PAH is a severe, progressive disease

Pulmonary arterial hypertension (PAH) results from restricted flow through the pulmonary arteries, leading to increased pulmonary vascular resistance (PVR) and, ultimately, right heart failure and death.1

Hemodynamic trends in pulmonary arterial pressure (PAP), PVR, and cardiac output (CO) correlate with increasing disease severity.2 Early in the disease, PVR and PAP may be elevated, but due in part to right ventricular (RV) compensation, CO remains within normal range for an indeterminate time. Patients may not be diagnosed until they present with overt symptoms such as dyspnea, fatigue, and edema in the lower extremities.3

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PAH is associated with diverse pathologic events

Pulmonary vasoconstriction

The pulmonary arteries contract, and vascular resistance increases.2,3

Right ventricular strain and dysfunction

Chronic elevated pressures lead to right ventricular strain and overload.2,4

Fibrosis

Over time, the vascular intima thickens, further impeding blood flow.4

Hypertrophy

Vascular hypertrophy occurs in the presence of developing lesions and other arterial abnormalities.4,5

In situ thrombosis

Abnormalities in platelet activation and function promote thrombosis and can lead to increased vasoconstriction.5

A system out of balance

Endothelial dysfunction results in overproduction of vasoconstrictors such as endothelin-1 (ET-1) and underproduction of vasodilators such as nitric oxide and prostacyclin.3,4

ET-1 and its receptors (ETA and ETB) mediate a variety of deleterious effects such as vasoconstriction, fibrosis, proliferation, hypertrophy, and inflammation.6

OPSUMIT® (macitentan) acts on the endothelin pathway, 1 of 3 principal pathways in PAH.6,7

Because 3 separate signaling pathways are involved in PAH, the use of combination therapy as initial or sequential therapy is a common treatment strategy.1

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PDE-5=phosphodiesterase type 5; sGCs=soluble guanylate cyclase stimulator.
References: 1. Galiè N, Humbert M, Vachiery J-L, et al. 2015 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension: The Joint Task Force for the Diagnosis and Treatment of Pulmonary Hypertension of the European Society of Cardiology (ESC) and the European Respiratory Society (ERS). Eur Respir J. 2015;46(4):903-975. 2. Howard LS. Prognostic factors in pulmonary arterial hypertension: assessing the course of the disease. Eur Respir Rev. 2011;20(122):236-242. 3. Minai OA, Budev MM. Diagnostic strategies for suspected pulmonary arterial hypertension: a primer for the internist. Cleve Clin J Med. 2007;74:737-747. 4. McLaughlin VV, Archer SL, Badesch DB, et al. ACCF/AHA 2009 expert consensus document on pulmonary hypertension. J Am Coll Cardiol. 2009;53(17):1573-1619. 5. Blaise G, Langleben D, Hubert B. Pulmonary arterial hypertension: pathophysiology and anesthetic approach. Anesthesiology. 2003;99(6):1415-1432. 6. Rich S. Pulmonary hypertension. In: Bonow RO, Mann DL, Zipes DE, Libby P, eds. Braunwald’s Heart Disease. A Textbook of Cardiovascular Disease. Vol 2. 9th ed. Philadelphia, PA: Saunders Elsevier; 2012:1696-1718. 7. OPSUMIT [prescribing information]. South San Francisco, CA: Actelion Pharmaceuticals US, Inc.

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IMPORTANT SAFETY INFORMATION

BOXED WARNING: EMBRYO-FETAL TOXICITY

  • Do not administer OPSUMIT to a pregnant female because it may cause fetal harm.
  • Females of reproductive potential: Exclude pregnancy before the start of treatment, monthly during treatment, and 1 month after stopping treatment. Prevent pregnancy during treatment and for one month after stopping treatment by using acceptable methods of contraception.
  • For all female patients, OPSUMIT is available only through a restricted program called the OPSUMIT Risk Evaluation and Mitigation Strategy (REMS).

INDICATION

OPSUMIT is an endothelin receptor antagonist (ERA) indicated for the treatment of pulmonary arterial hypertension (PAH, WHO Group I) to reduce the risks of disease progression and hospitalization for PAH.

Effectiveness was established in a long-term study in PAH patients with predominantly WHO Functional Class II-III symptoms treated for an average of 2 years. Patients had idiopathic and heritable PAH (57%), PAH caused by connective tissue disorders (31%), and PAH caused by congenital heart disease with repaired shunts (8%).

CONTRAINDICATIONS

Pregnancy: OPSUMIT may cause fetal harm when administered to a pregnant woman. OPSUMIT is contraindicated in females who are pregnant. If OPSUMIT is used during pregnancy, advise the patient of the potential risk to a fetus.

WARNINGS AND PRECAUTIONS

Embryo-fetal Toxicity and OPSUMIT REMS Program

Due to the risk of embryo-fetal toxicity, OPSUMIT is available for females only through a restricted program called the OPSUMIT REMS Program. For females of reproductive potential, exclude pregnancy prior to initiation of therapy, ensure use of acceptable contraceptive methods, and obtain monthly pregnancy tests.

Notable requirements of the OPSUMIT REMS Program include:

  • Prescribers must be certified with the program by enrolling and completing training.
  • All females, regardless of reproductive potential, must enroll in the OPSUMIT REMS Program prior to initiating OPSUMIT. Male patients are not enrolled in the REMS.
  • Females of reproductive potential must comply with the pregnancy testing and contraception requirements.
  • Pharmacies must be certified with the program and must only dispense to patients who are authorized to receive OPSUMIT.

Hepatotoxicity

  • ERAs have caused elevations of aminotransferases, hepatotoxicity, and liver failure. The incidence of elevated aminotransferases in the SERAPHIN study >3 x ULN was 3.4% for OPSUMIT vs 4.5% for placebo, and >8 x ULN was 2.1% vs 0.4%, respectively. Discontinuations for hepatic adverse events were 3.3% for OPSUMIT vs 1.6% for placebo.
  • Obtain liver enzyme tests prior to initiation of OPSUMIT and repeat during treatment as clinically indicated.
  • Advise patients to report symptoms suggesting hepatic injury (nausea, vomiting, right upper quadrant pain, fatigue, anorexia, jaundice, dark urine, fever, or itching).
  • If clinically relevant aminotransferase elevations occur, or if elevations are accompanied by an increase in bilirubin >2 x ULN, or by clinical symptoms of hepatotoxicity, discontinue OPSUMIT. Consider re-initiation of OPSUMIT when hepatic enzyme levels normalize in patients who have not experienced clinical symptoms of hepatotoxicity.

Fluid Retention

  • Peripheral edema and fluid retention are known consequences of PAH and ERAs. In the pivotal PAH study SERAPHIN, edema was reported in 21.9% of the OPSUMIT group vs 20.5% for placebo.
  • Patients with underlying left ventricular dysfunction may be at particular risk for developing significant fluid retention after initiation of ERA treatment. In a small study of pulmonary hypertension due to left ventricular dysfunction, more patients in the OPSUMIT group developed significant fluid retention and had more hospitalizations due to worsening heart failure compared to placebo. Postmarketing cases of edema and fluid retention occurring within weeks of starting OPSUMIT, some requiring intervention with a diuretic or hospitalization for decompensated heart failure, have been reported.
  • Monitor for signs of fluid retention after OPSUMIT initiation. If clinically significant fluid retention develops, evaluate the patient to determine the cause and the possible need to discontinue OPSUMIT.

Hemoglobin Decrease

  • Decreases in hemoglobin concentration and hematocrit have occurred following administration of other ERAs and in clinical studies with OPSUMIT. These decreases occurred early and stabilized thereafter.
  • In the SERAPHIN study, OPSUMIT caused a mean decrease in hemoglobin (from baseline to 18 months) of about 1.0 g/dL vs no change in the placebo group. A decrease in hemoglobin to below 10.0 g/dL was reported in 8.7% of the OPSUMIT group vs 3.4% for placebo. Decreases in hemoglobin seldom require transfusion.
  • Initiation of OPSUMIT is not recommended in patients with severe anemia. Measure hemoglobin prior to initiation of treatment and repeat during treatment as clinically indicated.

Pulmonary Edema with Pulmonary Veno-occlusive Disease (PVOD)

Should signs of pulmonary edema occur, consider the possibility of associated PVOD. If confirmed, discontinue OPSUMIT.

Decreased Sperm Counts

OPSUMIT, like other ERAs, may have an adverse effect on spermatogenesis. Counsel men about potential effects on fertility.

ADVERSE REACTIONS

Most common adverse reactions (more frequent than placebo by ≥3%) were anemia (13% vs 3%), nasopharyngitis/pharyngitis (20% vs 13%), bronchitis (12% vs 6%), headache (14% vs 9%), influenza (6% vs 2%), and urinary tract infection (9% vs 6%).

DRUG INTERACTIONS

  • Strong inducers of CYP3A4 such as rifampin significantly reduce macitentan exposure. Concomitant use of OPSUMIT with strong CYP3A4 inducers should be avoided.
  • Strong inhibitors of CYP3A4 like ketoconazole approximately double macitentan exposure. Many HIV drugs like ritonavir are strong inhibitors of CYP3A4. Avoid concomitant use of OPSUMIT with strong CYP3A4 inhibitors. Use other PAH treatment options when strong CYP3A4 inhibitors are needed as part of HIV treatment.

View full Prescribing Information for OPSUMIT® (macitentan), including BOXED WARNING for embryo-fetal toxicity.

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IMPORTANT SAFETY INFORMATION

BOXED WARNING: EMBRYO-FETAL TOXICITY

  • Do not administer OPSUMIT to a pregnant female because it may cause fetal harm.
  • Females of reproductive potential: Exclude pregnancy before the start of treatment, monthly during treatment, and 1 month after stopping treatment. Prevent pregnancy during treatment and for one month after stopping treatment by using acceptable methods of contraception.
  • For all female patients, OPSUMIT is available only through a restricted program called the OPSUMIT Risk Evaluation and Mitigation Strategy (REMS).

INDICATION

OPSUMIT is an endothelin receptor antagonist (ERA) indicated for the treatment of pulmonary arterial hypertension (PAH, WHO Group I) to reduce the risks of disease progression and hospitalization for PAH.

Effectiveness was established in a long-term study in PAH patients with predominantly WHO Functional Class II-III symptoms treated for an average of 2 years. Patients had idiopathic and heritable PAH (57%), PAH caused by connective tissue disorders (31%), and PAH caused by congenital heart disease with repaired shunts (8%).