Adempas Tablets

Pregnancy

Risk Summary

Adempas may cause fetal harm when administered to a pregnant woman and is contraindicated during pregnancy. Adempas was teratogenic and embryotoxic in rats at doses with exposures to unbound drug that were approximately 8 times and 2 times, respectively, the human exposure. In rabbits, riociguat led to abortions at 4 times the human exposure and fetal toxicity with exposures approximately 13 times the human exposure. If Adempas is used in pregnancy, or if the patient becomes pregnant while taking this drug, apprise the patient of the potential hazard to the fetus [see Boxed Warning and Contraindications (4.1)].

Animal Data

In rats administered riociguat orally (1, 5, and 25 mg/kg/day) throughout organogenesis, an increased rate of cardiac ventricular-septal defect was observed at the highest dose tested. The highest dose produced evidence of maternal toxicity (reduced body weight). Post-implantation loss was statistically significantly increased from the mid-dose of 5 mg/kg/day. Plasma exposure at the lowest dose in which no adverse effects were observed is approximately 0.4 times that in humans at the maximally recommended human dose (MRHD) of 2.5 mg three times a day based on area under the time-concentration curve (AUC) for unbound drug in rat and humans. Plasma exposure at the highest dose (25 mg/kg/day) is approximately 8 times that in humans at the MRHD while exposure at the mid-dose (5 mg/kg/day) is approximately 2 times that in humans at the MRHD. In rabbits given doses of 0.5, 1.5 and 5 mg/kg/day, an increase in spontaneous abortions was observed starting at the middle dose of 1.5 mg/kg, and an increase in resorptions was observed at 5 mg/kg/day. Plasma exposures at these doses were 4 times and 13 times, respectively, the human exposure at the MRHD.

Nursing Mothers

It is not known if Adempas is present in human milk. Riociguat or its metabolites were present in the milk of rats. Because many drugs are present in human milk and because of the potential for serious adverse reactions in nursing infants from riociguat, discontinue nursing or Adempas.

Pediatric Use

Safety and effectiveness of Adempas in pediatric patients have not been established [see Nonclinical Toxicology (13.2)].

Geriatric Use

Of the total number of subjects in clinical studies of Adempas, 23% were 65 and over, and 6% were 75 and over [see Clinical Studies (14)]. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.

Elderly patients showed a higher exposure to Adempas [see Clinical Pharmacology (12.3)].

Females and Males of Reproductive Potential

Pregnancy Testing: Female patients of reproductive potential must have a negative pregnancy test prior to starting treatment with Adempas, monthly during treatment, and one month after discontinuation of treatment with Adempas. Advise patients to contact their healthcare provider if they become pregnant or suspect they may be pregnant. Counsel patients on the risk to the fetus [see Boxed Warning, Dosage and Administration (2.3) and Use in Specific Populations (8.1)].

Contraception: Female patients of reproductive potential must use acceptable methods of contraception during treatment with Adempas and for 1 month after treatment with Adempas. Patients may choose one highly effective form of contraception (intrauterine devices [IUD], contraceptive implants or tubal sterilization) or a combination of methods (hormone method with a barrier method or two barrier methods). If a partner’s vasectomy is the chosen method of contraception, a hormone or barrier method must be used along with this method. Counsel patients on pregnancy planning and prevention, including emergency contraception, or designate counseling by another healthcare provider trained in contraceptive counseling [see Boxed Warning].

Renal Impairment

Safety and efficacy have not been demonstrated in patients with creatinine clearance <15 mL/min or on dialysis [see Clinical Pharmacology (12.3)].

Hepatic Impairment

Safety and efficacy have not been demonstrated in patients with severe hepatic impairment (Child Pugh C) [see Clinical Pharmacology (12.3)].

Adempas (riociguat) is a tablet for oral administration. Riociguat is methyl 4,6-diamino-2-[1-(2-fluorobenzyl)-1H-pyrazolo [3,4-b]pyridin-3-yl]-5-pyrimidinyl(methyl)carbamate with the following structural formula:

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..

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.

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.

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.

Bioavailability (AUC and Cmax) of riociguat administered orally as a crushed tablet suspended in applesauce or in water is similar to that of a whole tablet.

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 through metabolism by CYP1A1, CYP3A4, CYP3A5, 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.

Figure 1: Effect of Intrinsic Factors on Riociguat and M1 Pharmacokinetics

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

Figure 2: Effect of Extrinsic Factors on Riociguat and M1 Pharmacokinetics

*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)].

Riociguat (2.5 mg three times per day) did not affect the systemic exposure of combined oral contraceptives containing levonorgestrel and ethinyl estradiol when concomitantly administered to healthy female subjects.

NDC 50419-250-01
Rx only
Adempas 0.5 mg
(riociguat) tablets
each tablet contains 0.5 mg of riociguat

Note to Dispencer: Provide a copy of the Adempas Medication Guide included in this carton to each patient and at each refill.

- 90 tablets
- for oral administration

Applies to riociguat: oral tablet

Along with its needed effects, riociguat may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking riociguat:

• Confusion
• dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
• nosebleeds
• unusual tiredness or weakness

• Abdominal or stomach pain or swelling
• bloating or swelling of the face, arms, hands, lower legs, or feet
• bloody or black, tarry stools
• bruising or purple areas on the skin
• coughing or spitting up blood
• decreased alertness
• fast, irregular, pounding, or racing heartbeat or pulse
• heavy non-menstrual vaginal bleeding
• rapid weight gain
• troubled breathing with exertion
• vomiting of blood or material that looks like coffee grounds

Some side effects of riociguat may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

• Diarrhea
• headache
• heartburn or indigestion
• nausea or vomiting
• stuffy nose

• Difficulty having a bowel movement (stool)

Applies to riociguat: oral tablet

General

The most frequently reported side effects were headache, dyspepsia/gastritis, dizziness, nausea, diarrhea, hypotension, vomiting, anemia, gastroesophageal reflux, and constipation.[Ref]

Cardiovascular

Very common (10% or more): Peripheral edema (up to 17.3%), hypotension (up to 10%)
Common (1% to 10%): Palpitation, chest pain, chest discomfort[Ref]

Nervous system

Very common (10% or more): Headache (up to 27%), dizziness (up to 20%)[Ref]

Gastrointestinal

Very common (10% or more): Dyspepsia (up to 21%), gastritis (21%), nausea (up to 14.1%), diarrhea (up to 12%), vomiting (up to 10.2%)
Common (1% to 10%): Gastroesophageal reflux disease, constipation, gastroenteritis, gastrointestinal/abdominal pain, dysphagia, abdominal distention[Ref]

Hematologic

Very common (10% or more): Hemoglobin decreased (24.1%), hematocrit decreased (13.3%)
Common (1% to 10%): Anemia[Ref]

Respiratory

Very common (10% or more): Nasopharyngitis (11.8%)
Common (1% to 10%): Dyspnea, cough, nasal congestion, epistaxis, hemoptysis
Frequency not reported: Pulmonary hemorrhage[Ref]

Musculoskeletal

Common (1% to 10%): Pain in extremity[Ref]

Other

Common (1% to 10%): Fatigue[Ref]

Some side effects of riociguat may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.