Quality control of tablets by Near Infrared (NIR)-Spectroscopy

Today, NIR-spectroscopy is an established analytical technique not only in the identification of raw materials but also in the quantification of active ingredients in tablets. In this work calibration models were set up with tablets of the same active ingredient but of miscellaneous origin and manufacturess. Consequently the tablets had different excipients and appearance. The pharmaceutical preparations used included atenolol 100 mg tablets, enalapril 20 mg tablets and acetylsalicylic acid (ASS) tablets of different dosage units. In order to proof if the calibration models set up are generally feasible the assay declared by the manufacturer was used to calculate the partial least square (PLS) calibration. With respect to enalapril tablets simultaneous analysis by HPLC, according to USP 26 was carried out. It was investigated if such methods allow a determination of active ingredients in tablets within limits of +/- 10% of declaration. It was shown that it is possible to set up calibration models to quantify active ingredients in tablets independent of adjuvants or optical appearance. Additionally it could be shown that NIR-spectroscopy is also applicable to determine the concentration of active ingredients in blister-packed tablets.