Figure 7.

Effect of eplerenone and PF-03882845 on urinary Na⁺/K⁺ ratio. SD rats received single doses of 0, 5, 30, or 3.0 mg/kg eplerenone or 0, 3, 10, or 30 mg/kg PF-03882845 and urinary Na⁺/K⁺ was assessed at 0–2, 2–4, and 4–7 h post-dose. Both compounds yielded analogous concentration-effect curves for urinary Na⁺/K⁺. Data were expressed as free concentration normalized to in vitro IC50 (0.75 nM for PF-03882845 and 109 nM for eplerenone in a serum free assay). Data were modeled using an indirect response model. Dashed lines indicate the 95% lower and upper confidence boundary limits.