Macitentan is an orally active, dual endothelin receptor antagonist with tissue targeting properties. Macitentan inhibits both ETA and ETB receptors and prevents them from binding to ET-1. Macitentan displays high affinity and sustained occupancy of the ET receptors in human pulmonary arterial smooth muscle cells. One of the metabolites of macitentan is also pharmacologically active at the ET receptors and is estimated to be about 20% as potent as the parent drug in vitro. Macitentan is approved in the EU (as monotherapy or combination therapy) for the long-term treatment of pulmonary arterial hypertension (PAH) in adults of WHO functional class II or III, and in the USA for the treatment of PAH (WHO group I) to delay disease progression and reduce hospitalization for PAH.

Iloprost is a second generation structural analog of prostacyclin (PGI) with about ten-fold greater potency than the first generation stable analogs, such as carbaprostacyclin. Iloprost binds with equal affinity to human prostacyclin (Prostanoid IP) and prostaglandin EP1 receptors. Iloprost constricts the ilium and fundus circular smooth muscle as strongly as prostaglandin E2 (PGE2) itself. Iloprost inhibits the ADP, thrombin, and collagen-induced aggregation of human platelets. In whole animals, iloprost acts as a vasodilator, hypotensive, antidiuretic, and prolongs bleeding time. All of these properties help to antagonize the pathological changes that take place in the small pulmonary arteries of patients with pulmonary hypertension. Used for the treatment of pulmonary arterial hypertension.

Vardenafil (Levitra) is an oral therapy for the treatment of erectile dysfunction. It is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). Penile erection is a hemodynamic process initiated by the relaxation of smooth muscle in the corpus cavernosum and its associated arterioles. During sexual stimulation, nitric oxide is released from nerve endings and endothelial cells in the corpus cavernosum. Nitric oxide activates the enzyme guanylate cyclase resulting in increased synthesis of cyclic guanosine monophosphate (cGMP) in the smooth muscle cells of the corpus cavernosum. The cGMP in turn triggers smooth muscle relaxation, allowing increased blood flow into the penis, resulting in erection. The tissue concentration of cGMP is regulated by both the rates of synthesis and degradation via phosphodiesterases (PDEs). The most abundant PDE in the human corpus cavernosum is the cGMPspecific phosphodiesterase type 5 (PDE5); therefore, the inhibition of PDE5 enhances erectile function by increasing the amount of cGMP.

Tadalafil is used to treat male erectile dysfunction (impotence) and pulmonary arterial hypertension (PAH). Part of the physiological process of erection involves the release of nitric oxide (NO) in the corpus cavernosum. This then activates the enzyme guanylate cyclase which results in increased levels of cyclic guanosine monophosphate (cGMP), leading to smooth muscle relaxation in the corpus cavernosum, resulting in increased inflow of blood and an erection. Tadalafil is a potent and selective inhibitor of cGMP specific phosphodiesterase type 5 (PDE5) which is responsible for degradation of cGMP in the corpus cavernosum. This means that, with tadalafil on board, normal sexual stimulation leads to increased levels of cGMP in the corpus cavernosum which leads to better erections. Without sexual stimulation and no activation of the NO/cGMP system, tadalafil should not cause an erection.Tadalafil inhibits the cGMP specific phosphodiesterase type 5 (PDE5) which is responsible for degradation of cGMP in the corpus cavernosum located around the penis. Penile erection during sexual stimulation is caused by increased penile blood flow resulting from the relaxation of penile arteries and corpus cavernosal smooth muscle. This response is mediated by the release of nitric oxide (NO) from nerve terminals and endothelial cells, which stimulates the synthesis of cGMP in smooth muscle cells. Cyclic GMP causes smooth muscle relaxation and increased blood flow into the corpus cavernosum. The inhibition of phosphodiesterase type 5 (PDE5) by tadalafil enhances erectile function by increasing the amount of cGMP. Tadalafil is used for the treatment of erectile dysfunction.

Imatinib (GLEEVEC®) is a tyrosine kinase inhibitor and antineoplastic agent that inhibits the BCR-ABL tyrosine kinase, the constitutive abnormal tyrosine kinase created by the Philadelphia chromosome abnormality in chronic myeloid leukaemia (CML). It inhibits proliferation and induces apoptosis in BCR-ABL positive cell lines as well as fresh leukemic cells from Philadelphia chromosome positive CML. Imatinib (GLEEVEC®) inhibits colony formation in assays using ex vivo peripheral blood and bone marrow samples from CML patients. It is also an inhibitor of the receptor tyrosine kinases for platelet-derived growth factor (PDGF) and stem cell factor (SCF), c-kit, and inhibits PDGF- and SCF-mediated cellular events. In vitro, imatinib (GLEEVEC®) inhibits proliferation and induces apoptosis in gastrointestinal stromal tumor (GIST) cells, which express an activating c-kit mutation.

Pentaerythritol tetranitrate is an organic nitrate that has been used for the treatment of angina pectoris. Upon administration, the drug undergoes exstensive metabolism to NO which causes vasodilation and the relaxation of smooth muscle cells. The compound belongs to a familiy of explosive substances and may be used accordingly.

Ralinepag is a cyclohexyl amide derivative patented by Arena Pharmaceuticals, Inc. as agonists of the human prostacyclin (PGI2) receptor useful for the treatment of pulmonary arterial hypertension. Ralinepag shows selectivity in both binding and functional assays with respect to most members of the prostanoid receptor family and a more modest 30-50-fold selectivity over the EP3 receptor. Ralinepag had an excellent PK profile across species. Enterohepatic recirculation most probably contributes to a concentration-time profile after oral administration in the cynomolgus monkey that showed a very low peak-to-trough ratio. Phase III clinical trial is currently ongoing.

2-Cyano-3,12-dioxooleana-1,9-diene-28-oic acid (CDDO, also known as Bardoxolone) is a synthetic triterpenoid that displays potent anti-inflammatory and antitumorigenic activities. CDDO was in the clinical trial phase I for the treatment patients with Solid tumors and leukemia, but that studies were discontinued. It is known, that CDDO blocks the cellular synthesis of inducible nitric oxide synthase and inducible COX-2. In addition, was discovered, that CDDO disrupted intracellular redox balance and thereby induce apoptosis. Moreover, CDDO is a ligand for peroxisome proliferator-activated receptor that it induces genes regulated by Nrf2, including heme oxygenase-1 and eotaxin-1, which play a role in antioxidant response element signaling activity.

2-Methoxyestradiol (2ME2) is a natural metabolite of endogenous estrogen hormone 17β-estradiol in human and devoid of estrogenic activity. It is a drug that prevents the formation of new blood vessels that tumors need in order to grow (angiogenesis). It has undergone Phase 1 clinical trials against breast cancers. Preclinical models also suggest that 2ME2 could also be effective against inflammatory diseases such as rheumatoid arthritis. 2-Methoxyestradiol is an angiogenesis inhibitor, and has been shown to attack both tumor cells and their blood supply in preclinical testing. Presently, it is an investigational drug under various phases of clinical trials alone or in combination therapy. Its anticancer activity has been attributed to its antitubulin, antiangiogenic, pro-apoptotic and ROS induction properties. 2-Methoxyestradiol shows strong cytotoxic effect on estrogen dependent and independent cancerous cells, which is mainly due to disruption of microtubule process and p53 induced apoptosis through caspase, reactive oxygen species (ROS), superoxide dismutase (SOD) and nitric oxide synthase. 2-Methoxyestradiol inhibits tubulin polymerisation by binding to colchicine binding site of the tubulin and arrests cell cycle at G2/M-phase.