Near-infrared FT-Raman spectroscopy as a rapid analytical tool for the determination of diltiazem hydrochloride in tablets.

This study was performed to develop a fast and reliable analytical method for the quantitative determination of diltiazem hydrochloride in tablets. HPLC is currently the preferred method, but is time consuming due to extensive sample preparation. FT-Raman spectroscopy was used to quantitatively analyse diltiazem hydrochloride in commercially available tablets (Tildiem) and in experimental tablets prepared at lab-scale. The percentage of diltiazem hydrochloride in each tablet was determined by calculating-after vector normalisation-the total peak area of the spectral band between 1625 and 1560 cm(-1). No spectral interference from tablet excipients was seen at this spectral band. After FT-Raman spectroscopy the same samples were analyzed based on the HPLC method described in the USP XXIV. The drug dosage per tablet obtained from the vibrational spectroscopy method correlated well with the results obtained using HPLC analysis for both the commercial tablets (HPLC: 63.57+/-0.13 mg; Raman: 63.28+/-0.26 mg (n=50)) and the experimental tablets (HPLC: 181.02+/-0.25 mg; Raman: 181.22+/-0.35 mg (n=50)). FT-Raman is a reliable alternative for the HPLC method to quantify the amount of diltiazem hydrochloride in tablets. The spectroscopic method is faster because it eliminates sample pre-treatment. Furthermore the FT-Raman method has an additional advantage of not requiring solvents.