Acoustic Monitoring of Lubrication and Compaction Effects on Tablet Performance Using Broadband Acoustic Resonance Dissolution Spectroscopy

Broadband Acoustic Resonance Dissolution Spectroscopy (BARDS) is a novel analytical technology based on the change in the acoustic phenomena observed when a material is added into a solvent. Addition of a solid material results in the introduction of air (gas) into the solvent, which changes the compressibility of the liquid system and reduces the velocity of the sound (resonance) contained therein. In this study, the behavior of tablets in water was monitored using the BARDS technique. Tablets investigated contained 10% metoclopramide HCl (model water-soluble drug) and a microcrystalline cellulose filler and were formulated with and without a lubricant (0.5% magnesium stearate) at a range of tensile strength and porosity properties. The BARDS frequency-time profile for lubricated tablets showed an extended profile, indicating a slower wetting and prolonged displacement of gas compared to those of tablets without a lubricant. BARDS frequency-time profiles were transformed into gas volume-time profiles from which the areas under the total gas volume and volume curve (AUVC) were calculated. Lubricated tablets displayed a greater AUVC compared with unlubricated tablets. A decrease in the AUVC was observed for tablets up to the yield pressure of the formulation. For unlubricated tablets compacted at lower pressures, the gas elimination phase displayed first-order rate elimination kinetics. However, for lubricated tablets and unlubricated tablets compacted at higher pressures, two phases of gas elimination were observed: an initial fast elimination phase followed by a slower terminal elimination phase. This preliminary analysis of BARDS profiles collected demonstrates the capability of BARDS to capture differences between tablet formulations manufactured under different conditions.