Tyvaso Mechanism of Action

A dysregulation of the prostacyclin metabolic pathway has been shown in patients with PAH. This can lead to narrowing of the pulmonary arteries, resulting in increased pulmonary vascular resistance. Mimicking some of the effects of native prostacyclin, Tyvaso acts through the prostacyclin pathway to help alleviate this dysregulation.^1-4

The major pharmacologic actions of treprostinil are⁴

• Direct vasodilation of pulmonary and systemic arterial vascular beds
• Inhibition of platelet aggregation

Tyvaso is delivered noninvasively, directly to the lungs⁴

• Ultrasonic nebulizers deliver prostacyclin analogues directly to distal airspaces in close proximity to resistance pulmonary arterioles—helping overcome lower levels of prostacyclin synthesis^4-7
• Some common adverse events of Tyvaso include cough, headache, throat irritation/pharyngolaryngeal pain, nausea, flushing, and syncope⁴

Indications

Tyvaso (treprostinil) is a prostacyclin vasodilator indicated for the treatment of pulmonary arterial hypertension (PAH) (WHO Group 1) to improve exercise ability. Studies establishing effectiveness included predominately 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

• The efficacy of Tyvaso has not been established in patients with significant underlying lung disease (such as asthma or chronic obstructive pulmonary disease). Patients with acute pulmonary infections should be carefully monitored to detect any worsening of lung disease and loss of drug effect 
• Tyvaso is a pulmonary and systemic vasodilator. In patients with low systemic arterial pressure, Tyvaso may cause symptomatic hypotension
• Titrate slowly in patients with hepatic or renal insufficiency, as exposure to treprostinil may be increased in these patients
• Tyvaso inhibits platelet aggregation and increases the risk of bleeding
• Co-administration of the cytochrome P450 (CYP) 2C8 enzyme inhibitor gemfibrozil may increase exposure to treprostinil. Co-administration of the CYP2C8 enzyme inducer rifampin may decrease exposure to treprostinil. Increased exposure is likely to increase adverse events, 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
• Co-administration of the CYP2C8 enzyme inhibitor gemfibrozil increases exposure to oral treprostinil. Co-administration of the CYP2C8 enzyme inducer rifampin decreases exposure to oral 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

Adverse Reactions

• The most common adverse reactions seen with Tyvaso in ≥4% of PAH patients and more than 3% greater than placebo in the placebo-controlled clinical 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 ≥10% of patients were dizziness and diarrhea

TRIUMPH = TReprostinil Sodium Inhalation Used in the Management of Pulmonary Arterial Hypertension.

• 12-week, multicenter, randomized, double-blind trial of Tyvaso or placebo added to oral monotherapy (bosentan or sildenafil)
• 235 clinically stable patients (81% female, 19% male) were NYHA FC III (98%) or IV (2%) at baseline, with 6MWD between 200 m and 450 m
• Enrolled patients were on a stable course of bosentan or sildenafil; “stable” was defined as an unchanged dose of oral therapy for ≥3 months prior to initiating Tyvaso
• Oral therapy was continued throughout the study in both treatment arms

Dosage and Titration

• Dosing should be titrated to the target dose of 9 breaths, 4x daily¹
• Begin with 3 breaths per treatment session, and increase by 3 breaths per session at 1- to 2-week intervals until the maximum recommended dose of 9 breaths per treatment session is reached¹
• Modify titration schedule as needed based on patient tolerance. If starting dose of 3 breaths is not tolerated, reduce to 1 to 2 breaths and subsequently increase to 3 breaths as tolerated⁴

Individualized titration for patients⁴

Please see the Full Prescribing Information, Patient Product Information, and the TD-100 and TD-300 Tyvaso Inhalation System Instructions for Use manuals.
For additional information about Tyvaso, visit www.tyvaso.com or call 1-877-UNITHER (1-877-864-8437).

References: 1. Humbert M, Sitbon O, Simonneau G. Treatment of pulmonary arterial hypertension. N Engl J Med. 2004;351(14):1425-1436. 2. Michelakis ED, Wilkins MR, Rabinovitch M. Emerging concepts and translational priorities in pulmonary arterial hypertension. Circulation. 2008;118(14):1486-1495. 3. Bogaard HJ, Abe K, Noordegraaf AV, Voelkel NF. The right ventricle under pressure: cellular and molecular mechanisms of right-heart failure in pulmonary hypertension. Chest. 2009;135(3):794-804. 4. Tyvaso [package insert]. Research Triangle Park, NC: United Therapeutics Corporation; 2016. 5. Channick RN, Voswinckel R, Rubin LJ. Inhaled treprostinil: a therapeutic review. Drug Des Devel Ther. 2011;5:1-10. 6. McLaughlin V V, McGoon MD. Pulmonary arterial hypertension. Circulation. 2006;114(13):1417-1431. 7. Data on file. United Therapeutics Corporation. Research Triangle Park, NC. October 2008. 7. McLaughlin VV, Benza RL, Rubin LJ, et al. Addition of inhaled treprostinil to oral therapy for pulmonary arterial hypertension: a randomized controlled clinical trial. J Am Coll Cardiol. 2010;55(18):1915-1922.