Amoxicillin Capsules

General Notices

Action and use

Penicillin antibacterial.

Definition

Amoxicillin Capsules contain Amoxicillin Trihydrate.

The capsules comply with the requirements stated under Capsules and with the following requirements.

Content of amoxicillin, C16H19N3O5S

92.5 to 110.0% of the stated amount.

Identification

Shake a quantity of the contents of the capsules 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. The residue complies with the following tests.

A. The infrared absorption spectrum, Appendix II A, is concordant with the reference spectrum of amoxicillin trihydrate (RS 011).
B. Carry out the method for thin-layer chromatography, Appendix III A, using the following solutions.
(1) Dissolve a quantity of the residue in sufficient sodium hydrogen carbonate solution to produce a solution containing the equivalent of 0.25% w/v of amoxicillin.
(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 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 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).

Tests

Related substances

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 mixed capsule contents containing the equivalent of 0.15 g 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.
(2) Dilute 1 volume of solution (1) to 100 volumes with 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 gradient 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
Mobile phase A1 volume of acetonitrile and 99 volumes of a pH 5.0 buffer solution prepared in the following manner. To 250 mL of 0.2m potassium dihydrogen orthophosphate add 2m sodium hydroxide until the pH reaches 5.0 and add sufficient water to produce 1000 mL.
Mobile phase B20 volumes of acetonitrile and 80 volumes of the pH 5.0 buffer solution.

Equilibrate the column with a mobile phase ratio A:B of 92:8. Inject solutions (1) and (2) and start the elution isocratically with the chosen mobile phase. Immediately after elution of the amoxicillin peak start a linear gradient elution to reach a mobile phase ratio A:B of 1:100 over a period of 25 minutes. Continue the chromatography with mobile phase B for 15 minutes then equilibrate the column for 15 minutes with the mobile phase chosen originally. Inject mobile phase A and use the same elution gradient to obtain a blank.

system suitability

The test 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.

limits

In the chromatogram obtained with solution (1):

the area of any secondary peak is not greater than 1.5 times the area of the principal peak in the chromatogram obtained with solution (2) (1.5%);

the area of not more than one secondary peak is greater than the area of the principal peak in the chromatogram obtained with solution (2) (1%);

the area of any other secondary peak is not greater than the area of the principal peak in the chromatogram obtained with solution (2) (1%).

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 mixed contents of 20 capsules 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 A1 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 B20 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 capsules 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.