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Category  Antibacterial. 

      Erythromycin Delayed-release Tablets contain not less than 90.0 per cent and not more than 120.0 per cent of the labelled amount of C₃₇H₆₇NO₁₃. 

Strength available  250 mg.

Dose  Adults:  250 mg every 6 hours.  In severe infections, dosage may be increased up to 4 g daily. Children:  30 to 50 mg per kg of body weight or 0.9 to 3 g per m² of body surface area (Appendix 1.17) daily given in 4 equally divided doses and may be doubled in severe infections. 

Contra-indication; Warning; Precaution  See under Erythromycin, p. 99. 

Packaging and storage  Erythromycin Delayed-release Tablets shall be kept in tightly closed containers, protected from light. 

Identification

      A. Shake a portion of the powdered tablets containing 100 mg of erythromycin with 5 ml of chloroform, decolourize, if necessary, with decolorizing charcoal, filter, and evaporate the filtrate to dryness.  The infrared absorption spectrum of the residue, after drying at a pressure not exceeding 0.7 kPa (about 5 Torr), is concordant with the spectrum obtained from Erythromycin RS(Appendix 2.1) or with the reference spectrum of  Eryth romycin.

      B. Carry out the test as described in the “Thin-layer Chromatography” (Appendix 3.1), using silica gel G as the coating substance and a mixture of 17 volumes of methanol and 3 volumes of chloroform as the mobile phase but developing the chromatogram in an unlined chromatographic chamber.  Apply separately to the plate, 10 μl of each of the following solutions.  For solution (A), shake a portion of the powdered tablets with methanol to obtain a concentration of 2.5 mg of erythromycin per ml.  Solution (B) contains 2.5 mg/ml of Erythromycin RS in methanol.  After removal of the plate, allow it to dry in air.  Spray the plate with a mixture of 18 volumes of absolute ethanol, 1 volume of anisaldehye and 1 volume of sulfuric acid.  Heat the plate at 100º for 10 minutes.  Erythromycin appears as blackto-purple spots.  The principal spots in the chromatogram obtained from solution (A) correspond to those obtained from solution (B).

      C. Dissolve a portion of the powdered tablets containing 3 mg of erythromycin as completely as possible in 2 ml of acetone and add 2 ml of hydrochloric acid:  an orange colour is produced which changes to red and then to deep purplish red.  Add 2 ml of chloroform and shake:  the chloroform layer becomes purple. 

Water  Not more than 10.0 per cent w/w (Karl Fischer Method, Appendix 4.12).  Use 20 ml of methanol containing 10 per cent of imidazole in place of methanol in the titration vessel. 

Dissolution  Carry out Method B described in the “Dissolution” (Appendix 4.24).

      Apparatus 1:  100 rpm.

      Times:  60 minutes, stage 1.

                   60 minutes, stage 2. 

      Acid stage  Using 900 ml of simulated gastric fluid TS (prepared without pepsin) in place of 0.1 M hydrochloric acid, conduct this stage of the test for 60 minutes, and do not perform an analysis of the medium. 

      Buffer stage  Using 900 ml of phosphate buffer pH 6.8, conduct this stage of the test for 60 minutes. 

      Test solution  If necessary, dilute a filtered portion of the test solution with Dissolution medium to obtain a solution having a concentration of about 0.28 mg of erythromycin per ml, and mix. 

      Procedure  Transfer a 2.0-ml portion of the Test solution to a suitable separator.  Add 6 ml of pH 1.2 buffer, and 8 ml of a solution of bromocresol purple, prepared by dissolving 1 g of bromocresol purple in 100 ml of phosphate buffer pH 4.5 and mix.  Extract with 40.0 ml of chloroform.  Determine the amount of C₃₇H₆₇NO₁₃ dissolved from absorbances at a maximum at about 410 nm using the chloroform extracts (Appendix 2.2).  Similarly prepare a standard solution having a known concentration of Erythromycin RS and treat similarly. 

Assay  Place not less than four Erythromycin Tablets in a high-speed glass blender jar with 200 ml of methanol and blend for 3 minutes.  Add 300 ml of Buffer 2 and blend for 3 minutes.  Proceed as directed under the microbiological assay of Erythromycin according to the “Microbiological Assay of Antibiotics” (Appendix 6.10).

Other requirements  Comply with the requirements described under “Tablets” (Appendix 1.16).