Application of near infrared reflectance spectroscopy (NIRS) to several antibiotic compounds

The possibility of applying near-infrared reflectance spectroscopy (NIRS) to the qualitative and quantitative control of several antibiotics was investigated. Samples of amorphous sodium ampicillin, gentamycin sulphate, erythromycin ethylsuccinate, erythromycin stearate, amorphous miokamycin and rifaximin were analysed. Some were analysed as primary material, others half-processed (erythromycin ethylsuccinate in granules at different concentrations of active ingredient) and others as the finished pharmaceutical product (rifaximin cream). The results were both qualitatively and quantitatively satisfactory. The distinction between amorphous or crystalline sodium ampicillin and ampicillin trihydrate and between the different erythromycin ethylsuccinate granules was intersting. It was confirmed that NIRS can be successfully applied to the quantitative control of solid and fluid (e.g. rifaximin cream) antibiotics forms.