Combined approach of FTIR imaging and conventional dissolution tests applied to drug release.

A new method is developed to study drug release using a combination of FTIR imaging and conventional dissolution tests. FTIR imaging in attenuated total reflection (ATR) mode allows simultaneous measurements of the distribution of different components in the tablet, e.g., drug, polymer and water as a function of time. These imaging measurements were carried out in a combined compaction and flow-through cell, which was linked to a UV detector to quantify the amount of dissolved drug. In this way, changes in drug concentration in the aqueous solution can be studied similarly to the conventional dissolution test. This combination provides quantitative information of changes in both the tablet and the liquid phase. A tablet composed of hydroxypropyl methylcellulose (HPMC) and niacinamide was prepared and analysed using this setup. Mathematical processing of the measured spectra with a partial least squares (PLS) calibration was utilised for accurate quantitative analysis of the concentrations of different components. The results of FTIR imaging and the dissolution test are compared.