Background: The drug-excipient compatibility studies were carried out with the possible excipients viz. Tween 80, Carbopol 940, chitosan, sodium alginate, and polycaprolactone (PCL) for their possible use in the formulation of eugenol loaded nanoemulsion gels and nanoparticles.

Methods: The eugenol-excipient compatibility studies were carried out by visual observations, differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), and high-performance thin-layer chromatography (HPTLC).

Results: No notable change was observed in the samples on visual observation. From the results of the DSC studies, to a much extent, it was assumed that eugenol was not subjected to any interaction with the selected excipients for the proposed nanoemulsion gel and nanoparticles. But in some cases viz. polycaprolactone and Carbopol, though not to a significant level, slight deviation of the nature and position of the endothermic peaks of eugenol were observed. The results of the IR spectroscopy confirmed the compatibility of eugenol with Tween 80, Carbopol 940, chitosan, sodium alginate, and polycaprolactone. The retention factor of the HPTLC densitogram peaks for all the physical mixtures was well within the retention factor (Rf) value range observed for pure eugenol.

Conclusions: The study results confirmed that eugenol is compatible with the selected excipients for the development of nanoemulsion gels and nanoparticles.

Keywords: Eugenol, Chitosan, Sodium alginate, Poly-ε-caprolactone, Tween 80, Carbopol 940