Abstract NMR relaxometry proved to be a powerful tool that provides useful information on the molecular dynamics of different pharmaceutical materials. The proton NMR relaxometry was measured using low-field NMR equipment. The aim of this work was to evaluate the interaction of different drugs in pharmaceutical systems, such as: propranolol (POP) and atorvastatin (ATV) in tablets with Tapioca Starch (TS); POP in Rosa Mosqueta oil nanoemulsion (NE); and papain in carboxymethylcelulose (CMC) hydrogel, using the proton spin-lattice relaxation time parameter. The spin-lattice relaxation measurements (T1H) were done through the inversion-recovery pulse sequence and the spin-spin relaxation measurements (T2H) were done by two pulse sequences, one was Magic-Sandwich Eco (MSE) and the other was Carr-Purcell-Meiboom-Gill (CPMG). From the analyses of T1H data it was concluded that there was an interaction between the drugs and TS in the tablets, which is explained by the increase of T1H values. The evaluation of T2H relaxation time of NE confirmed a correlation between NE phases and it was observed that POP was effectively distributed in water phase. From the structure of CMC hydrogel it was observed that papain interacted with free water molecules of the hydrogel. This study confirmed that NMR relaxometry can be used to characterize the drug delivery systems.
Keywords Relaxometry, spin-lattice relaxation time, spin-spin relaxation time, Pharmaceutical forms.