This work aimed to prepare and characterize formulations containing the RuBPY free and loaded in PNP prepared by nanoprecipitation and to verify if its formulation induces relaxation in isolated aorta from 2K‐1C and 2K rats. We have analyzed the maximum effect (ME) and potency (pD2). P values ¡Ü0.05 were significant. The average diameter, polydispersity index (pdI) and encapsulation efficiency of RuBPY were determined. Vascular reactivity experiments were performed on denuded aorta contracted with phenylephrine. The better PNP obtained presented 84.12nm average diameter and pdI 0.113. After RuBPY loaded PNP presented 104.9±1.86 nm and pdI 0.123±0.03. The developed PNP were able to encapsulate around 44.8% of RuBPY. Formulation containing RuBPY induced relaxation with similar ME and pD2 in 2K (ME:98.7±2.6%, pD2:6.32±0.098, n=3) and 2K‐1C rats (ME:101.1±0.4%, pD2:6.14 ±0.064, n=4). The pD2 was lower in RuBPY formulation than in RuBPY free, 2K (ME:112.7±34.6%, pD2:7.37±0.11, n=8) and 2K‐1C rats (ME:114.6±6.3%, pD2:7.19±0.12, n=5). RuBPY formulation is a potential vasodilator and this effect is similar in 2K and 2K‐1C rat aorta but it was less potent than RuBPY free. Supported by FAPESP and CNPq.