Iloprost is a medication used to treat pulmonary arterial hypertension (PAH), scleroderma, Raynauds phenomenon and other diseases in which the blood vessels are constricted and blood cannot flow to the tissues. This damages the tissues and causes high blood pressure. There is ongoing research into using it as a frostbite treatment. Iloprost works by opening (dilating) the blood vessels to allow the blood to flow through again. It was developed by the pharmaceutical company Schering AG and is marketed by Bayer Schering Pharma AG in Europe and Actelion Pharmaceuticals in the USA. Iloprost is given via inhalation, and a therapeautic benefit of the drug is that a very low dose is required because of the deposition in the lung. Iloprost has few systemic side effects for that reason. Clinical pharmacology
Iloprost is a synthetic analogue of prostacyclin PGI2. Iloprost dilates systemic and pulmonary arterial vascular beds. It also affects platelet aggregation but the relevance of this effect to the treatment of pulmonary hypertension is unknown. The two diastereoisomers of iloprost differ in their potency in dilating blood vessels, with the 4S isomer substantially more potent than the 4R isomer. While Iloprost is an analog of PGI2 that activates PGI2s receptor, the prostacyclin receptor, to stimulate vasodilation, it has little selectivity in that it binds to and activates all four receptors for prostaglandin E2 viz., prostaglandin EP1 receptor, prostaglandin EP2 receptor, prostaglandin EP3 receptor, and prostaglandin EP4 receptor. Activation of the EP2 and EP4 receptors cause vasodilation but activation of the EP3 receptor causes vasoconstriction.
Should signs of pulmonary edema occur when inhaled iloprost is administered in patients with pulmonary hypertension, the treatment should be stopped immediately. This may be a sign of pulmonary venous hypertension. See also
Pulmonary arterial hypertension (PAH)
Raynauds phenomenon
Scleroderma

References
Ventavis Package insert prescribing information available in PDF format. Olschewski, Horst; Simonneau, Gerald; Galiè, Nazzareno; Higenbottam, Timothy; Naeije, Robert; Rubin, Lewis J.; Nikkho, Sylvia; Speich, Rudolf; Hoeper, Marius M.; Behr, Jürgen; Winkler, Jörg; Sitbon, Olivier; Popov, Wladimir; Ghofrani, H. Ardeschir; Manes, Alessandra; Kiely, David G.; Ewert, Ralph; Meyer, Andreas; Corris, Paul A.; Delcroix, Marion; Gomez-Sanchez, Miguel; Siedentop, Harald; Seeger, Werner (August 1, 2002). "Inhaled Iloprost for Severe Pulmonary Hypertension". New England Journal of Medicine. 347 (5): 322–329. doi:10.1056/NEJMoa020204. PMID 12151469. ATS 2005. The International Conference of the American Thoracic Society. 20–25 May 2005. San Diego, CA. Meizer, Roland; Meraner, Dominik; Meizer, Elisbeth; Radda, Christian; Landsiedl, Franz; Aigner, Nicolas (Jan 2009). "Outcome of painful bone marrow edema of the femoral head following treatment with parenteral iloprost". Indian Journal of Orthopaedics. 43 (1): 36–9. doi:10.4103/0019-5413.45321. PMC 2739485. PMID 19753177. External links
"Iloprost". Drug Information Portal. U.S. National Library of Medicine.