Furegrelate (previously known as U-63557A), a selective orally active thromboxane synthase inhibitor, with potential for the treatment of various diseases including hypertension, thrombosis, and renal disorders, arrhythmias, but these studies were discontinued.

Furegrelate (previously known as U-63557A), a selective orally active thromboxane synthase inhibitor, with potential for the treatment of various diseases including hypertension, thrombosis, and renal disorders, arrhythmias, but these studies were discontinued.

ICI-118551 is a selective β2 adrenergic receptor antagonist, that was originally developed for the regulation of blood pressure. ICI-118551 crosses the blood-brain barrier and it was in phase I clinical trials for the treatment of chronic anxiety. Currently, ICI-118,551 has no known therapeutic use in humans although it has been used widely in research to understand the action of the β2 adrenergic receptor, as few other specific antagonists for this receptor are known.

Ubenimex is a dipeptide, which specificallyinhibits the activity of leukotriene A4 hydrolase, aminopeptidase B and leucine aminopeptidase of the cell membrane. The drug was isolated from Streptomyces oliooreticuli in 1976 in Nippon Kayaku, Japan and approved for the treatment of acute non-lymphocytic leukemia under the name Bestatin. In the USA the drug is currentlu in Phase II for the treatment of pulmonary arterial hypertension and lymphedema.

Tezosentan (Veletri; Ro 61–0612) is a dual endothelin receptor antagonist that has been shown to improve cardiac output, decrease pulmonary capillary wedge pressure, and reduce pulmonary and systemic vascular resistance in initial clinical studies in acutely decompensated heart failure. Tezosentan is a water-soluble ET-1 receptor antagonist with high affinity to both ETA and ETB receptors but greater potency for the ETA receptor subtype. Clinical studies demonstrated mixed results for Tezosentan regarding its efficacy and tolerability in the management of decompensated heart failure. The side effects of Tezosentan include a headache, nausea, and hypotension.

Sitaxentan (TBC11251, trade name Thelin) is a potent and selective Endothelin A receptor antagonist. Sitaxentan was under development by Encysive Pharmaceuticals (now Pfizer) for use in the treatment of pulmonary hypertension, congestive heart failure and asthma. It was launched in the major markets of the European Union (EU) under name Thelin for the treatment of pulmonary arterial hypertension. In December 2010, Pfizer discontinued clinical trials of sitaxentan worldwide and initiated voluntary product withdrawal from markets where it is approved due to life-threatening idiosyncratic risk of liver injury.