Iloprost
[CAS 78919-13-8]

Identification

• Classification: API >> Hormone and endocrine-regulating drugs >> Prostaglandins
• Name: Iloprost
• Synonyms: 5-(Hexahydro-5-hydroxy-4-(3-hydroxy-4-methyl-1-octen-6-ynyl)-2(1H)-pentalenylidene)pentanoic acid
• Molecular Formula: C₂₂H₃₂O₄
• Molecular Weight: 360.49
• CAS Registry Number: 78919-13-8
• EC Number: 636-055-8
• SMILES: CC#CCC(C)[C@@H](/C=C/[C@H]1[C@@H](C[C@H]2[C@@H]1C/C(=C/CCCC(=O)O)/C2)O)O

Properties

• Density: 1.2±0.1 g/cm³ Calc.^*
• Boiling point: 539.2±50.0 °C 760 mmHg (Calc.)^*
• Flash point: 294.0±26.6 °C (Calc.)^*
• Solubility: Soluble in methyl acetate (Expl.)
• Index of refraction: 1.629 (Calc.)^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS06;GHS08 Danger
• Risk Statements: H301-H311-H331-H361
• Safety Statements: P203-P261-P262-P264-P270-P271-P280-P301+P316-P302+P352-P304+P340-P316-P318-P321-P330-P361+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	3	H301
Acute toxicity	Acute Tox.	3	H331
Acute toxicity	Acute Tox.	3	H311
Reproductive toxicity	Repr.	2	H361
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin irritation	Skin Irrit.	2	H315

chemBlink Chemical Story

Iloprost is a synthetic prostacyclin analogue. It illustrates a familiar design problem in drug chemistry: how to preserve useful biological recognition while changing a framework that is chemically fragile. Natural prostacyclin contains a hydrolysis-sensitive cyclic enol ether. Iloprost instead has a carbocyclic framework and retains side chains that allow it to mimic aspects of prostacyclin signaling. It is a different compound, not an epoprostenol salt or simply a more concentrated preparation of the natural mediator.

The actions associated with prostacyclin signaling include relaxation of vascular smooth muscle and inhibition of platelet aggregation. Those effects can be relevant to more than one clinical question, but a shared mechanism does not establish a new use. To assess a drug in a particular setting, it is necessary to consider which tissue is exposed, how the formulation delivers the compound, and what outcome the clinical evidence addresses.

The FDA chemistry review relates the intravenous Aurlumyn product to an earlier inhaled iloprost formulation, Ventavis. Both contain iloprost but present it through different dosage forms and routes. Aurlumyn's U.S. label describes use for severe frostbite in adults to reduce risk of digit amputation. The outcome concerns tissue injury in a specified context. It is distinct from an outcome that would be used to assess inhaled therapy in pulmonary vascular disease. Sharing a chemical identity does not make the products or their indications interchangeable.

This contrast makes iloprost a useful comparison with prostacyclin itself. The analogue addresses part of the chemical stability problem by altering the molecular framework, but formulation and clinical evaluation remain separate tasks. The chemical identity explains why the molecule belongs to a family. The labeled product establishes what was evaluated and for what purpose. Neither can be replaced by a claim about the family as a whole.

References:
1. FDA GSRS. Iloprost, CAS 78919-13-8. https://precision.fda.gov/uniisearch/srs/unii/JED5K35YGL
2. FDA. Aurlumyn chemistry review, NDA 217933. https://www.accessdata.fda.gov/drugsatfda_docs/nda/2025/217933Orig1s000ChemR.pdf
3. DailyMed. AURLUMYN prescribing information. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=34036fc0-6832-d066-e063-6394a90a18a4

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