Toward predicting tensile strength of pharmaceutical tablets by ultrasound measurement in continuous manufacturing

TL;DR

This study demonstrates that ultrasound measurement can reliably predict the tensile strength of pharmaceutical tablets in a continuous manufacturing setting, offering a fast, non-destructive alternative to traditional testing methods.

Contribution

It introduces a novel ultrasound-based approach for predicting tablet tensile strength, integrating it into continuous manufacturing for real-time quality assessment.

Findings

Ultrasound speed decreases with increased shear strain.

Ultrasound testing differentiates tablets with similar formulations but different processing conditions.

A predictive strategy using Young's modulus and tensile strength models is proposed.

Abstract

An ultrasound measurement system was employed as a non-destructive method to evaluate its reliability in predicting the tensile strength of tablets and investigate the benefits of incorporating it in a continuous line, manufacturing solid dosage forms. Tablets containing lactose, acetaminophen, and magnesium stearate were manufactured continuously and in batches. The effect of two processing parameters, compaction force and level of shear strain were examined. Young's modulus and tensile strength of tablets were obtained by ultrasound and diametrical mechanical testing, respectively. It was found that as the blend was exposed to increasing levels of shear strain, the speed of sound in the tablets decreased and the tablets became both softer and mechanically weaker. Moreover, the results indicate that two separate tablet material properties (e.g., relative density and Young's modulus) are necessary in order to predict tensile strength. A strategy for hardness prediction is proposed that uses the existing models for Young's modulus and tensile strength of porous materials. Ultrasound testing was found to be very sensitive in differentiating tablets with similar formulation but produced under different processing conditions (e.g., different level of shear strain), thus, providing a fast, and non-destructive method for hardness prediction that could be incorporated to a continuous manufacturing process.