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Category  Antibacterial.

               Dicloxacillin Sodium for Oral Suspension is a dry mixture of Dicloxacillin Sodium and one or more suitable buffers, colours, flavours, and preservatives.  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 dicloxacillin (C₁₉H₁₇Cl₂N₃O₅S) when constituted as directed.

Strength available  62.5 mg (base) and 125 mg (base) per 5 mL.

Dose  Dosage of Dicloxacillin Sodium for Oral Suspension is expressed in terms of dicloxacillin base.
Adults and children 40 kg of body weight and over:  125 to 500 mg every 6 hours.
Children up to 40 kg of body weight:  3.125 to 6.25 mg per kg of body weight every 6 hours.

Contra-indication; Warning; Precaution; Additional information  See under Dicloxacillin Sodium.

Packaging and storage  Dicloxacillin Sodium for Oral Suspension shall be kept in tightly closed containers and stored at a temperature not exceeding 30°. 

Labelling  The label on the container states (1) the quantity equivalent to the amount of dicloxacillin; (2) the expiration date.

Identification  The retention time of the major peak in the chromatogram of the Assay preparation corresponds to that of the Standard preparation, as obtained in the Assay.

pH  4.5 to 7.5, 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 “Liquid Chromatography” (Appendix 3.5). 
     Diluent  A solution containing 2 mg per mL of dibasic potassium phosphate and 8 mg per mL of monobasic potassium phosphate.
     Buffer  Prepare a solution containing 2.72 mg per mL of monobasic potassium phosphate, adjusted with 8 M potassium hydroxide to a pH of 4.9 to 5.1.
     Standard preparation  Transfer about 52 mg of Dicloxacillin Sodium RS, accurately weighed, to a
250-mL volumetric flask, add 40.0 mL of dimethylformamide, 10.0 mL of ethanol, and 100 mL of Diluent, and shake for 5 minutes or until completely dissolved.  Dilute with Diluent to volume, and mix.  Filter through a 0.45-µm membrane filter and use the filtrate.  (Note  Use the standard preparation promptly, or refrigerate and use on the day prepared.)
     Assay preparation  Constitute Dicloxacillin Sodium for Oral Suspension as directed in the labelling.  Transfer an accurately weighed portion of the constituted suspension, equivalent to about 50 mg of dicloxacillin, to a 250-mL volumetric flask.  Add 40.0 mL of dimethylformamide and 10.0 mL of ethanol, and shake for 15 minutes.  Add 100 mL of Diluent, and shake for an additional 30 minutes.  Dilute with Diluent to volume and mix.  Filter through a 0.45-µm membrane filter and use the filtrate.  (Note  Use the assay preparation promptly, or refrigerate and use on the day prepared.
     Mobile phase  Acetonitrile and Buffer (26:74)
     Chromatographic System
        DETECTOR  Ultraviolet light (225 nm).
        COLUMN  A stainless steel column (15 cm × 4.6 mm), packed with octadecylsilane chemically bonded to porous silica or ceramic microparticles (5 µm).
        FLOW RATE  1.5 mL per minute
System Suitability
        SAMPLE  Standard preparation
Suitability requirements
     CAPACITY FACTOR  Between 4 and 11 for the dicloxacillin peak.
     COLUMN EFFICIENCY  Not less than 700 theoretical plates for the dicloxacillin peak.
     SYMMETRY FACTOR  Not more than 2.0 for the dicloxacillin peak.
     RELATIVE STANDARD DEVIATION  Not more than 2.0 per cent for the dicloxacillin peak.
Procedure  Separately inject equal volumes (about 10 mL) of Standard preparation and Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. 
Calculation  Calculate the content of C₁₉H₁₇Cl₂N₃O₅S in the portion of the constituted Oral Suspension taken, using the declared content of C₁₉H₁₇Cl₂N₃O₅S in the Dicloxacillin Sodium RS.

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