Pharmacokinetics of the soluble guanylate cyclase stimulator riociguat in individuals with renal impairment

Population pharmacokinetics of single-dose riociguat in patients with renal or hepatic impairment

This population pharmacokinetics (PK) analysis characterized the PK of the oral soluble guanylate cyclase stimulator riociguat in patients with renal or hepatic impairment and determined whether smoking affects riociguat dosing. Two phase 1 studies were performed in patients with renal impairment (n = 72, of whom 11 were smokers), and two were performed in those with hepatic impairment (n = 64, of whom 12 were smokers). Plasma and urine samples were collected after a single oral dose of riociguat 1.0 or 0.5 mg. Nonlinear mixed-effects modeling was used to develop a combined, two-compartment population PK model for riociguat and its main metabolite, M1. Riociguat and M1 clearance was split into renal and nonrenal parts; the nonrenal part for riociguat was divided into metabolism to M1 and a metabolic (nonrenal) part. Total clearance of riociguat was 1.912 L/h. The main route of riociguat clearance is metabolism to M1 (1.2 L/h). In this model, hepatic function biomarkers or Child-Pugh classification had no significant effect on riociguat or M1 clearance. Nonrenal (nonmetabolism) riociguat clearance was similar in all groups. Renal clearance (0.242 L/h) contributed less to riociguat total clearance, mainly determined by glomerular filtration (0.174 L/h). Renal impairment reduced riociguat and M1 clearance. Hepatic or renal impairment had limited effects on total exposure to riociguat. However, individual dose adjustment of riociguat should be administered with particular care in patients with moderate hepatic or renal impairment. Riociguat is not recommended in severe hepatic or renal impairment. Smoking reduced riociguat exposure by significantly increasing metabolism to M1.

Assessment of the effects of renal impairment and smoking on the pharmacokinetics of a single oral dose of the soluble guanylate cyclase stimulator riociguat (BAY 63-2521)

Renal impairment is a common comborbidity in patients with pulmonary hypertension. The breakdown of riociguat, an oral soluble guanylate cyclase stimulator used to treat pulmonary hypertension, may be affected by smoking because polycyclic aromatic hydrocarbons in tobacco smoke induce expression of one of the metabolizing enzymes, CYP1A1. Two nonrandomized, nonblinded studies were therefore performed to investigate the pharmacokinetics and safety of a single oral dose of riociguat 1.0 mg in individuals with mild, moderate, or severe renal impairment compared with age-, weight-, and sex-matched healthy controls, including either smokers and nonsmokers (study I) or nonsmokers alone (study II). Pharmacokinetic analyses focused on the integrated per-protocol data set of both studies (N = 63). In patients with renal impairment, the renal clearance of riociguat was reduced and its terminal half-life prolonged compared with those in healthy controls. There was a monotonic relationship between creatinine clearance on treatment day and riociguat renal clearance (R (2) = 0.62). However, increased riociguat exposure with decreasing renal function was not strictly proportional. Riociguat exposure appeared to be greater in nonsmokers than in the combined population of smokers and nonsmokers, irrespective of renal function. Adverse events were mild to moderate and in line with the mode of action of riociguat. No serious adverse events occurred. In conclusion, renal impairment was associated with reduced riociguat clearance compared with that in controls; however, riociguat exposure in patients with renal impairment was highly variable, and ranges overlapped with those observed in healthy controls.

Assessment of the effects of hepatic impairment and smoking on the pharmacokinetics of a single oral dose of the soluble guanylate cyclase stimulator riociguat (BAY 63-2521)

Riociguat, a soluble guanylate cyclase stimulator developed for the treatment of pulmonary hypertension, is metabolized in part by the liver. Expression of one of the metabolizing enzymes, CYP1A1, is induced by aromatic hydrocarbons in tobacco smoke. Two nonrandomized, nonblinded studies were conducted to investigate the pharmacokinetics of riociguat in individuals with mild (Child-Pugh A) or moderate (Child-Pugh B) hepatic impairment associated with liver cirrhosis compared with that in age-, weight-, and sex-matched healthy controls: study 1 included smokers and nonsmokers, and study 2 included nonsmokers only. Data from these studies were integrated for analysis. All participants (N = 64) received a single oral dose of riociguat 1.0 mg. Riociguat exposure was significantly higher in individuals with Child-Pugh B hepatic impairment than in healthy controls (ratio: 153% [90% confidence interval: 103%-228%]) but was similar in those with Child-Pugh A hepatic impairment and controls. The half-life of the riociguat metabolite M1 was prolonged in patients with Child-Pugh B or A hepatic impairment compared with that in controls by approximately 43% and 24%, respectively. Impaired hepatic function was associated with higher riociguat exposure in nonsmokers compared with the population of smokers and nonsmokers combined. Riociguat's safety profile was similar in individuals with impaired or normal liver function. In conclusion, moderate hepatic impairment was associated with increased riociguat exposure compared with that in controls, probably as a result of reduced clearance of the metabolite M1. This suggests that dose titration of riociguat should be administered with particular care in patients with moderate hepatic impairment.