Comparative study on the rheological properties and tablettability of various APIs and their composites with titanate nanotubes

The present study aimed to investigate the processability of API-titanate nanotube composites into direct compressed tablets and therefore to reveal the benefits of the composite formation provided in tablet manufacturing. Diltiazem hydrochloride, diclofenac sodium, atenolol, hydrochlorothiazide and their 1:1 ratio composites formed with titanate nanotubes (TNTs) were used for the comparative investigations focusing on flowability, compaction behaviour and post-compressional property measurements. The flowability was studied by measuring the flow time, the angle of repose, the Hausner Ratio and the Compressibility Index, while the compaction properties were estimated by the use of out-of-the-die method applying Kawakita and Walker models. The tablet properties were described by determining the apparent tablet density, the breaking strength and the disintegration time. Based on the experimental results, the composites have superior flowability and display better compactibility and compressibility than the pure APIs. These findings were supported by the more favourable post-compressional properties shown by the composite containing tablets. However, the measurements also revealed that the advantageous effect of TNTs on drug tablettability depends on the efficiency of the incorporation process.