Edition: BP 2025 (Ph. Eur. 11.6 update)
Action and use
Quinolone antibacterial.
DEFINITION
Nalidixic Acid Oral Suspension is a suspension of Nalidixic Acid in a suitable flavoured vehicle.
The oral suspension complies with the requirements stated under Oral Liquids and with the following requirements.
Content of nalidixic acid, C12H12N2O3
92.5 to 107.5% of the stated amount.
IDENTIFICATION
To 5 mL add 30 mL of water and 20 mL of dilute sodium carbonate solution, mix and shake with two 30 mL quantities of chloroform; discard the chloroform layers. Acidify the aqueous solution with 5M hydrochloric acid, shake with 40 mL of chloroform, wash the chloroform layer with 10 mL of water to which has been added 0.5 mL of 5M hydrochloric acid, filter the chloroform layer through absorbent cotton and evaporate the filtrate to dryness. Dissolve the residue in sufficient 0.1M sodium hydroxide to produce a solution containing 0.0008% w/v of Nalidixic Acid. The light absorption of the solution, Appendix II B, in the range 230 to 350 nm exhibits two maxima, at 258 nm and 334 nm.
ASSAY
Dilute a weighed quantity containing 0.12 g of Nalidixic Acid to 100 mL with 0.01M sodium hydroxide, dilute 2 mL to 250 mL with 0.01M sodium hydroxide and measure the absorbance of the resulting solution at the maximum at 334 nm, Appendix II
B. Determine the weight per mL of the oral suspension, Appendix V G, and calculate the content of C12H12N2O3, weight in volume, taking 494 as the value of A(1%, 1 cm) at the maximum at 334 nm.
