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NALIDIXIC ACID

Category Antibacterial.

      Nalidixic Acid contains not less than 98.0 per cent and not more than 102.0 per cent of C12H12N2O3, calculated on the dried basis.

Description White to very pale yellow, crystalline powder; odourless.

Solubility Very slightly soluble in water and in ether; soluble in chloroform, in dichloromethane and in solutions of fixed alkali hydroxides and carbonates; slightly soluble in acetone, in ethanol, in methanol, and in toluene.

Contra-indication; Warning; Precaution See under Norfloxacin, p. 133.

Additional information

      1. The drug should not be used in the treatment of systemic infections where high serum and tissue concentrations of antibacterial agents are desirable.

      2. To minimize the development of bacterial resistance, patients should be carefully instructed not to omit doses of the drug, especially during the first few days of therapy.

See also under Norfloxacin, p. 133.

Packaging and storage Nalidixic acid shall be kept in tightly closed containers, protected from light.

Identification

      A. The infrared absorption spectrum is concordant with the spectrum obtained from Nalidixic Acid RS (Appendix 2.1) or with the reference spectrum of Nalidixic Acid.

      B. The ultraviolet absorption spectrum of a 0.0005 per cent w/v solution in 0.1 M sodium hydroxide, when observed between 230 and 350 nm, exhibits two maxima at 258 and 334 nm. The ratio of the absorbances measured at 258 nm to that measured at 334 nm is 2.2 to 2.4 (Appendix 2.2).

Melting range 225º to 231º (Appendix 4.3).

Loss on drying Not more than 0.5 per cent w/w after drying at 105º for 2 hours (Appendix 4.15).

Sulfated ash Not more than 0.10 per cent w/w (Appendix 5.3).

Heavy metals Not more than 20 ppm (Method II, Appendix 5.2). Use 1.0 g; for the Standard Preparation, use 2 ml of lead standard solution (10 ppm Pb).

Chromatographic purity Carry out the test as described in the “Thin-layer Chromatography” (Appendix 3.1), using precoated high-performance thin-layer chromatography silica gel GF254 as the stationary phase and a mixture of 70 volumes of ethanol, 20 volumes of chloroform and 10 volumes of 5 M ammonia as the mobile phase.

      Standard preparations Prepare a solution of Nalidixic Acid RS in chloroform containing 1.0 mg per ml. Dilute quantitatively with chloroform to obtain Standard preparations having the following composition:

      Test preparation Dissolve an accurately weighed quantity of the test substance in chloroform to obtain a solution containing 20 mg per ml. 

      Procedure Apply separately to the plate, 10 μl of each of Test preparation and Standard preparations. After removal of the plate, allow it to dry with the aid of warm circulating air and examine under ultraviolet light (254 nm). Compare the intensities of any secondary spots observed in the chromatogram of the Test preparation with those of the principal spots in the chromatograms of the Standard preparations: no secondary spot is more intense than the principal spot obtained from the Standard preparation A (0.5 per cent), and the sum of the intensities of all secondary spots obtained from the Test preparation does not exceed 1.0 per cent.

Assay Dissolve about 150 mg of Nalidixic Acid, accurately weighed, in 25 ml of dimethylformamide. Protect the contents against atmospheric carbon dioxide by using a cover. With the aid of a magnetic stirrer, titrate with 0.1 M tetrabutylammonium hydroxide VS, using thymolphthalein TS as indicator or determining the endpoint potentiometrically (Appendix 6.1). Perform a blank determination, and make any necessary correction. Each ml of 0.1 M tetrabutylammonium hydroxide is equivalent to 23.22 mg of C12H12N2O3.

MONOGRAPHS • NALIDIXIC ACID
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หมายเหตุ / Note : TP II 2011 PAGE 129-130