Completed

A Phase 3, Randomized, Double-Blind, Placebo-Controlled Safety and Efficacy Study of Sitaxsentan Sodium (Thelin™) Treatment With an Open-Label Bosentan Arm in Patients With Pulmonary Arterial Hypertension (PAH)

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What is being tested

Data Collection

Who is being recruted

Pulmonary Arterial Hypertension
+5

+ Cardiovascular Diseases
+ Hypertension
From 12 to 75 Years
See all eligibility criteria
How is the trial designed

Treatment Study

Phase 3
Interventional
Study Start: May 2003
See protocol details

Summary

Principal SponsorEncysive Pharmaceuticals
Last updated: January 14, 2026
Sourced from a government-validated database.Claim as a partner
Study start date: May 1, 2003Actual date on which the first participant was enrolled.

The purpose of this study is to evaluate the safety and efficacy of Thelin™ (sitaxsentan sodium) as compared to placebo in the treatment of patients with PAH. A cohort of patients will be randomized to usual treatment with Tracleer® (bosentan) for observational comparisons of safety and efficacy.

Official TitleA Phase 3, Randomized, Double-Blind, Placebo-Controlled Safety and Efficacy Study of Sitaxsentan Sodium (Thelin™) Treatment With an Open-Label Bosentan Arm in Patients With Pulmonary Arterial Hypertension (PAH) 
NCT00080457
Principal SponsorEncysive Pharmaceuticals
Last updated: January 14, 2026
Sourced from a government-validated database.Claim as a partner

Protocol

This section provides details of the study plan, including how the study is designed and what the study is measuring.
Design Details
240 patients to be enrolledTotal number of participants that the clinical trial aims to recruit.
Treatment Study
These studies test new ways to treat a disease, condition, or health issue. The goal is to see if a new drug, therapy, or approach works better or has fewer side effects than existing options.

How participants are assigned to different groups/arms
In this clinical study, participants are placed into groups randomly, like flipping a coin. This ensures that the study is fair and unbiased, making the results more reliable. By assigning participants by chance, researchers can better compare treatments without external influences.

Other Ways to Assign Participants
Non-randomized allocation: Participants are assigned based on specific factors, such as their medical condition or a doctor's decision.
None (Single-arm trial): If the study has only one group, all participants receive the same treatment, and no allocation is needed.

How treatments are given to participants
Participants are divided into different groups, each receiving a specific treatment at the same time. This helps researchers compare how well different treatments work against each other.

Other Ways to Assign Treatments
Single-group assignment: Everyone gets the same treatment.
Cross-over assignment: Participants switch between treatments during the study.
Factorial assignment: Participants receive different combinations of treatments.
Sequential assignment: Participants receive treatments one after another in a specific order, possibly based on individual responses.
Other assignment: Treatment assignment does not follow a standard or predefined design.

How the interventions assigned to participants is kept confidential
Neither participants nor researchers know who is receiving which treatment. This is the most rigorous way to reduce bias, ensuring that expectations do not influence the results.

Other Ways to Mask Information
Open-label: Everyone knows which treatment is being given.
Single-blind: Participants do not know which treatment they are receiving, but researchers do.
Triple-blind: Participants, researchers, and outcome assessors do not know which treatment is given.
Quadruple-blind: Participants, researchers, outcome assessors, and care providers all do not know which treatment is given.

Eligibility

Researchers look for people who fit a certain description, called eligibility criteria: person's general health condition or prior treatments.
Conditions
Criteria
Any sexBiological sex of participants that are eligible to enroll.
From 12 to 75 YearsRange of ages for which participants are eligible to join.
Healthy volunteers not allowedIf individuals who are healthy and do not have the condition being studied can participate.
Conditions
Pathology
Pulmonary Arterial Hypertension
Cardiovascular Diseases
Hypertension
Hypertension, Pulmonary
Lung Diseases
Respiratory Tract Diseases
Vascular Diseases
Familial Primary Pulmonary Hypertension
Criteria

Inclusion Criteria: * Have a current diagnosis of symptomatic PAH classified by one of the following: 1. primary pulmonary hypertension (PPH) - also known as idiopathic pulmonary arterial hypertension (IPAH); 2. PAH associated with connective tissue diseases; 3. PAH associated with one of the following congenital heart defects: 1. repaired ASD, VSD or PDA greater than one year post-operative 2. un-repaired secundum ASD (with resting oxygen saturation greater than 88 percent in room air measured by oximeter) * World Health Organization (WHO) functional class II, III, IV * Greater than 12 and less than 75 years of age * Women of childbearing potential must be using two forms of medically acceptable contraception (at least one barrier method) * Have a cardiac catheterization within 6 months before study entry that shows the following values: 1. mean pulmonary artery pressure (PAPm) greater than 25 mmHg (at rest), 2. pulmonary capillary wedge pressure (PCWP) or left ventricular-end diastolic pressure less than 15 mmHg, and 3. pulmonary vascular resistance (PVR) greater than 3 mmHg/L/min. Exclusion Criteria: * Portal hypertension or chronic liver disease * ALT or AST levels greater than 1.5 times the upper limit of normal at the Screening Visit * Contraindication to treatment with an endothelin receptor antagonist * Recent history of abusing alcohol or illicit drugs * Chronic renal insufficiency * Pregnant or breastfeeding * Atrial septostomy within 30 days before study entry * Previous failure on bosentan because of safety concerns of the lack of clinical response

Study Centers

These are the hospitals, clinics, or research facilities where the trial is being conducted. You can find the location closest to you and its status.
This study has 1 location
Suspended
Encysive PharmaceuticalsHouston, United StatesSee the location
CompletedOne Study Center
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