Ampicillin and Cloxacillin Intramammary Infusion (DC)
DEFINITION
Ampicillin Trihydrate and Cloxacillin Benzathine Intramammary Infusion (Dry Cow) is a sterile suspension of Ampicillin Trihydrate and Cloxacillin Benzathine in a suitable vehicle, containing suitable suspending agents.
The intramammary infusion complies with the requirements stated under Intramammary Infusions and with the following requirements.
Content of ampicillin, C16H19N3O4S
90.0 to 110.0% of the stated amount.
Content of cloxacillin, C19H18ClN3O5S
90.0 to 110.0% of the stated amount.
IDENTIFICATION
A. Extract a quantity containing the equivalent of 0.25 g of ampicillin with three 15-mL quantities of petroleum spirit (boiling range, 120° to 160°). Discard the extracts, wash the residue with 10 mL of ether and dry in a current of air. Shake with 10 mL of chloroform and filter. Retain the filtrate. Wash the residue with two 5-mL quantities of chloroform and dry at room temperature at a pressure of 2 kPa. The infrared absorption spectrum of the residue, Appendix II A, is concordant with the reference spectrum of ampicillin trihydrate (RSV 06).
B. Wash the filtrate obtained in test A with two 5-mL quantities of water, dry the chloroform layer with anhydrous sodium sulfate, filter and dilute the filtrate to 20 mL with chloroform. The infrared absorption spectrum of the resulting solution, Appendix II A, is concordant with the reference spectrum of cloxacillin benzathine (RSV 12).
TESTS
Water
Not more than 3.0% w/w, Appendix IX C. Use 1.5 g and a mixture of 70 volumes of chloroform and 30 volumes of anhydrous methanol as the solvent.
ASSAY
Express, as far as possible, weigh and mix the contents of 10 containers. Extract a quantity of the mixed contents containing the equivalent of 60 mg of ampicillin with three 15-mL quantities of petroleum spirit (boiling range, 120° to 160°) previously saturated with ampicillin trihydrate and cloxacillin benzathine. Discard the extracts, wash the residue with ether previously saturated with
ampicillin trihydrate and cloxacillin benzathine, dry in a current of air, dissolve in 50 mL of methanol and dilute to 100 mL with water. Centrifuge and use the clear supernatant liquid (solution A).
For ampicillin
Dilute 2 mL of solution A to 50 mL with buffered copper sulfate solution pH 5.2, transfer 10 mL to a stoppered test tube and heat in a water bath at 75° for 30 minutes. Rapidly cool to room temperature, dilute to 20 mL with buffered copper sulfate solution pH 5.2 and measure the absorbance of the resulting solution at the maximum at 320 nm, Appendix II B, using in the reference cell the unheated buffered solution of the infusion. Calculate the content of C16H19N3O4S in a container of average content from the absorbance obtained by carrying out the operation at the same time using 2 mL of a solution prepared by dissolving 60 mg of anhydrous
ampicillin BPCRS in 100 mL of a 50% v/v solution of methanol, diluting to 50 mL with buffered copper sulfate solution pH 5.2, and beginning at the words ‘transfer 10 mL…’ and from the declared content of C16H19N3O4S in anhydrous ampicillin BPCRS.
For cloxacillin
Dilute 2 mL of solution A to 100 mL with 1M hydrochloric acid. Measure the absorbance of the resulting solution at the maximum at 350 nm, Appendix II B, at 20° after exactly 12 minutes, using 1M hydrochloric acid in the reference cell. Calculate the content of C19H18ClN3O5S in a container of average content from the absorbance obtained by carrying out the operation at the same time
using 2 mL of a solution prepared by dissolving 0.165 g of cloxacillin benzathine BPCRS in 100 mL of a 50% v/v solution of methanol and from the declared content of C19H18ClN3O5S in cloxacillin benzathine BPCRS.
LABELLING
The label states the quantity of Ampicillin Trihydrate in terms of the equivalent amount of ampicillin and the quantity of Cloxacillin Benzathine in terms of the equivalent amount of cloxacillin.
