Action and use
Penicillin antibacterial.
DEFINITION
Amoxicillin Veterinary Oral Powder is a mixture of Amoxicillin Trihydrate, Lactose Monohydrate or other suitable diluent and a stabilising agent.
The veterinary oral powder complies with the requirements stated under Veterinary Oral Powders and with the following requirements.
Content of amoxicillin, C16H19N3O5S
90.0 to 110.0% of the stated amount.
IDENTIFICATION
A. Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions.
(1) Dissolve a quantity of the veterinary oral powder containing the equivalent of 0.25 g of amoxicillin in sufficient sodium hydrogen carbonate solution to produce 100 mL.
(2) 0.25% w/v of amoxicillin trihydrate BPCRS in sodium hydrogen carbonate solution.
(3) 0.25% w/v of each of amoxicillin trihydrate BPCRS and ampicillin trihydrate BPCRS in sodium hydrogen carbonate solution.
CHROMATOGRAPHIC CONDITIONS
(a) Use a TLC silica gel silanised plate (Merck silanised silica gel 60 F254s (RP-18) plates are suitable).
(b) Use the mobile phase as described below.
(c) Apply 1 μL of each solution.
(d) Develop the plate to 15 cm.
(e) After removal of the plate allow it to dry in air, expose it to iodine vapour until spots appear and examine in daylight.
MOBILE PHASE
10 volumes of acetone and 90 volumes of a 15.4% w/v solution of ammonium acetate adjusted to pH 5.0 with glacial acetic acid.
SYSTEM SUITABILITY
The test is not valid unless the chromatogram obtained with solution (3) shows two clearly separated spots.
CONFIRMATION
The principal spot in the chromatogram obtained with solution (1) is similar in position, colour and size to that in the chromatogram obtained with solution (2).
B. Shake a quantity of the veterinary oral powder containing the equivalent of 0.5 g of amoxicillin with 5 mL of water for 5 minutes, filter, wash the residue first with absolute ethanol and then with ether and dry at a pressure not exceeding 0.7 kPa for 1 hour. Suspend 10 mg of the residue in 1 mL of water and add 2 mL of a mixture of 2 mL of cupri-tartaric solution R1 and 6 mL of water. A magenta colour is produced immediately.
C. Dissolve 0.1 mL of aniline in a mixture of 1 mL of hydrochloric acid and 3 mL of water. Cool the solution in ice and add 1 mL of a freshly prepared 20% w/v solution of sodium nitrite. Add the resulting mixture drop wise to a cold solution of 0.1 g of the residue obtained in test B in 2 mL of 5M sodium hydroxide. The solution becomes deep cherry-red and a copious dark brown precipitate is produced.
ASSAY
Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
(1) Add 80 mL of mobile phase A to a quantity of the veterinary oral powder containing the equivalent of 60 mg of amoxicillin and shake for 15 minutes. Mix with the aid of ultrasound for 1 minute, add sufficient mobile phase A to produce 100 mL, mix and filter (Whatman GF/C filter paper is suitable).
(2) 0.070% w/v of amoxicillin trihydrate BPCRS in mobile phase A.
(3) 0.0004% w/v of cefadroxil BPCRS and 0.003% w/v of amoxicillin trihydrate BPCRS in mobile phase A.
CHROMATOGRAPHIC CONDITIONS
(a) Use a stainless steel column (25 cm × 4.6 mm) packed with octadecylsilyl silica gel for chromatography (5 μm) (Hypersil 5 ODS is suitable).
(b) Use isocratic elution and the mobile phase described below.
(c) Use a flow rate of 1 mL per minute.
(d) Use an ambient column temperature.
(e) Use a detection wavelength of 254 nm.
(f) Inject 50 μL of each solution.
MOBILE PHASE
8 volumes of mobile phase B and 92 volumes of mobile phase A.
Mobile phase A: 1 volume of acetonitrile and 99 volumes of a 25% v/v solution of 0.2M potassium dihydrogen orthophosphate adjusted to pH 5.0 with 2M sodium hydroxide.
Mobile phase B: 20 volumes of acetonitrile and 80 volumes of a 25% v/v solution of 0.2M potassium dihydrogen orthophosphate adjusted to pH 5.0 with 2M sodium hydroxide.
SYSTEM SUITABILITY
The Assay is not valid unless, in the chromatogram obtained with solution (3), the resolution factor between the peaks due to amoxicillin and cefadroxil is at least 2.0. If necessary, adjust the composition of the mobile phase to achieve the required resolution.
DETERMINATION OF CONTENT
Calculate the content of C16H19N3O5S in the veterinary oral powder from the chromatograms obtained and from the declared content of C16H19N3O5S in amoxicillin trihydrate BPCRS.
LABELLING
The quantity of active ingredient is stated in terms of the equivalent amount of amoxicillin.
