Disposition of Misoprostol and its Active Metabolite in Patients With Normal and Impaired Renal Function

The disposition of misoprostol acid, the active metabolite of misoprostol, was studied in 48 subjects with various degrees of renal function after administration of a single 400 μg oral dose of misoprostol. Subjects were assigned to one of four treatment groups: group 1, normal renal function with creatinine clearance (CL CR ) 80–140 mL/min/1.73 m 2 ; group 2, mild renal impairment with CL CR 50–79 mL/min/1.73 m 2 ; group 3, moderate renal impairment with CL CR 20–49 mL/min/1.73 m 2 or group 4, end stage renal disease (ESRD) patients maintained on hemodialysis. The maximum plasma concentration (C max ) and time to reach C max (t max ) for misoprostol acid tended to be larger in group 4 subjects; however, it failed to reach statistical significance. Although not statistically significant, in group 4 subjects the terminal half‐life (t 1/2 ) of misoprostol acid was almost twice as large (1.27 ± 0.77 h) as in groups 1, 2, and 3 (0.70 ± 0.72, 0.72 ± 0.67, and 0.73 ± 0.45 h, respectively). Misoprostol acid's total area under the plasma concentration curve (AUC 0 )∞ was larger in group 4 subjects (1173.5 ± 487.4 pg ∞ h/mL, as compared with groups 1, 2, and 3 (421.4 ± 263.1, 418.9 ± 114.5, and 377.0 ± 145.2 pg ∞ h/mL, respectively; P < .05). The apparent total body clearance (CL) of misoprostol acid was statistically significantly smaller in group 4 subjects (0.094 ± 0.044 L/kg/min) as compared only with group 3 subjects (0.284 ± 0.102 L/kg/min). The dose of misoprostol may need to be reduced in ESRD patients on prolonged hemodialysis to prevent unnecessary high plasma levels of misoprostol acid and to avoid possible dose‐related adverse effects .