Adempas

C₂₀H₁₉FN₈O₂

Riociguat is a white to yellowish, crystalline, non-hygroscopic substance with a molecular weight of 422.42 g/mol. In solid form it is stable to temperature, light, and humidity.

The solubility at 25°C in water: 4 mg/L, in ethanol: 800 mg/L, in 0.1 HCl (pH 1): 250 mg/L and in buffer (phosphate) pH 7: 3 mg/L. In the pH range of 2 to 4 the solubility showed strong pH-dependency. Solubility increases at lower pH values.

Each round film-coated tablet contains 0.5 mg (1.0, 1.5, 2.0, 2.5 mg) riociguat. The inactive ingredients are cellulose microcrystalline, crospovidone, hypromellose 5cP, lactose monohydrate, magnesium stearate, sodium laurylsulfate, hydroxypropylcellulose, hypromellose 3cP, propylene glycol, and titanium dioxide. Adempas 1, 1.5, 2 and 2.5 mg tablets contain, in addition, ferric oxide yellow. Adempas 2 and 2.5 mg tablets contain, in addition, ferric oxide red..

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action

Riociguat is a stimulator of soluble guanylate cyclase (sGC), an enzyme in the cardiopulmonary system and the receptor for nitric oxide (NO).

When NO binds to sGC, the enzyme catalyzes synthesis of the signaling molecule cyclic guanosine monophosphate (cGMP). Intracellular cGMP plays an important role in regulating processes that influence vascular tone, proliferation, fibrosis and inflammation.

Pulmonary hypertension is associated with endothelial dysfunction, impaired synthesis of nitric oxide and insufficient stimulation of the NO-sGC-cGMP pathway.

Riociguat has a dual mode of action. It sensitizes sGC to endogenous NO by stabilizing the NO-sGC binding. Riociguat also directly stimulates sGC via a different binding site, independently of NO.

Riociguat stimulates the NO-sGC-cGMP pathway and leads to increased generation of cGMP with subsequent vasodilation.

The active metabolite (M1) of riociguat is 1/3 to 1/10 as potent as riociguat.

12.2 Pharmacodynamics

There is a direct relationship between riociguat plasma concentration and hemodynamic parameters such as systemic vascular resistance, systolic blood pressure, pulmonary vascular resistance (PVR), and cardiac output [see Clinical Studies (14)].

Hemodynamic parameters were assessed in CTEPH patients in CHEST-1 [see Clinical Studies (14.1)]. Right heart catheterization was performed at the beginning and the end of the study period in 233 patients. A statistically significant reduction of PVR (-246 dyn*s*cm^-5) was shown in the Adempas group vs. placebo. Improvements in other hemodynamic parameters (not pre-specified as endpoints) are displayed in Table 2 below.

Hemodynamic parameters were assessed in PAH patients in PATENT-1 [see Clinical Studies (14.2)]. Right heart catheterization was performed at the beginning and the end of the study period in 339 patients.

A statistically significant reduction of PVR (-226 dyn*sec*cm^-5) was shown in the Adempas individual titration group (to maximum dose of 2.5 mg three times a day) vs. placebo. Improvement in other relevant hemodynamic parameters (not pre-specified as endpoints) for the individual dose titration group versus placebo are displayed in Table 3.

In the CHEST-1 study, Adempas significantly reduced N-terminal prohormone of brain natriuretic peptide (NT-proBNP), placebo-corrected mean change from baseline -444 ng/L, 95% CI -843 to -45. In the PATENT-1 study Adempas demonstrated a statistically significant reduction of NT-proBNP, placebo‑corrected mean change from baseline: -432 ng/L, 95% CI –782 to –82.

Nitrates: Riociguat 2.5 mg tablets potentiated the blood pressure lowering effect of sublingual nitroglycerin (0.4 mg) taken 4 and 8 hours after riociguat. Syncope was reported in some patients [see Contraindications (4.2)].

Phosphodiesterase-5 inhibitors: In an exploratory interaction study in 7 patients with PAH on stable sildenafil treatment (20 mg three times a day), single doses of riociguat (0.5 mg and 1 mg sequentially) showed additive hemodynamic effects.

Among patients with PAH on stable sildenafil treatment (20 mg, three times a day) and riociguat (1 to 2.5 mg, three times a day) there was one death, possibly related to the combination of these drugs, and a high rate of discontinuation for hypotension [see Contraindications (4.3)].

Warfarin: Concomitant administration of riociguat and warfarin did not alter prothrombin time.

Acetylsalicylic Acid: Concomitant use of riociguat and aspirin did not affect bleeding time or platelet aggregation

12.3 Pharmacokinetics

Riociguat pharmacokinetics are dose proportional from 0.5 to 2.5 mg. Inter-individual variability of riociguat exposure (AUC) across all doses is approximately 60%, and within-subject variability is approximately 30%.

The absolute bioavailability of riociguat is about 94%. Peak plasma riociguat concentrations were observed within 1.5 hours after tablet intake. Food does not affect the bioavailability of riociguat.

The volume of distribution at steady state is approximately 30 L. Plasma protein binding in humans is approximately 95%, with serum albumin and α1–acidic glycoprotein being the main binding components.

Riociguat is a substrate of P-gp and BCRP.

Riociguat is mainly cleared by metabolism by CYP1A1, CYP3A, CYP2C8 and CYP2J2. Formation of the major active metabolite, M1, is catalyzed by CYP1A1, which is inducible by polycyclic aromatic hydrocarbons such as those present in cigarette smoke. M1 is further metabolized to the inactive N-glucuronide. Plasma concentrations of M1 in patients with PAH are about half those for riociguat.

Following oral administration of radiolabeled riociguat in healthy individuals, about 40 and 53% of the total radioactivity was recovered in urine and feces, respectively. There appears to be considerable variability in the proportion of metabolites and unchanged riociguat excreted, but metabolites were the major components of the dose excreted in most individuals.

Average systemic clearance of riociguat was about 1.8 L/h in patients with PAH and about 3.4 L/h in healthy subjects. The terminal elimination half-life is about 12 hours in patients and 7 hours in healthy subjects.

Specific Populations: The effect of intrinsic factors on riociguat and M1 are shown below in Figure 1. There are no clinically relevant effects of age, sex, weight, or race/ethnicity on the pharmacokinetics of riociguat or M1. No dose adjustment is warranted.

Drug interactions: The effect of other extrinsic factors on riociguat and M1 were studied in healthy subjects and are shown in Figure 2

*HIV protease inhibitors are strong CYP3A inhibitors and may increase riociguat plasma concentrations to levels similar to those seen with ketoconazole. ** AUC only, estimated using population pharmacokinetics methods *** AUC only for metabolite, estimated using population pharmacokinetics methods. **** Monitor for signs and symptoms of hypotension on initiation and on treatment with strong CYP and P-gp/BCRP inhibitors [see Dosage and Administration (2.4, 2.5), Warnings and Precautions (5.3) and Drug Interactions (7.2)].

Strong CYP3A inducers: Data are not available to inform dosing of riociguat when strong CYP3A inducers are co-administered [see Drug Interactions (7.2)].

Effects of Riociguat on other Drugs: Riociguat did not affect the pharmacokinetics of midazolam, warfarin, or sildenafil [see Contraindications (4.3) and Clinical Pharmacology (12.2)].

13 NONCLINICAL TOXICOLOGY

13.1 Carcinogenesis, Mutagenesis, Impairment of Fertility

Carcinogenesis: Carcinogenicity studies of riociguat were conducted in mice and rats. In mice, oral administration of riociguat (up to 25 mg/kg/day in males and 32 mg/kg/day in females) for up to two years did not demonstrate evidence of carcinogenesis. Plasma exposure (AUC) of unbound riociguat at the highest dose was 6 times the human’s exposure.

In rats, oral administration of riociguat (up to 20 mg/kg/day) for up to two years did not demonstrate evidence of carcinogenesis. Plasma exposure (AUC) of unbound riociguat at the highest dose was 7 times the human exposure

Mutagenesis: Riociguat and M1 did not show genotoxic potential in the in vitro bacterial reverse mutation (Ames) assay, the in vitro chromosomal aberration assay in Chinese hamster V79 cells, or the in vivo micronucleus assay in the mouse.

Impairment of fertility: In rats, no effects on male or female fertility were observed.

In male rats, oral administration of riociguat (up to 30 mg/kg/day) prior to and throughout the mating period had no effect on fertility. The no-effect dose for adverse effects is 37 times the human exposure when based on body surface area.

In female rats, oral administration of riociguat (up to 30 mg/kg/day) prior to and during mating and continuing to gestation Day 7 had no effect on fertility. The no-effect dose for adverse effects is 37 times the human exposure when based on body surface area.

13.2 Animal Toxicology

In growing rats, effects on bone formation were observed, including thickening of the growth plates, disorganized trabecular bone, and diffuse hyperostosis [see Use in Specific Populations (8.4)].

14 CLINICAL STUDIES

14.1 Chronic-Thromboembolic Pulmonary Hypertension

A double-blind, multi-national, multi-center, study (CHEST-1) was conducted in 261 patients with CTEPH. Patients were included if they:

• •were technically inoperable for pulmonary endarterectomy, with PVR >300 dyn*sec*cm^-5 and mean pulmonary artery pressure >25 mmHg measured at least 90 days after the start of full anticoagulation, or
• •had recurrent or persisting pulmonary hypertension defined as PVR > 300 dyn*sec*cm^-5 measured at least 180 days following pulmonary endarterectomy.

Patients were randomized to Adempas titrated up to 2.5 mg three times a day (n=173) or placebo (n=88). All patients were initiated at 1 mg three times a day. Patients with systolic blood pressure < 95 mmHg were excluded from the study. The dose of riociguat was titrated every 2 weeks based on the patient’s systolic blood pressure and signs or symptoms of hypotension. Stable dosages of oral anticoagulants, diuretics, digitalis, calcium channel blockers and oxygen were allowed, but not concomitant therapy with NO donors, endothelin receptor antagonists, prostacyclin analogues (PCA), specific PDE-5 inhibitors (such as, sildenafil, tadalafil, or vardenafil), and nonspecific phosphodiesterase inhibitors (for example, dipyridamole or theophylline).

The primary endpoint of the study was change from baseline in six minute walking distance (6MWD) after 16 weeks. The mean age of the patients enrolled was 59 years (range 18–80 years). In the study, 72% of patients had inoperable CTEPH, 28% had recurrent or persisting pulmonary hypertension following pulmonary endarterectomy. The majority of patients had a World Health Organization (WHO) Functional Class II (31%) or III (64%) at baseline. The mean baseline 6MWD was 347 meters. In the study, 77% of patients were titrated to the maximum dose of 2.5 mg three times a day; 13%, 6%, 4%, and 1% of patients were titrated to riociguat doses of 2, 1.5, 1, and 0.5 mg three times a day, respectively.

Results of the 6MWD over 16 weeks for the CHEST-1 study are shown in Figure 3.

The pre-specified primary endpoint of the study was the change in 6MWD from baseline to week 16 and was based on imputed values. The imputation for missing values included last observed value, not including follow-up for patients who completed the study or withdrew. For deaths or clinical worsening without a termination visit or a measurement at that visit, the imputed worst value (zero) was used.

Improvements in walking distance were apparent from Week 2 onward. At Week 16, the placebo adjusted mean increase in 6MWD within the Adempas group was 46 m (95% confidence interval [CI]: 25 m to 67 m; p<0.0001). For CHEST-1, the median difference (Hodges-Lehmann non-parametric estimate) in 6MWD was 39 m (95% CI, 25 m to 54 m).

Figure 4 illustrates the results of the Adempas and placebo treatment groups displayed as a histogram summarizing the treatment effect on the 6MWD. The patients are grouped by change in 20 meters from baseline. Overall this figure shows that patients treated with Adempas benefit compared to those treated with placebo. As demonstrated in Figure 4, 143 patients receiving Adempas (83%) experienced an improvement in 6MWD compared to 50 patients (57%) on placebo.

Placebo-adjusted changes in 6MWD at 16 weeks were evaluated in subgroups (see Figure 5).

WHO Functional Class improvements in the CHEST-1 trial are shown in Table 4.

An open-label extension study (CHEST-2) included 237 patients who had completed CHEST-1. At the cut-off date in the CHEST-2 study, the mean treatment duration for the total population was 582 days (± 317). The probability of survival at 1 year and 2 years were 97% and 94%, respectively. Additionally, 6MWD and WHO Functional Class status appeared to further improve in patients taking Adempas. Without a control group, however, these data must be interpreted cautiously.

14.2 Pulmonary Arterial Hypertension

A double-blind, multi-national, multi-center study (PATENT-1) was conducted in 443 patients with PAH as defined by PVR >300 dyn*sec*cm^-5 and a PAP _mean >25 mmHg.

Patients were randomized to one of three treatment groups: Adempas titrated up to 1.5 mg (n=63), 2.5 mg (n=254) or placebo (n=126) three times a day. Patients with systolic blood pressure < 95 mmHg were excluded from the study. Patients assigned to Adempas were initiated at 1.0 mg three times a day. The dose of Adempas was up-titrated every 2 weeks based on the patient’s systolic blood pressure and signs or symptoms of hypotension. Oral anticoagulants, diuretics, digitalis, calcium channel blockers, and oxygen were allowed. In this study, 50% of the patients were treatment-naive with respect to PAH therapy, 44% were pre-treated with an endothelin receptor antagonist (ERA) and 6% were pre-treated with a PCA (inhaled, oral or subcutaneous). Pre-treated patients were defined as patients on stable treatment for 3 months with either an ERA or PCA; Adempas was added in combination to these background therapies.

The primary endpoint of the study was change from baseline and placebo in 6MWD after 12 weeks in the 2.5 mg group. The mean age of all patients was 51 years and approximately 80% were female. PAH etiologies were either idiopathic (61%) or familial PAH (2%), PAH associated with connective tissue disease (25%), congenital heart disease (8%), portal hypertension (3%), or anorexigen or amphetamine use (1%). The majority of patients had a WHO Functional Class II (42%) or III (54%) at baseline. The overall mean baseline 6MWD was 363 meters. Approximately 75% of patients were up-titrated to receive the maximum dose of 2.5 mg three times a day by week 12; 15%, 6%, 3%, and 2% were titrated to doses of 2 mg, 1.5 mg, 1 mg, and 0.5 mg 3 times a day, respectively.

Results of the 6MWD over 12 weeks for the PATENT-1 study are shown in Figure 6.

The pre-specified primary endpoint of the study was the change in 6MWD from baseline to week 12 and was based on imputed values. The imputation for missing values included last observed value, not including follow-up for patients who completed the study or withdrew. In case of death or clinical worsening without a termination visit or a measurement at that termination visit, the imputed worst value (zero) was used.

Figure 7 illustrates the results of the Adempas and placebo treatment groups displayed as a histogram summarizing the treatment effect on the 6MWD. The patients are grouped by change in 20 meters from baseline. Overall this figure shows that patients treated with Adempas benefit compared to those treated with placebo. As demonstrated in Figure 7, 193 patients receiving Adempas (76%) experienced an improvement in 6MWD compared to 74 patients (59%) on placebo.

Improvements 6MWD were apparent from Week 2 onward. At Week 12, the placebo-adjusted mean increase in 6MWD within the Adempas group was 36 m (95% CI: 20 m to 52 m; p<0.0001). For PATENT-1, the median difference (Hodges-Lehmann non-parametric estimate) in 6MWD was 29 m (95% CI, 17 m to 40 m).There was an exploratory 1.5 mg capped titration arm (n = 63). The data did not suggest incremental benefit from escalating dose from 1.5 mg three times a day to 2.5 mg three times a day.

Placebo-adjusted changes in 6MWD at 12 weeks were evaluated in subgroups (see Figure 8).

WHO Functional Class improvements in the IDT (individual dose titration) arm of the PATENT-1 trial are shown in Table 5

Time to clinical worsening was a combined endpoint defined as death (all-cause mortality), heart/lung transplantation, atrial septostomy, hospitalization due to persistent worsening of pulmonary hypertension, start of new PAH-specific treatment, persistent decrease in 6MWD and persistent worsening of WHO Functional Class.

Effects of Adempas in PATENT-1 on events of clinical worsening are shown in Table 6.

* p-value=0.0285 (Mantel-Haenszel estimate)

Note: Patients may have had more than one event of clinical worsening

Adempas-treated patients experienced a significant delay in time to clinical worsening versus placebo-treated patients (p=0.0046; Stratified log-rank test). Significantly fewer events of clinical worsening up to week 12 (last visit) were observed in patients treated with Adempas (1.2%) compared to placebo (6.3%) (p=0.0285, Mantel-Haenszel estimate).

The Kaplan-Meier plot of time to clinical worsening is presented in Figure 9.

An open label extension study (PATENT-2) included 363 patients who had completed PATENT-1. At the cut-off date in the PATENT-2 study, the mean treatment duration for the total population was 663 days (± 319). The probabilities of survival at 1 and 2 years were 97% and 93%, respectively. Without a control group, these data must be interpreted cautiously.

16 HOW SUPPLIED/STORAGE AND HANDLING

16.1 How Supplied

Adempas (riociguat) tablets are film-coated, round, and debossed with the “Bayer cross” on one side.

16.2 Storage

Store at 25°C (77°F); excursions are permitted from 15°C to 30°C (59°F to 86°F) [see USP Controlled Room Temperature].

17 PATIENT COUNSELING INFORMATION

See FDA-approved patient labeling (Medication Guide).

Embryo-Fetal Toxicity

Instruct patients on the risk of fetal harm when Adempas is used during pregnancy [see Warnings and Precautions (5.1) and Use in Specific Populations (8.1)]. Instruct females of reproductive potential to use effective contraception and to contact her physician immediately if they suspect they may be pregnant. Female patients must enroll in the Adempas REMS Program.

Adempas REMS Program

For female patients, Adempas is available only through a restricted program called the Adempas REMS Program [see Warnings and Precautions (5.2)]. Male patients are not enrolled in the Adempas REMS Program.

Inform female patients (and their guardians, if applicable) of the following important requirements:

• •All female patients must sign an enrollment form.
• •Advise female patients of reproductive potential that she must comply with the pregnancy testing and contraception requirements [see Use in Specific Populations (8.6)].
• •Educate and counsel females of reproductive potential on the use of emergency contraception in the event of unprotected sex or contraceptive failure.
• •Advise pre-pubertal females to report any changes in their reproductive status immediately to her prescriber.

Review the Medication Guide and REMS educational materials with female patients.

Other Risks Associated with Adempas

• •Inform patients of the contraindication of Adempas with nitrates or nitric oxide donors or PDE-5 inhibitors.
• •Advise patients about the potential risks/signs of hemoptysis and to report any potential signs of hemoptysis to their physicians.
• •Instruct patients on the dosing, titration, and maintenance of Adempas.
• •Advise patients regarding activities that may impact the pharmacology of Adempas (strong multi pathway CYP inhibitors and P-gp/BCRP inhibitors and smoking). Patients should report all current medications and new medications to their physician.
• •Advise patients that antacids should not be taken within 1 hour of taking Adempas.
• •Inform patients that Adempas can cause dizziness, which can affect the ability to drive and use machines [see Adverse Reactions (6.1)]. They should be aware of how they react to Adempas, before driving or operating machinery and if needed, consult their physician.

MEDICATION GUIDE

Adempas (a dem pahs)
(riociguat)

tablets

Read this Medication Guide before you start taking Adempas and each time you get a refill. There may be new information. This Medication Guide does not take the place of talking to your doctor about your medical condition or your treatment.

What is the most important information I should know about Adempas?

• • Serious birth defects.
• • Adempas can cause serious birth defects if taken during pregnancy.
• • Females must not be pregnant when they start taking Adempas or become pregnant during treatment with Adempas.
• •Females who are able to get pregnant must have a negative pregnancy test before beginning treatment with Adempas, each month during treatment, and 1 month after you stop treatment with Adempas. Talk to your doctor about your menstrual cycle. Your doctor will decide when to do the tests, and order the tests for you depending on your menstrual cycle.
  • •Females who are able to get pregnant are females who:
• •Have entered puberty, even if they have not started their period, and
• •Have a uterus, and
  • •Have not gone through menopause (have not had a period for at least 12 months for natural reasons, or who have had their ovaries removed)
  • •Females who are not able to get pregnant are females who:
  • •Have not yet entered puberty, or
  • •Do not have a uterus, or
  • •Have gone through menopause (have not had a period for at least 12 months for natural reasons, or who have had their ovaries removed)

Females who are able to get pregnant must use two acceptable forms of birth control, during treatment with Adempas and for one month after stopping Adempas because the medicine may still be in the body.

• •If you have had a tubal sterilization, have a progesterone implant, or have an IUD (intrauterine device), these methods can be used alone and no other form of birth control is needed.
  • •Talk with your doctor or gynecologist (a doctor who specializes in female reproduction) to find out about options for acceptable birth control that you may use to prevent pregnancy during treatment with Adempas.
• •If you decide that you want to change the form of birth control that you use, talk with your doctor or gynecologist to be sure that you choose another acceptable form of birth control.

See the chart below for Acceptable Birth Control Options during treatment with Adempas.