Separation and determination of impurities in paracetamol, codeine and pitophenone in the presence of fenpiverinium in combined suppository dosage form

- The method for separation of paracetamol, codeine, pitophenone and their impurities and fenpiverinium is described.
- The sample preparation procedure from the suppository drug form was developed.
- The main degradation product of pitophenone was confirmed.
- The method was validated and could be used as a routine purity testing method.