Selexipag

Introduction Overview

Generic Name

selexipag

Brand Name

Uptravi

Dosage Form

Oral tablets and intravenous injection

Drug Class

Agents for pulmonary hypertension

Pharmacokinetics

Absorption:
Selexipag is rapidly absorbed following oral administration, with peak plasma concentrations typically achieved within 1 to 3 hours. Its absorption is not significantly affected by food intake, allowing administration with or without meals, which improves patient compliance. The drug exhibits linear pharmacokinetics over the therapeutic dosing range, facilitating predictable plasma levels during dose titration. Selexipag is a prodrug that undergoes extensive hydrolysis primarily by carboxylesterases during absorption, generating the active metabolite ACT-333679, which is responsible for its pharmacological effects.

Distribution:
The volume of distribution for selexipag and its active metabolite indicates moderate distribution into tissues. Both compounds demonstrate moderate plasma protein binding (~99%), mainly to albumin, which may impact drug interactions with other highly protein-bound agents. Importantly, selexipag and ACT-333679 penetrate pulmonary vascular tissues effectively to exert their therapeutic action. Distribution is not extensively altered by age, sex, or race, although considerations are warranted in hepatic impairment where protein binding and tissue distribution may vary.

Metabolism:
Selexipag undergoes rapid and extensive metabolism primarily via hydrolysis to its active metabolite ACT-333679. Subsequently, both selexipag and ACT-333679 are biotransformed mainly via the cytochrome P450 enzyme CYP2C8, and to a lesser extent CYP3A4, through oxidation and glucuronidation pathways. The formation of inactive metabolites facilitates clearance. Concomitant use of CYP2C8 inhibitors (e.g., gemfibrozil) significantly increases exposure to the active metabolite, necessitating dose adjustments. Inducers of these enzymes can reduce efficacy through increased clearance.

Elimination:
Uptravi and its metabolites are primarily eliminated via renal (approximately 93%) and fecal excretion routes. The elimination half-life of the active metabolite is approximately 7 to 13 hours, supporting twice-daily dosing. Renal impairment may modestly affect clearance, thus dose titration and monitoring are advised. Hepatic impairment also impacts metabolism and clearance, with moderate to severe impairment contraindicating use due to increased systemic exposure and risk of adverse events. Overall, elimination kinetics support steady-state plasma levels with twice-daily administration and allow for flexible dose adjustments based on tolerance.

Dosage Forms

Available Dosage Forms:
Uptravi is available as oral tablets in multiple strength formulations to facilitate individualized dose titration and maintenance therapy. The tablet strengths include 200 mcg, 400 mcg, 600 mcg, 800 mcg, 1000 mcg, 1200 mcg, 1400 mcg, and 1600 mcg. Additionally, an intravenous (IV) formulation is available for patients unable to take oral medications, allowing administration by healthcare providers.

Dosages for Adults and Adolescents:
The recommended initial dose of Uptravi for adults with pulmonary arterial hypertension (PAH) is 200 mcg taken orally twice daily. Dose titration occurs in 200 mcg increments twice daily at weekly intervals based on individual tolerance, aiming to reach the highest tolerated dose up to a maximum of 1600 mcg twice daily. If a patient experiences intolerance at a certain dose, reduction to the last tolerated dose is advised. The dosing regimen supports gradual adaptation to minimize side effects while maximizing therapeutic benefit. Although clinical approval primarily concerns adults, titration and dosing adjustments should be carefully managed in adolescents under medical supervision.

Specific Patient Populations:
In patients with hepatic impairment, use of Uptravi is contraindicated in moderate to severe cases due to elevated systemic exposure and increased risk of adverse reactions. Caution and close monitoring are necessary in patients with mild hepatic dysfunction. Dose adjustments in renal impairment have not been extensively studied; however, monitoring is recommended. The intravenous form of selexipag is indicated for patients unable to take oral therapy, such as during hospitalization or critical illness. Pregnancy and breastfeeding are not recommended during treatment due to unknown effects on the fetus and infant. Pediatric use is not well established, and safety has not been confirmed in this population.

Mechanism Of Action

Selexipag is a selective prostacyclin receptor (IP receptor) agonist that mimics the action of endogenous prostacyclin, a potent vasodilator and inhibitor of smooth muscle cell proliferation. By selectively binding to the IP receptor on pulmonary arterial smooth muscle cells, selexipag activates adenylate cyclase via G-protein coupling, leading to increased intracellular cyclic adenosine monophosphate (cAMP) levels. Elevated cAMP causes relaxation of vascular smooth muscle, resulting in vasodilation specifically in the pulmonary circulation. This targeted effect reduces pulmonary vascular resistance and lowers pulmonary arterial pressure.

At the cellular level, selexipag’s activation of the IP receptor also inhibits platelet aggregation and exerts antiproliferative effects on vascular remodeling, which are critical in the pathogenesis of pulmonary arterial hypertension (PAH). The drug's ability to reduce pathological remodeling contributes to long-term disease modification beyond immediate hemodynamic improvements. Unlike prostacyclin itself, selexipag has enhanced stability and oral bioavailability, allowing flexible dosing and increased patient convenience.

Biochemically, selexipag’s active metabolite ACT-333679 retains high affinity and selectivity for the IP receptor, displaying a longer half-life compared to the parent drug, thereby sustaining therapeutic action between doses. Comparative studies show selexipag achieves similar pulmonary vasodilatory effects but with an improved safety profile relative to continuous intravenous prostacyclin analogs, which often require complex administration setups.

Clinical trials demonstrate that selexipag effectively delays disease progression and reduces hospitalization risk for PAH patients by leveraging its vasodilatory and antiproliferative mechanisms. The mechanism underpins its role as an adjunctive therapy in PAH, frequently combined with endothelin receptor antagonists and phosphodiesterase type 5 inhibitors to address the multifactorial nature of pulmonary hypertension.

Pharmacological Actions

Selective agonism of the prostacyclin IP receptor leads to pulmonary vasodilation.
Increases intracellular cyclic AMP in vascular smooth muscle cells causing relaxation.
Inhibits platelet aggregation, reducing thrombotic risk in pulmonary vessels.
Exerts antiproliferative effects on vascular smooth muscle, slowing disease progression.
Lowers pulmonary arterial pressure and pulmonary vascular resistance.
Improves cardiac output in patients with pulmonary arterial hypertension.
Oral bioavailability allows for convenient twice-daily dosing.
Active metabolite extends duration of action, enhancing therapeutic effect.
Does not activate prostaglandin E receptors, minimizing off-target side effects.
Provides disease-modifying effects by reducing vascular remodeling.
Suitable for use in combination therapy for PAH management.
Demonstrates dose-dependent efficacy in improving exercise capacity.
Reduces risk of hospitalization due to PAH progression.
Improves WHO functional class and quality of life in PAH patients.

Therapeutic Or Clinical Uses

Treatment of pulmonary arterial hypertension (PAH) WHO Group 1 in adults.
Delayed progression of PAH disease by reducing vascular remodeling.
Reduction of risk for hospitalization related to PAH.
Adjunctive therapy combined with endothelin receptor antagonists and PDE5 inhibitors.
Improvement in exercise capacity and functional status in PAH patients.
Management of symptoms associated with elevated pulmonary arterial pressure.
Use in patients unable to tolerate or access intravenous prostacyclin therapies.
Treatment option for patients requiring oral prostacyclin receptor agonist therapy.
Potential use in patients with PAH associated with connective tissue diseases.
Alternative to continuous infusion therapies offering greater convenience.
As part of a comprehensive PAH treatment regimen to improve hemodynamics.
Facilitation of outpatient management for chronic pulmonary hypertension.
Use in patients with NYHA/WHO functional class II to III symptoms.
Reduction of pulmonary vascular resistance to improve right heart function.

Side Or Adverse Effects

Headache, frequently reported and sometimes dose limiting.
Jaw pain and discomfort during dosing titration.
Muscle pain and myalgia in arms or legs.
Joint pain (arthralgia), affecting patient adherence.
Flushing characterized by warmth, redness, or tingling sensation.
Rash or other dermatological reactions.
Anemia with symptoms including pallor, fatigue, and shortness of breath.
Nausea and vomiting affecting gastrointestinal tolerance.
Loss of appetite potentially leading to weight loss.
Diarrhea, occasionally resulting in dehydration.
Injection site reactions such as pain, redness, or swelling with IV form.
Signs of allergic reaction including urticaria, swelling of face or throat.
New or worsening lung symptoms including anxiety, wheezing, and cough with foamy mucus.
Potential risk of hypotension especially with concomitant antihypertensives.
Rare but serious adverse effects include pulmonary veno-occlusive disease exacerbation.

Precautions

Use caution in patients with hepatic impairment; contraindicated in moderate to severe liver disease.
Careful dose titration to monitor for intolerance and side effects.
Avoid abrupt discontinuation to prevent worsening of pulmonary hypertension.
Monitor for signs of anemia and new respiratory symptoms during therapy.
Avoid concomitant use with strong CYP2C8 inhibitors unless dosing adjustments are made.
Use caution when combined with anticoagulants due to potential bleeding risk.
Pregnant women should avoid Uptravi unless the potential benefit justifies the risk.
Do not breastfeed during treatment due to unknown drug excretion in milk.
Patient education on the importance of adherence and not missing doses.
Regular monitoring of liver function tests during therapy.
Avoid use in pulmonary veno-occlusive disease as it can worsen the condition.
Ensure adequate hydration to minimize gastrointestinal adverse effects.
Dose adjustments may be necessary in elderly or those with comorbid conditions.
Advise patients to report any new or worsening respiratory or cardiovascular symptoms.
Pharmacogenomic variability may influence metabolism and response.

Warnings

Contraindicated in patients with known hypersensitivity to selexipag or any component.
Risk of clinical deterioration if therapy is discontinued abruptly.
Potential for serious drug interactions, particularly with CYP2C8 inhibitors like gemfibrozil.
May exacerbate pulmonary veno-occlusive disease causing severe pulmonary edema.
Use with caution in patients taking clopidogrel due to interaction risk.
Pregnancy category unknown; potential teratogenic effects cannot be ruled out.
Not recommended during breastfeeding owing to lack of safety data.
May cause hypotension, warranting careful blood pressure monitoring.
Use under strict medical supervision in patients with severe hepatic impairment.
Potential risks associated with bleeding, especially with concurrent antithrombotic therapy.
Monitor closely for signs of heart failure exacerbation.
Patients should inform healthcare providers of all medications to avoid harmful interactions.
Do not use in pediatric patients due to insufficient safety and efficacy data.
Risk of anemia necessitates periodic complete blood count assessment.
Report any signs of allergic reactions immediately as emergency treatment may be required.

Contraindication

Known hypersensitivity or allergy to selexipag or any formulation components.
Moderate to severe hepatic impairment.
Pulmonary veno-occlusive disease due to risk of clinical worsening.
Concurrent use with strong CYP2C8 inhibitors (e.g., gemfibrozil) without appropriate dose adjustment.
Pregnancy unless potential benefits outweigh risks, due to unknown fetal safety.
Breastfeeding mothers given unknown excretion in human milk and potential for adverse effects.
Inability to comply with dose titration and monitoring regimen.
Hypotension or unstable cardiovascular status where vasodilation may increase risks.
Use in pediatric patients under 18 years lacking established safety data.
Severe hypersensitivity reactions to prostacyclin analogs or related compounds.
Active bleeding disorders where platelet inhibition could exacerbate bleeding.
Severe renal impairment requiring dialysis until further studies clarify safety.
Concomitant use of contraindicated interacting medications without dose adjustments.
History of severe adverse reactions to prostacyclin receptor agonists.
Situations where oral or intravenous administration is not feasible and no alternative exists.

Drug Interactions

Gemfibrozil (CYP2C8 inhibitor) increases selexipag metabolism exposure; coadministration contraindicated.
Clopidogrel may interact affecting platelet function and bleeding risk.
Strong CYP2C8 inhibitors elevate active metabolite levels requiring dose modification.
CYP3A4 inducers such as rifampin may reduce selexipag plasma concentrations decreasing efficacy.
Concomitant use with anticoagulants increases bleeding risk due to additive antiplatelet effects.
Co-administration with other prostacyclin analogs or receptor agonists may potentiate adverse effects.
Use with vasodilators may cause additive hypotensive effects necessitating blood pressure monitoring.
Potential interactions with herbal supplements like St. John's Wort via CYP enzyme induction.
Non-steroidal anti-inflammatory drugs (NSAIDs) may enhance bleeding risks when combined.
Drugs affecting hepatic metabolism could alter selexipag pharmacokinetics.
Care with concurrent use of agents that affect platelet function, such as SSRIs.
Potential interaction with PDE5 inhibitors used for pulmonary hypertension requiring monitoring.
Pharmacodynamic interactions with antihypertensive agents require cautious dose adjustments.
Altered absorption not clinically significant with most foods; no major food-drug interactions.
Monitoring recommended when initiating or discontinuing interacting drugs.

Preparations Of The Drug

Oral tablets available in multiple strengths: 200 mcg, 400 mcg, 600 mcg, 800 mcg, 1000 mcg, 1200 mcg, 1400 mcg, and 1600 mcg.
Intravenous (IV) injection formulation for use when oral administration is not feasible.
Tablets are to be swallowed whole without crushing, chewing, or breaking to ensure proper dosing.
Tablets formulated for twice-daily dosing to maintain steady plasma concentrations.
Stored at room temperature, protected from moisture and heat to maintain stability.
Available in blister packs or bottles depending on manufacturer and dispensing requirements.
Injection preparation provided as sterile solution for intravenous infusion.
Dosage preparation protocols available for titration increments according to patient tolerance.
Manufacturer provides patient information leaflets detailing administration instructions.
Packaging includes safety seals to ensure product integrity during dispensing.
Specific formulations designed to optimize bioavailability and minimize gastrointestinal irritation.
Compatible compatible with standard intravenous fluids for infusion in clinical settings.
Oral tablets are non-enteric coated and do not require fasting conditions for intake.
Dose reduction recommended in certain clinical scenarios, with corresponding dose strengths available.
Strict storage and handling guidelines ensure maintenance of potency and efficacy.