Background: Alendronate sodium (the sodium salt of 4-Amino-1-hydroxy-1-bisphosphonic
acid) is a potent anti-resorptive drug that is widely used for the treatment of osteoporosis and Paget’s
disease. Its analysis is challenging due to the lack of chromophore in its chemical structure. This study
describes a quick and simple attenuated total reflectance (ATR) Fourier transform infrared (FTIR)
spectroscopic method for the determination of alendronate in tablets.
Method: Nicolet™ iS5 FTIR spectrometer equipped with iD5 ATR accessory featuring a top plate
diamond crystal with a fixed angel of incidence of 42° and controlled by OMNIC software was used for
spectra collection. TQ Analyst software was used for data processing. The calibration model was based
on Beer’s Law using the peak at 1543.83 cm-1
corresponding to the phosphate group of alendronate.
Results: The method was found to be linear in the range of 0.5-5% w/w with excellent correlation
coefficient of 0.9999. The method was validated according to the International Conference on
Harmonization (ICH) guidelines. Limit of detection and limit of quantification values were 0.05% w/w
and 0.14% w/w, respectively. The relative standard deviations for intraday precision and interday
precision for five replicate measurements were 2.32% and 2.58%, respectively. Mean percentage recovery
was found to be 99.73±1.33%. The validated method was used for the quantification of alendronate in
tablets and percentage of labelled amount was found to be 101.11±1.9%.
Conclusion: The ATR accessory gave the advantage of very simple sample preparation that and less
analysis time. The phosphate peak at 1543.83 cm-1
in the IR spectrum was specific for alendronate. Tablet
excipients showed no interference with the analysis. The validated ATR-FTIR method was found to be
suitable for routine analysis of alendronate in tablet.