PDE5A and pulmonary arterial hypertension: Tadalafil is a selective phosphodiesterase type 5 (PDE‐5) inhibitor approved by health authorities including the United States Food and Drug Administration5 and the European Medicines Agency6 under the brand name Adcirca® (20 mg film‐coated tablet) for the treatment of PAH at a recommended dose of 40 mg for adult PAH patients.