TCS-OX2-29 is a drug which was the first non-peptide antagonist developed that is selective for the orexin receptor

Orexin receptor

The orexin receptor is a G-protein-coupled receptor that binds the neuropeptide hormone orexin. There are two variants, OX1 and OX2, each encoded by a different gene .-External links:...

 subtype OX₂

Hypocretin (orexin) receptor 2

Orexin receptor type 2 , also known as hypocretin receptor type 2, is a protein that in humans is encoded by the HCRTR2 gene.- Function :...

, with an IC₅₀ of 40nM and selectivity of around 250x for OX₂ over OX₁

Hypocretin (orexin) receptor 1

Orexin receptor type 1 , also known as hypocretin receptor type 1, is a protein that in humans is encoded by the HCRTR1 gene.- Function :...

 receptors. Orexin antagonists are expected to be useful for the treatment of insomnia

Insomnia

Insomnia is most often defined by an individual's report of sleeping difficulties. While the term is sometimes used in sleep literature to describe a disorder demonstrated by polysomnographic evidence of disturbed sleep, insomnia is often defined as a positive response to either of two questions:...

, with subtype-selective antagonists such as TCS-OX2-29 potentially offering more specificity of action compared to non-selective orexin antagonists like almorexant

Almorexant

Almorexant is a competitive receptor antagonist of the OX1 and OX2 orexin receptors, which was being developed by the pharmaceutical companies Actelion and GSK for the treatment of insomnia...

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