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Category Antibacterial (first-generation cephalosporin).

          Cephalexin for Oral Suspension is a dry mixture of Cephalexin and one or more suitable buffers, colours, diluents, and flavours. It contains the equivalent of not less than 90.0 per cent and not more than 120.0 per cent of the labelled amount of C₁₆H₁₇N₃O₄S when constituted as directed in the labelling.

Strengths available 125 and 250 mg (anhydrous) per 5 ml.

Dose Adults: 1 to 4 g daily in divided doses every
           Children: 25 to 50 mg per kg of body weight daily in divided doses every 6 hours. For severe infections, these dosages may be doubled.

Contra-indication; Warning; Precaution; Additional information See under Cephalexin, p. 58.

Packaging and storage Cephalexin for Oral Suspension shall be kept in tightly closed containers and stored at a temperature not exceeding 30º, protected from light. After constitution, it should be used within the period stated on the label.

Labelling The label on the container states the quantity equivalent to the amount of anhydrous cephalexin.

Identification
          A. Shake a portion of the oral suspension, equivalent to 100 mg of cephalexin, with 70 ml of methanol, filter and evaporate the filtrate to dryness using a rotary evaporator. Dissolve the residue in the minimum
volume of a 1 per cent v/v solution of glacial acetic acid, decolourize if necessary by the addition of sufficient decolourizing charcoal, shake and filter. To 5 drops of the resulting solution, add 2 drops of a 1 per cent w/v solution of copper(II) sulfate and 1 drop of 2 M sodium hydroxide: an olive-green colour is produced.
          B. The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that in the chromatogram of the Standard preparation, as obtained in the Assay.

pH 3.0 to 6.0, in the suspension constituted as directed in the labelling (Appendix 4.11).

Water Not more than 2.0 per cent w/w (Karl Fischer Method, Appendix 4.12).

Assay Carry out the determination as described in the “High-pressure Liquid Chromatography” (Appendix 3.5).

Mobile phase, Standard preparation, Chromatographic system and Procedure Proceed as directed in the Assay under Cephalexin, p. 60.
          Assay preparation Transfer an accurately measured volume of Cephalexin for Oral Suspension, constituted as directed in the labelling, containing about 250 mg of cephalexin, to a 250-ml volumetric flask. Add 100 ml of water and shake for 30 minutes. Adjust to volume with water and filter. Dilute 25.0 ml of the filtrate to 50.0 ml with water.
          Calculation Calculate the content of C₁₆H₁₇N₃O₄S, in mg, in each ml of the constituted Oral Suspension taken, using the declared content of C₁₆H₁₇N₃O₄S in Cephalexin RS.

Other requirements Complies with the requirements described under “Oral Liquids” (Appendix 1.16).