Selective Ligands
Several drugs acting on the orexin system are under development, either orexin agonists for the treatment of conditions such as narcolepsy, or orexin antagonists for insomnia. No non-peptide agonists are yet available, although synthetic Orexin-A polypeptide has been made available as a nasal spray and tested on monkeys. Several non-peptide antagonists are in development however; SB-649,868 is under development by GlaxoSmithKline for sleep disorders and is a non-selective orexin receptor antagonist. Another OX1 and OX2 receptor antagonist (ACT-078573, almorexant) is a similar compound under development for primary insomnia by Actelion. A third entry is Merck's MK-4305.
Most ligands acting on the orexin system so far are polypeptides modified from the endogenous agonists Orexin-A and Orexin-B, however there are some subtype-selective non-peptide antagonists available for research purposes.
- SB-334,867 - selective OX1 antagonist
- SB-408,124 - selective OX1 antagonist
- TCS-OX2-29 - selective OX2 antagonist
- EMPA(drug) (N-Ethyl-2--N-pyridin-3-ylmethyl-acetamide) - selective OX2 antagonist
Read more about this topic: Orexin
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“The selective memory isn’t selective enough.”
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