Pulmonary Arterial Hypertension is a rare and progressive condition that compromises pulmonary circulation and can lead to right ventricular failure. Despite recent advances in diagnosis and treatment, the median survival of patients is only 2.8 years. The treatment for this disease is based on drugs that act on three main pathways: prostacyclin, endothelin, and nitric oxide. Iloprost, a prostacyclin analogue available in an inhaled form, is an important and well-established treatment. However, its mandatory frequent administration, the need for a specific inhalation technique, and its adverse event profile make its use complex. Although pharmacotherapeutic and inhalation technique follow-up by a qualified professional is widely studied in diseases like asthma and COPD, its application in Pulmonary Arterial Hypertension still lacks evidence. Thus, this study aims to evaluate how a pharmacist's intervention can improve treatment adherence, mitigate side effects and difficulties associated with inhalation, in addition to optimizing clinical and hemodynamic outcomes in patients with Pulmonary Arterial Hypertension using iloprost.

Inclusion Criteria:

• "Adult patients aged ≥ 18 years, treated at the referral center for PH management at the Heart Institute of the University of São Paulo Medical School, with an invasive confirmed diagnosis of PAH (mean pulmonary arterial pressure [mPAP] greater than 20 mmHg at rest, pulmonary vascular resistance [PVR] equal to or greater than 2 Wood units, and pulmonary capillary wedge pressure [PCWP] equal to or less than 15 mmHg), and who have been using Iloprost.

Exclusion Criteria:

• Patients who are unable to perform the 6-minute walk test (6MWT) or who have experienced gastrointestinal bleeding within the 12 weeks prior to the start of the study will be excluded.