Atenolol Compounded Oral Suspension, Veterinary
DEFINITION
Atenolol Compounded Oral Suspension, Veterinary contains NLT 90.0% and NMT 110.0% of the labeled amount of atenolol (C14H22N2O3). Prepare Atenolol Compounded Oral Suspension, Veterinary 25 mg/mL as follows (see Pharmaceutical Compounding—Nonsterile Preparations 795).
Atenolol powder 2.5 g
Vehicle: a 1:1 mixture of Ora-Plusa and Ora-Sweet SFa, a sufficient quantity to make 100 mL
a   Perrigo Pharmaceuticals, Allegan, MI.
Pour the Atenolol powder into a suitable container. Wet the powder with a small amount of Vehicle, and triturate to make a smooth paste. Add the Vehicle to make the contents pourable. Transfer the contents stepwise and quantitatively to a calibrated container using the remainder of the Vehicle. Add sufficient Vehicle to bring to final volume. Shake to mix well.
ASSAY
•  Procedure
Solution A:  25 mM sodium phosphate adjusted with phosphoric acid to a pH of 3.0
Mobile phase:  Acetonitrile and Solution A (15:85). Filter, and degas.
Solution B:  Water adjusted with phosphoric acid to a pH of 3.0
Solution C:  Methanol and Solution B (50:50)
Standard stock solution:  25 mg/mL of USP Atenolol RS in Solution C. Mix well, and sonicate for 3 min. Store at 2–8.
Standard solution:  Transfer 2.0 mL of the Standard stock solution to a 1-L volumetric flask, and add 0.5 mL of Solution C. Dilute with Solution B to volume, and mix well. Centrifuge a portion of the resultant solution for 5 min at 14,000 rpm, and use the supernatant. Protect from light, and store at 2–8.
Sample solution:  Shake thoroughly each bottle of Oral Suspension, Veterinary. Transfer 2.0 mL of Oral Suspension, Veterinary to a 1-L volumetric flask, and add 0.5 mL of Solution C. Dilute with Solution B to volume. Centrifuge a portion of the solution for 5 min at 14,000 rpm, and use the supernatant. Protect from light, and store at 2–8.
Chromatographic system 
Mode:  LC
Detector:  UV 227 nm
Column:  4.6-mm × 25-cm; 5-µm packing L1
Temperatures 
Column:  30
Autosampler:  5
Flow rate:  0.7 mL/min
Injection volume:  20 µL
System suitability 
Sample:  Standard solution
[Note—The retention time for atenolol is about 5.1 min. ]
Suitability requirements 
Tailing factor:  NMT 2.0
Relative standard deviation:  NMT 2.0% for replicate injections
Analysis 
Samples:  Standard solution and Sample solution
Calculate the percentage of the labeled amount of atenolol (C14H22N2O3) in the portion of Oral Suspension, Veterinary taken:
Result = (rU/rS) × (CS/CU) × 100

rU== peak response of atenolol from the Sample solution
rS== peak response of atenolol from the Standard solution
CS== concentration of atenolol in the Standard solution (mg/mL)
CU== nominal concentration of atenolol in the Sample solution (mg/mL)
Acceptance criteria:  90.0%–110.0%
SPECIFIC TESTS
•  pH 791: 9.1–10.1
ADDITIONAL REQUIREMENTS
•  Packaging and Storage: Package in tight, light-resistant containers. Store at 2–8 or at controlled room temperature.
•  Labeling: Label it to indicate that it is to be well shaken before use, and to state the Beyond-Use Date. Label it to state that it is for veterinary use only.
•  Beyond-Use Date: NMT 90 days after the date on which it was compounded when stored at 2–8 or controlled room temperature
•  USP Reference Standards 11
USP Atenolol RS Click to View Structure
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Jeanne H. Sun, Pharm.D.
Associate Scientific Liaison
(301) 230-3361
(CMP2010) Compounding
Reference Standards RS Technical Services
1-301-816-8129
rstech@usp.org
USP38–NF33 Page 2308
Pharmacopeial Forum: Volume No. 39(5)