For the purpose of performing simultaneous determinations of diclofenac
sodium and rabeprazole sodium in tablet dosage form, an easy-to-use,
cost-effective, accurate, precise and validated diffuse reflectance infrared
fourier transform spectroscopy method has been developed. Measurement of the
spectral wave number of the infrared band corresponding to the NH2
group stretch at 3388 cm-1 for diclofenac sodium and the S=O group
at 1274 cm-1 for rabeprazole sodium is included in the newly
developed approach. The approach was found to be linear over the range of 1%-6%
weight by weight for diclofenac sodium and 0.2%-1.2% weight by weight for
rabeprazole sodium, and demonstrated a correlation coefficient (r2)
of 0.991 and 0.991, respectively. The method that was developed was validated
to ensure that it met the requirements set forth by the ICH regarding
linearity, precision, accuracy, limit of detection, and limit of quantitation.
In addition to this, the behaviours of deterioration of the solid state of
diclofenac sodium and rabeprazole sodium were investigated by exposing them to
photolysis, sunlight and thermal degradation.