Carmoterol Hydrochloride

G-protein-coupled receptors (GPCRs) mediate multiple signaling pathways in the cell, depending on the agonist that activates the receptor and multiple cellular factors. Agonists that show higher potency to specific signaling pathways over others are known as "biased agonists" and have been shown to have better therapeutic index. Although biased agonists are desirable, their design poses several challenges to date. The number of assays to identify biased agonists seems expensive and tedious. Therefore, computational methods that can reliably calculate the possible bias of various ligands ahead of experiments and provide guidance, will be both cost and time effective. In this work, using the mechanism of allosteric communication from the extracellular region to the intracellular transducer protein coupling region in GPCRs, we have developed a computational method to calculate ligand bias ahead of experiments. We have validated the method for several β-arrestin-biased agonists in β₂-adrenergic receptor (β2AR), serotonin receptors 5-HT1B and 5-HT2B and for G-protein-biased agonists in the κ-opioid receptor. Using this computational method, we also performed a blind prediction followed by experimental testing and showed that the agonist carmoterol is β-arrestin-biased in β2AR. Additionally, we have identified amino acid residues in the biased agonist binding site in both β2AR and κ-opioid receptors that are involved in potentiating the ligand bias. We call these residues functional hotspots, and they can be used to derive pharmacophores to design biased agonists in GPCRs.

Inhaled bronchodilators, including long-acting muscarinic receptor antagonists (LAMA) and long-acting β2-adrenoreceptor agonists (LABA), are the mainstay of pharmacological treatment of stable chronic obstructive pulmonary disease (COPD). Among approved LAMA, tiotropium bromide, glycopyrronium bromide, and umeclidinium bromide are administered once daily, whereas aclidinium bromide is administered every 12 h. New LAMA are under development for COPD. Among the approved LABA, indacaterol has a 24 h duration of action, whereas salmeterol and formoterol require twice-daily administration. New once-daily LABA, including vilanterol, olodaterol, milveterol, carmoterol, and abediterol, are in development. LAMA/LABA fixed dose combinations (FDCs) provide the convenience of two bronchodilators with different mechanism of action in a single inhaler. Indacaterol/glycopyrronium, umeclidinium/vilanterol, and olodaterol/tiotropium FDCs have been approved or are under approval and are likely to become a standard pharmacological strategy for COPD. Inhaled dual-pharmacology compounds, combining muscarinic antagonism and β2-agonism (MABA) in a single molecule, potentially provide additive or synergistic bronchodilation over either inhaled antimuscarinic or β2-agonist monotherapy.