Effect of Sodium C-Tetra(propyl)resorcin[4]tetrasulfonate (Na4PRA) on Antituberculosis Drugs as Seen by Diffusometry and NMR Spectroscopy

The present study investigates the physicochemical behavior of the first-line anti-tuberculosis drugs isoniazid (INH) and ethambutol, in the form of dihydrochloride (E·(HCl)2), in aqueous solutions containing the synthetic macrocyclic resorcinarene, C-tetra(propyl)resorcin[4]tetrasulfonate (Na4PRA) at 298.15 K. Taylor dispersion experiments were conducted to determine the ternary diffusion coefficients of these systems, offering valuable insights into their transport properties. Non-zero cross-diffusion coefficients (D12 and D21) demonstrate significant coupled transport, collectively indicating interactions between these antibiotics and the resorcinarene host. This behavior is highly consistent with the formation of a host–guest complex. These diffusion measurements were complemented by NMR spectroscopy, which confirmed the formation of host–guest complexes between the respective drugs and this resorcinarene, Na4PRA.