Clay nanotubes as a novel multifunctional excipient for the development of directly compressible diclofenac potassium tablets in a SeDeM driven QbD environment

Halloysite is a unique biocompatible aluminosilicate clay mineral with powder particles predominantly comprising of concentrically rolled nanotubular aggregates. Some recent studies have also contributed to its prospective case in oral drug delivery and dosage forms albeit with limited commercial viability. In this study, we have investigated the use of halloysite nanotubes (HNTs) as a directly compressible multifunctional tableting excipient using SeDeM diagram expert tool.

SeDeM experimentations revealed that ~68% HNTs in the formulations were enough to be used as a directly compressible filler, binder, and disintegrant in diclofenac potassium formulations. In the next phase, a total of 8 formulations blends (IRF1–8) of diclofenac potassium (50 mg) with HNTs and Starch 1500® were prepared in different ratio using simple lattice mixture design and all were found satisfactory for direct compression. Compressed tablets (167 mg) had narrow weight variation (SD = ± 1.78 mg), good hardness (~9–9.5 kg), acceptable friability (<0.7%) and fast disintegration time (<1.5 min). Moreover, the cumulative dissolution at 1 h in phosphate buffer pH 6.8 was found compliant with the compendial criteria (> 92% against 75%). The dissolution profile was best fitted with Peppas-Sahlin model with Fickian diffusion as the only mechanism. f2 similarity test revealed that almost all the tablets were pharmaceutical equivalent to the marketed formulation of the drug.

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A shelf-life of ~34 months was found upon long-term stability testing of the optimized formulation. This study demonstrates that this novel and economically viable clay material has a strong potential for commercial use in tableting of drug by direct compression. More on clay nanotubes