of USP Acetazolamide 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 1418
Pharmacopeial Forum: Volume No. 32(1) Page 44