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Treprostinil Mechanism of Action

The prostacyclin pathway is among the 3 therapeutic pathways for the treatment of PAH1-3

Targeting multiple pathogenic pathways is now standard of care.4

  • Endothelin pathway1
  • Nitric oxide pathway1,5
  • Prostacyclin pathway1,3

Treprostinil is a prostacyclin-class therapy3

Treprostinil mechanism of action

Treprostinil mechanism of action targets 3 of the pathologic changes that occur in PAH1,3,5,6

  1. Vasoconstriction

    Treprostinil directly dilates pulmonary and systemic arterial vascular beds

  2. Platelet aggregation

    Treprostinil inhibits platelet aggregation

  3. Smooth muscle proliferation

    Treprostinil inhibits smooth muscle cell proliferation

United Therapeutics offers treprostinil in 3 different forms—oral, inhaled, and pump—each designed to meet different needs.

PAH=pulmonary arterial hypertension; PH=pulmonary hypertension.

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SELECTED IMPORTANT SAFETY INFORMATION

  • Orenitram is Contraindicated in patients with severe hepatic impairment (Child Pugh Class C).
  • Tyvaso has a Warning and Precaution for patients with low systemic arterial pressure, as Tyvaso may produce symptomatic hypotension.
  • Remodulin has a Warning and Precaution for chronic intravenous (IV) infusions of Remodulin delivered using an external infusion pump with an indwelling central venous catheter, as they are associated with the risk of blood stream infections (BSI) and sepsis, which may be fatal. Therefore, continuous subcutaneous (SC) infusion is the preferred mode of administration.

Please see below for Indication, Important Safety information, and links to the Full Prescribing Information for Orenitram, TYVASO, and Remodulin.

SELECTED IMPORTANT SAFETY INFORMATION

  • Orenitram is Contraindicated in patients with severe hepatic impairment (Child Pugh Class C).
  • Tyvaso has a Warning and Precaution for patients with low systemic arterial pressure, as Tyvaso may produce symptomatic hypotension.
  • Remodulin has a Warning and Precaution for chronic intravenous (IV) infusions of Remodulin delivered using an external infusion pump with an indwelling central venous catheter, as they are associated with the risk of blood stream infections (BSI) and sepsis, which may be fatal. Therefore, continuous subcutaneous (SC) infusion is the preferred mode of administration.

Please see below for Indication, Important Safety Information, and links to the Full Prescribing Information for Orenitram, TYVASO, and Remodulin.

Orenitram® (treprostinil) Extended-Release Tablets

INDICATION

Orenitram is a prostacyclin mimetic indicated for treatment of pulmonary arterial hypertension (PAH) (WHO Group 1) to delay disease progression and to improve exercise capacity. The studies that established effectiveness included predominately patients with WHO functional class II-III symptoms and etiologies of idiopathic or heritable PAH (66%) or PAH associated with connective tissue disease (26%).

IMPORTANT SAFETY INFORMATION FOR ORENITRAM

CONTRAINDICATIONS

  • Avoid use of Orenitram in patients with severe hepatic impairment (Child Pugh Class C) due to increases in systemic exposure.

WARNINGS AND PRECAUTIONS

  • Abrupt discontinuation or sudden large reductions in dosage of Orenitram may result in worsening of PAH symptoms.
  • The Orenitram tablet shell does not dissolve. In patients with diverticulosis, Orenitram tablets can lodge in a diverticulum.

ADVERSE REACTIONS

  • In the 12-week, placebo-controlled, monotherapy study, and an event-driven placebo-controlled, combination therapy study, adverse reactions that occurred at rates at least 5% higher on Orenitram than on placebo included headache, diarrhea, nausea, vomiting, flushing, pain in jaw, pain in extremity, hypokalemia, abdominal discomfort, and upper abdominal pain.

DRUG INTERACTIONS

  • Co-administration of Orenitram and the CYP2C8 enzyme inhibitor gemfibrozil increases exposure to treprostinil; therefore, Orenitram dosage reduction may be necessary in these patients.

SPECIFIC POPULATIONS

  • Animal reproductive studies with Orenitram have shown an adverse effect on the fetus. There are no adequate and well-controlled studies with Orenitram in pregnant women.
  • It is not known whether treprostinil is excreted in human milk or if it affects the breastfed infant or milk production.
  • Safety and effectiveness of Orenitram in pediatric patients have not been established.
  • Use of Orenitram in patients aged 65 years and over demonstrated slightly higher absolute and relative adverse event rates compared to younger patients. Caution should be used when selecting a dose for geriatric patients.
  • There is a marked increase in the systemic exposure to treprostinil in hepatically impaired patients.

Please see Full Prescribing Information and Patient Information at orenitram.com or call 1-877-UNITHER (1-877-864-8437).

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TYVASO® (treprostinil) Inhalation Solution

INDICATION

TYVASO (treprostinil) is a prostacyclin mimetic indicated for the treatment of pulmonary arterial hypertension (PAH; WHO Group 1) to improve exercise ability. Studies establishing effectiveness predominately included patients with NYHA Functional Class III symptoms and etiologies of idiopathic or heritable PAH (56%) or PAH associated with connective tissue diseases (33%).

The effects diminish over the minimum recommended dosing interval of 4 hours; treatment timing can be adjusted for planned activities.

While there are long-term data on use of treprostinil by other routes of administration, nearly all controlled clinical experience with inhaled treprostinil has been on a background of bosentan (an endothelin receptor antagonist) or sildenafil (a phosphodiesterase type 5 inhibitor). The controlled clinical experience was limited to 12 weeks in duration.

IMPORTANT SAFETY INFORMATION FOR TYVASO

WARNINGS AND PRECAUTIONS

  • TYVASO is a pulmonary and systemic vasodilator. In patients with low systemic arterial pressure, TYVASO may produce symptomatic hypotension.
  • TYVASO inhibits platelet aggregation and increases the risk of bleeding.
  • Co-administration of a cytochrome P450 (CYP) 2C8 enzyme inhibitor (e.g., gemfibrozil) may increase exposure (both Cmax and AUC) to treprostinil. Co-administration of a CYP2C8 enzyme inducer (e.g., rifampin) may decrease exposure to treprostinil. Increased exposure is likely to increase adverse events associated with treprostinil administration, whereas decreased exposure is likely to reduce clinical effectiveness.

DRUG INTERACTIONS/SPECIFIC POPULATIONS

  • The concomitant use of TYVASO with diuretics, antihypertensives, or other vasodilators may increase the risk of symptomatic hypotension.
  • Human pharmacokinetic studies with an oral formulation of treprostinil (treprostinil diolamine) indicated that co-administration of the cytochrome P450 (CYP) 2C8 enzyme inhibitor, gemfibrozil, increases exposure (both Cmax and AUC) to treprostinil. Co-administration of the CYP2C8 enzyme inducer, rifampin, decreases exposure to treprostinil. It is unclear if the safety and efficacy of treprostinil by the inhalation route are altered by inhibitors or inducers of CYP2C8.
  • Limited case reports of treprostinil use in pregnant women are insufficient to inform a drug-associated risk of adverse developmental outcomes. However, pulmonary arterial hypertension is associated with an increased risk of maternal and fetal mortality. There are no data on the presence of treprostinil in human milk, the effects on the breastfed infant, or the effects on milk production.
  • Safety and effectiveness in pediatric patients have not been established.
  • Across clinical studies used to establish the effectiveness of TYVASO in patients with PAH and pulmonary hypertension associated with interstitial lung disease (PH-ILD), 268 (47.8%) patients aged 65 years and over were enrolled. The treatment effects and safety profile observed in geriatric patients were similar to younger patients. In general, dose selection for an elderly patient should be cautious, reflecting the greater frequency of hepatic, renal, or cardiac dysfunction, and of concomitant diseases or other drug therapy.

ADVERSE REACTIONS

Pulmonary Arterial Hypertension (WHO Group 1)

In a 12-week, placebo-controlled study (TRIUMPH I) of 235 patients with PAH (WHO Group 1 and nearly all NYHA Functional Class III), the most common adverse reactions seen with TYVASO in ≥4% of PAH patients and more than 3% greater than placebo in the placebo-controlled study were cough (54% vs 29%), headache (41% vs 23%), throat irritation/pharyngolaryngeal pain (25% vs 14%), nausea (19% vs 11%), flushing (15% vs <1%), and syncope (6% vs <1%). In addition, adverse reactions occurring in ≥4% of patients were dizziness and diarrhea.

Please see Full Prescribing Information, the TD-100 and TD-300 TYVASO® Inhalation System Instructions for Use manuals, and other additional information at www.tyvaso.com or call 1-877-UNITHER (1-877-864-8437).

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Remodulin® (treprostinil) Injection

INDICATION

Remodulin is a prostacyclin vasodilator indicated for the treatment of pulmonary arterial hypertension (PAH; WHO Group 1) to diminish symptoms associated with exercise. Studies establishing effectiveness included patients with NYHA Functional Class II-IV symptoms and etiologies of idiopathic or heritable PAH (58%), PAH associated with congenital systemic-to-pulmonary shunts (23%), or PAH associated with connective tissue diseases (19%).

In patients with PAH requiring transition from epoprostenol, Remodulin is indicated to diminish the rate of clinical deterioration. Consider the risks and benefits of each drug prior to transition.

IMPORTANT SAFETY INFORMATION FOR REMODULIN

WARNINGS AND PRECAUTIONS

  • Chronic intravenous (IV) infusions of Remodulin delivered using an external infusion pump with an indwelling central venous catheter are associated with the risk of blood stream infections (BSIs) and sepsis, which may be fatal. Therefore, continuous subcutaneous (SC) infusion is the preferred mode of administration.
  • Avoid abrupt withdrawal or sudden large reductions in dosage of Remodulin, which may result in worsening of PAH symptoms.
  • Titrate slowly in patients with hepatic or renal insufficiency, because such patients will likely be exposed to greater systemic concentrations relative to patients with normal hepatic or renal function.
  • Remodulin is a pulmonary and systemic vasodilator. In patients with low systemic arterial pressure, treatment with Remodulin may produce symptomatic hypotension.
  • Remodulin inhibits platelet aggregation and increases the risk of bleeding.

ADVERSE REACTIONS

  • In clinical studies of SC Remodulin infusion, the most common adverse events reported were infusion site pain and infusion site reaction (redness, swelling, and rash). These symptoms were sometimes severe and sometimes required treatment with narcotics or discontinuation of Remodulin. The IV infusion of Remodulin with an external infusion pump has been associated with a risk of blood stream infections, arm swelling, paresthesias, hematoma, and pain. Other common adverse events (≥3% more than placebo) seen with either SC or IV Remodulin were headache (27% vs. 23%), diarrhea (25% vs. 16%), nausea (22% vs. 18%), rash (14% vs. 11%), jaw pain (13% vs. 5%), vasodilatation (11% vs. 5%), edema(9% vs. 3%), and hypotension (4% vs. 2%).

DRUG INTERACTIONS

  • Remodulin dosage adjustment may be necessary if inhibitors or inducers of CYP2C8 are added or withdrawn.

SPECIFIC POPULATIONS

  • In patients with mild or moderate hepatic insufficiency, decrease the initial dose of Remodulin to 0.625 ng/kg/min of ideal body weight, and monitor closely. Remodulin has not been studied in patients with severe hepatic insufficiency.
  • Safety and effectiveness of Remodulin in pediatric patients have not been established.
  • It is unknown if geriatric patients respond differently than younger patients. Caution should be used when selecting a dose for geriatric patients.
  • There are no adequate and well-controlled studies with Remodulin in pregnant women. It is not known whether treprostinil is excreted in human milk or if it affects the breastfed infant or milk production.

Please see accompanying Full Prescribing Information for Remodulin.

For additional information, visit www.remodulin.com or call Customer Service at 1-877-UNITHER (1-877-864-8437).

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References: 1. Humbert M, Sitbon O, Simonneau G. Treatment of pulmonary arterial hypertension. N Engl J Med. 2004;351(14):1425-1436. 2. Clapp LH, Gurung R. The mechanistic basis of prostacyclin and its stable analogues in pulmonary arterial hypertension: role of membrane versus nuclear receptors. Prostaglandins Other Lipid Mediat. 2015;120:56-71. 3. Del Pozo R, Hernandez Gonzalez I, Escribano-Subías P. The prostacyclin pathway in pulmonary arterial hypertension: a clinical review. Expert Rev Respir Med. 2017;11(6):491-503. 4. Galiè N, Channick RN, Frantz RP, et al. Risk stratification and medical therapy of pulmonary arterial hypertension. Eur Respir J. 2019;53(1):1801889. doi:10.1183/13993003.01889-2018 5. Sitbon O, Morrell N. Pathways in pulmonary arterial hypertension: the future is here. Eur Respir Rev. 2012;21(126):321-327. 6. Clapp LH, Abu-Hanna JHJ, Patel JA. Diverse pharmacology of prostacyclin mimetics: implications for pulmonary hypertension. In: Nakanishi T, Baldwin HS, Fineman JR, Yamagishi H, eds. Molecular Mechanism of Congenital Heart Disease and Pulmonary Hypertension. Springer, Singapore; 2020:31-61. https://doi.org/10.1007/978-981-15-1185-1_5