Semaglutide

Semaglutide is a long acting GLP-1R agonist that is administered subcutaneously, as a treatment of type 2 diabetes. Developed by Novo Nordisk it was approved by the US FDA in 2017. Sharing a 94% structural homology with native human GLP-1, Semaglutide is distinguished by three modifications: 1) amino-acid substitutions at position 8 (alanine to α-aminoisobutyric acid or Aib) and position 34 (lysine to arginine), and acylation of the lysine in position 26 with a spacer consisting of two 8-amino-3,6-dioxaoctanoic acid (ADO) moieties, a glutamic acid moiety, and a C-18 fatty di-acid side chain (Lau et al., 2015).

Table 1. Basic Profile of Semaglutide

Figure 1. 2D and 3D structures of Semaglutide. a. The amino acid sequence of Semaglutide (PubChem) is numbered from 7 to 37. The sequence schematic shown is based on information presented in Knudsen and Lau, 2019. Amino acid modifications are highlighted in yellow and the DPP4 cleave site is indicated with the scissors. b. 3D structure of Semaglutide (PDB ID 7ki0, Zhang et al., 2021). Note: The C-18 fatty acyl chain shown here is partially disordered. Only atoms included in the structures are shown here. The receptor and G-protein chains are hidden here for clarity. Click here to view the full structure interactively.

Drug Information

Table 2. Chemical and physical properties of Semaglutide

Drug Target

Semaglutide was developed as an oral or an injectable drug product.

The addition of the C-18 fatty acid moiety to Lys26 is hypothesized to increase the binding dose-response ratio due to an increased albumin affinity. The replacement of Ala8 with Aib did not significantly change the binding affinity, but did result in a decline in potency as a substrate for DPP4. Collectively, these modifications prolong the half-life of semaglutide to approximately 1 week, or 165 hours (Lau et al., 2015). The mechanism of action is the same as GLP-1, including stimulation of insulin secretion, slowing gastric emptying, and reducing postprandial glucagon secretion in a glucose-dependent fashion.

The first generation of GLP-1 therapies exhibit reduced susceptibility to enzymatic degradation, while providing effective glucose control, improved β-cell function, body weight loss and decreased systolic blood pressure in patients with T2D (Meier, 2012) The newly developed incretin mimetics, including albiglutide, dulaglutide and semaglutide, are designed to have extended pharmacokinetic profiles and efficacy suitable once-weekly administration.

Drug Target Complex

Belonging to the class B G-protein-coupled receptor, GLP-1R is a seven-transmembrane protein receptor (Figure 2). It consisting of:

• An extracellular N-terminus that binds the C-terminal part of the incretin analog
• A seven transmembrane helical domain (TMD) with the a-helices separated by three intracellular loops and three extracellular loops
• An intracellular C-terminus that is responsible for signaling

The EM structure of Semaglutide bound to the complete GLP-1R and G-proteins (Figure 2, PDB ID 7ki0, Zhang et al., 2021) shows some hydrophobic and many specific polar interactions between the peptidic drug and the GLP-1 receptor molecule. At the N-terminus, the His7 of Semaglutide forms a direct hydrogen bond with the side chain of Gln234 and a water mediated hydrogen bond with Tyr241 of the receptor. The Glu9 forms an ionic bond with Arg190 and a hydrogen bond with Tyr152. The Thr13 forms a hydrogen bond with Tyr197, while Asp15 forms an ionic bond with R299. The Ser14 and Ser17 of Semaglutide form a network of hydrogen bonds involving the receptor residues Asn300, Arg299, and Thr298. The Tyr19 of Semaglutide forms a hydrogen bond with Glu138 of the receptor and Gln17 of the peptide, while Glu21 of Semaglutide forms a hydrogen bond with Ser31 and an ionic bond with Arg299 of the receptor. Hydrogen bonds between the backbone atoms of Val33 of Semaglutide (with the receptors Arg121) and the ionic bonds between Semaglutide’s Arg36 and the receptor’s Glu68, contribute to stably binding the C-terminal portion of the Semaglutide peptide.

While several of the interactions listed here are common to those seen between GLP-1 and its receptor, overall there appears to be many more specific polar interactions between Semaglutide and the GLP-1 receptor. These may play a key role in the high increased half life of the Semaglutide-GLP-1R complex (165+ hours, compared to the ~13 hours in the case of Liraglutide).

Figure 2. EM structure of GLP-1R (red) with bound Semaglutide (gold) (PDB ID 7ki0, Zhang et a., 2021). Location of the membrane, and G-proteins associated with the receptor are also shown. The insets show a close up of specific polar interactions between the Semaglutide and the GLP-1R.

Pharmacologic Properties

Table 3. Pharmacokinetics: ADMET of Semaglutide

Drug Interactions and Side Effects

Table 4. Drug interactions and side effects of Semaglutide

In studying the effects of semaglutide treatment on the pharmacokinetics metformin, warfarin, atorvastatin and digoxin, it was found that this GLP-1 analog did not affect such properties to a clinically relevant degree (Hausner et al., 2017). Therefore, these drugs can be administered concomitantly with semaglutide without dose adjustment. However, since semaglutide impacts gastric emptying, the dosage of any other drugs taken concomitantly should be appropriately monitored by health care providers.

Regulatory Approvals/Commercial

Semaglutide is a GLP-1 analog, developed in 2012 by Novo Nordisk, as a longer acting alternative to liraglutide. The US FDA approved an injectable version (brand name Ozempic) as an anti-diabetes treatment in the United States in 2017 and in the rest of the world in 2018.

In 2019 and 2020, a formulation of Semaglutide (brand name Rybelsus) was approved as a daily oral medication for treating diabetes, when used along with diet and exercise. In 2022 this medication was approved as a first-line treatment for diabetes.

In 2021 - 2022, a stronger dose, weekly injectable formulation of Semaglutide (brand name Wegovy) was approved by the US FDA as a medication for weight loss in patients with at least one weight related medical issue.

In 2023, the high demand and possible off-label of this medication to treat obesity led to supply shortages of Wegovy.

Although Semaglutide is shown to be effective in lowering weight, HbA1c levels, and reducing cardiovascular risk, there are many side effects of this medication that should be closely monitored. The medication may have an impact on embryo and fetal development (US FDA package insert).

Links

Table 5. Links to Relevant Resources

References

Dalsgaard, N.B., Brønden, A., Vilsbøll, T., Knop, F.K. (2017) Cardiovascular safety and benefits of GLP-1 receptor agonists. Expert Opin Drug Saf.16, 351-363. https://doi.org/10.1080/14740338.2017.1281246

Hausner, H., Derving Karsbøl, J., Holst, A.G., Jacobsen, J.B., Wagner, F.D., Golor, G., Anderson, T.W. (2017) Effect of Semaglutide on the Pharmacokinetics of Metformin, Warfarin, Atorvastatin and Digoxin in Healthy Subjects. Clin Pharmacokinet. 56, 1391-1401. https://doi.org/10.1007/s40262-017-0532-6

Jensen, L., Helleberg, H., Roffel, A., van Lier, J.J., Bjørnsdottir, I., Pedersen, P.J., Rowe, E., Derving Karsbøl, J., Pedersen, M.L. (2017) Absorption, metabolism and excretion of the GLP-1 analogue semaglutide in humans and nonclinical species. Eur J Pharm Sci. 104, 31-41. https://doi.org/10.1016/j.ejps.2017.03.020

Kapitza, C., Nosek, L., Jensen, L., Hartvig, H., Jensen, C.B., and Flint A. (2015). Semaglutide, a Once-Weekly Human GLP-1 Analog, does not reduce the Bioavailability of the Combined Oral Contraceptive, Ethinylestradiol/Levonorgestrel. Journal of Clinical Pharmacology, 55(5): 497-504. https://doi.org/10.1002/jcph.443.

Knudsen, L.B., Lau, J. (2019) The Discovery and Development of Liraglutide and Semaglutide. Front Endocrinol (Lausanne). 10, 155. https://doi.org/10.3389/fendo.2019.00155

Lau, J., Bloch, P., Schäffer, L., Pettersson, I., Spetzler, J., Kofoed, J., Madsen, K., Knudsen, L.B., McGuire, J., Steensgaard, D.B., Strauss, H.M., Gram, D.X., Knudsen, S.M., Nielsen, F.S., Thygesen, P., Reedtz-Runge, S., and Kruse, T., (2015), Discovery of the Once-Weekly Glucagon-Like Peptide-1 (GLP-1) Analogue Semaglutide, Journal of Medicinal Chemistry 58, 7370-7380. https://doi.org/10.1021/acs.jmedchem.5b00726.

Marso, S.P., Bain, S.C., Consoli, A., Eliaschewitz, F.G., Jódar, E., Leiter, L.A., Lingvay, I., Rosenstock, J., Seufert, J., Warren, M.L., Woo, V., Hansen, O., Holst, A.G., Pettersson, J., Vilsbøll, T. (2016) SUSTAIN-6 Investigators. Semaglutide and Cardiovascular Outcomes in Patients with Type 2 Diabetes. N Engl J Med. 375, 1834-1844. https://doi.org/10.1056/nejmoa1607141

Meier, J.J. (2012). GLP-1 receptor Agonists for Individualized Treatment of Type 2 Diabetes Mellitus. Nature Reviews Endocrinology, 8, 728-42. https://doi.org/10.1038/nrendo.2012.140

Zhang, X., Belousoff, M.J., Liang, Y.L., Danev, R., Sexton, P.M., Wootten, D. (2021) Structure and dynamics of semaglutide- and taspoglutide-bound GLP-1R-Gs complexes. Cell Rep. 36, 109374. https://doi.org/10.1016/j.celrep.2021.109374

August 2023 Jennifer Jiang and Dr. Shuchismita Dutta; Reviewed by Dr. Joseph D. Ho
http://dx.doi.org/10.2210/rcsb_pdb/GH/DM/drugs/in/Semaglutide