[6] Efficacy: In the PATENT-1 trial, the overall difference in the 6MWD with riociguat as compared with placebo, was 36 m at 12 weeks. This change in 6MWD is consistent with the increases compound library on 96 well plate observed in previous studies (22.4 m; 95% confidence interval: 17.4–27.5 m). 17 In comparison with PDE-5 inhibitors, this change in 6MWD is less than that observed with sildenafil in the SUPER trial, 18 where the mean placebo-corrected treatment on 6MWD was 45 m, 46 m, and

50 m for patients receiving 20, 40, and 80 mg of sildenafil, respectively. On the other hand, the improvement in 6MWD reported in PATENT-1 is close to that reported with tadalafil in the PHIRST trial, where tadalafil in 40 mg was associated with 33 m increase in 6MWD relative to placebo. 19 Improvement

in WHO functional class in PATENT-1 is modest where 21% of patients moved to lower class. In SUPER trial, the proportions of patients with an improvement of at least one functional class were 7%, 36%, and 42% for patients receiving 20, 40, and 80 mg of sildenafil, respectively. 18 In the PHIRST trial, no significant differences in the proportions of patients with and without improvement of WHO functional class were observed with tadalafil compared with placebo. 19 Importantly, many variables should be considered when comparing changes in 6MWD or WHO functional class among different studies (e.g., population characteristics, baseline 6MWD and WHO functional class, duration of study, proportion of patients on background therapy). For example, in the PHIRST study, 19 about half of patients were receiving bosentan as a background therapy, while in SUPER background therapy was not

permitted. 18 This is important since the use of background effective therapy may reduce the ability to demonstrate a statistically significant difference in 6MWD or WHO functional class between the placebo and the active treatment groups. [7] Safety: Riociguat was well tolerated and had a favorable safety profile. Batimastat Two adverse events appear to be common among patients receiving the highest tolerated dose of riociguat: hypotension (10%) and anemia (8%). 6 The risk of hypotension should be minimized by a gradual individual dose titration to the highest tolerated dose (in PATENT-1, riociguat was titrated over 8 weeks), and by contraindicating concomitant use with other drugs affecting the NO-sGC-cGMP pathway (e.g., PDE-5 inhibitors, nitrates). The apparent increased risk of bleeding has been addressed by means of a prominent warning and a description of bleeding events in the adverse reactions section of the Product Monograph. [8] Drug-drug interaction: So far, the interaction potential of riociguat with other drugs is virtually unknown.