Actelion’s efforts in drug discovery focus on the design, synthesis and optimization of small molecular weight molecules, which are active on molecular target families. This focus allows high productivity in the generation of innovative compounds potentially addressing a wide range of high unmet medical needs.

Initially, the company looked solely at G-protein coupled receptors (GPCRs) and a specific enzyme family known as aspartic proteinases. As the company’s capabilities have expanded, so too have the target platforms, adding anti-invective’s, ion channels and a broad range of soluble enzymes.

The productivity of Actelion’s drug discovery endeavors is demonstrated by the more than 3,800 pending patent applications and/or granted patents currently in Actelion’s portfolio, including 8 priority patent applications filed in 2016.



Actelion's research focuses on the design and synthesis of novel low molecular weight drug-like molecules. Experience has shown that small molecules generally lend themselves to easier formulation, have a broader array of dosage forms, have greater potential for bioavailability, in particular after oral administration, and are more efficiently manufactured. While Actelion’s medicinal chemistry and high-throughput chemistry groups synthesize smaller quantities of structurally diverse molecules, process research chemists prepare the quantities of selected compounds needed for further studies.


G-Protein coupled receptors (GPCRs), also known as seven transmembrane domain receptors (7TMs), are integral membrane proteins. They can be activated by external signals, such as hormones, neurotransmitters, or odors. This activation induces a conformational change of the receptor which in turn causes activation of G-proteins and the subsequent transmission of biochemical signals within the cell.

There are more than a hundred known GPCRs in humans, and many of them are involved in a broad range of diseases. Some of these receptors are the subject of our development programs, such as the endothelin receptors ETA and ETB, or the sphingosine-1-phosphate receptor S1P1.


Enzymes are proteins that catalyze chemical reactions and they are involved in almost all metabolic pathways in a living cell. The reactions enzymes speed-up  would often otherwise only occur at an infinitesimally small rate under physiological conditions. Enzymes are normally quiet specific for a given molecular substrate and are classified by the mechanism with  which they act on their substrate.

The aberrant activity of enzymes plays a role in many diseases and many well-known drugs are inhibitors of enzyme reactions. Actelion currently works on several different enzyme targets in its research programs, notably in oncology, fibrosis and anti-infectives. In the anti-infective field, Actelion medicinal chemists design compounds to target enzymes which are either radically different from those performing the same job in a human cell, or those enzymes that perform essential functions for the bacteria which don’t have a counterpart in human cells.


Due to the development of resistance to currently available antibiotics and the emergence of new pathogens, the medical need for new antibiotic compounds is high. In order to address this high unmet medical need, Actelion initiated, in 2004, a research program in the field of antibiotics. Actelion’s focus is on the discovery of novel classes of antibiotics that may offer improved properties, such as increased potency, coverage of multi-resistant pathogens, and a decreased inherent liability for resistance development. A portfolio of projects has been established focusing on both antibiotics for intravenous treatment of severe hospital infections, and oral antibiotics for community acquired infections.


Ion channels are transmembrane pores that allow the passage of ions (charged molecules) into or out of a cell. There are hundreds of different ion channels, distinguished by ion selectivity, opening mechanism, and protein sequence. Ion channels can be opened by chemical ligands, voltage fluctuations, acidity changes, temperature variations, or mechanical stimuli (e.g. touch or sound). Initially, Actelion established an in-house in-vitro electrophysiology group to provide internal support for early preclinical evaluation of drug safety in the area of cardiac electrophysiology. Since the scientific knowledge and technical capabilities required in this area are very similar to those in the area of cardiovascular ion channel therapies, research programs were soon initiated looking for modulators of selected ion channels to treat cardiovascular diseases. Expansion of the electrophysiology group and integration of new expertise and technologies led to the initiation of research projects targeting ion channels to treat neurological and immunological diseases.

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