|Description||Oral anti-diabetic drug|
|Target(s)||Dipeptidyl peptidase-4 (DPP-4)|
|Commercial Name||Januvia (United States, United Kingdom, Canada)|
|Combination Drug(s)||Janumet, Janumet XR* (sitagliptin & metformin)|
|Other Synonyms||Sitagliptan, Sitagliptin phosphate, Sitaglipina, Sitagliptine, Sitagliptum, MK-0431|
|Ligand Code in PDB||715|
|3D Structure of Sitagliptin bound to target protein DPP-4||PDB ID 1x70|
*Janumet extended-release (XR)
Table 1. Basic Profile of Sitagliptin
Figure 1. 2D Structure of Sitagliptin (PubChem)
|Molecular Weight||407.31 g/mol|
|Calculated Predicted Partition Coefficient: cLogP||1.5|
|Calculated Predicted Aqueous Solubility: cLogS||-4.1|
|Solubility (in water)||0.034 mg/mL (sparingly soluble)|
|Predicted Topological Polar Surface Area (TPSA)||77.04 Å2|
Sitagliptin is an orally active, non-substrate-like DPP-4 inhibitor. By blocking DPP-4 enzymatic activity, sitagliptin increases the half-life of incretin hormones, GLP-1 and GIP, which are released by the endocrine cells in the gastrointestinal tract in response to food intake (Ahrén, 2002). GLP-1 and GIP stimulate increased secretion of insulin by pancreatic β-cells and reduced secretion of glucagon by pancreatic α-cells, thereby lowering blood glucose levels. Since incretins are only released by the small intestine after eating, DPP-4 inhibitors do not induce hypoglycemia (Aschner, 2006).
DPP-4 is a single polypeptide chain 766 residues in length, consisting of five regions:
- a cytoplasmic region (residues 1–6) not crystallized/not shown
- a trans-membrane region (residues 7–28) not crystallized/not shown
- a highly glycosylated region (residues 29–323) colored cyan
- a cysteine-rich region (residues 324–551) colored pink
- a catalytic region (residues 552–766) colored orange
Figure 2. Overall structure of human DPP-4 monomer in ribbon representation showing the N- and C-termini and color-coded regions labeled, including cysteine-rich region (pink), the highly glycosylated region (cyan) and the catalytic domain (orange). Sitagliptin is shown in a ball and stick representation in the figure. (PDB ID 1x70; Kim et al., 2005).
Figure 3. X-ray crystal structure of the DPP-4 dimer (ribbons), with bound Sitagliptin (ball-and-stick). The DPP-4 monomer on the right is color-coded by region as in Figure 2 and the monomer on the left is shown as a grey ribbon. (PDB ID 1x70; Kim et al., 2005). Surface of the active site of DPP-4 is shown in the inset. Sitagliptin is shown in ball and stick figure, color-coded by atom type (C: gray; N: blue; O: red; F: green). Selected residues in the active sites are shown as stick figures.
The black boxed region in the structure of Sitagliptin bound to DPP-4 (Figure 3), denotes the location of the active site. Figure 4 shows a close-up view of sitagliptin in the active site. The aromatic moieties within the drug occupy the S1 and S2 pockets of the enzyme. The trifluoromethyl group of the drug occupies the S2 extensive site.
Figure 4. Hydrogen Bonding interactions (green lines) between Sitagliptin (ball and stick) and active site residues (stick figure). (PDB ID 1x70; Kim et al., 2005).
Figure 5. Hydrogen Bonding interactions (green lines) between Diprotin A (ball and stick) and active site residues (stick figure). (PDB ID 1nu8; Thoma et al., 2003).
Sitagliptin makes extensive hydrogen bonding interactions (represented as green lines) with the residues lining the enzyme active site, as does Diprotin-A (Ile-Pro-Ile, a DPP-4 substrate). Comparison of the co-crystal structures of DPP-4 with Sitagliptin (PDB ID 1x70, Figure 4) and Diprotin A with DPP-4 (PDB ID 1nu8, Figure 5) reveals that Sitagliptin acts by occluding the DPP-4 active site and prevents binding of incretin hormones.
Pharmacologic Properties and Safety:
|Oral Bioavailability (%)||87%||Capuano et al., 2013|
|IC50 (nM)||18 nM||Green et al., 2007|
|Ki (nM)||9 nM||Green et al., 2007|
|Half-life (hrs)||8-14 hours||Capuano et al., 2013|
|Duration of Action||N/A||N/A|
|Transporter(s)||Multidrug resistance protein 1||DrugBank|
|Metabolism||Cytochrome p450 3A4 and 2C8||DrugBank|
|Excretion||~87% urine; ~13% feces||Capuano et al., 2013|
|AMES Test (Carcinogenic Effect)||0.5487 (non AMES toxic)||DrugBank|
|hERG Safety Test (Cardiac Effect)||probability 0.7076 (weak inhibitor)||DrugBank|
|Liver Toxicity||Liver injury due to sitagliptin is rare. A single case report of clinically apparent liver injury has been published in a patient who also had hepatitis C.||LiverTox|
Table 3. Pharmacokinetics: ADMET of Sitagliptin
Drug Interactions and Side Effects:
Although hypoglycemia is rarely observed with Sitagliptin as monotherapy (<1%), it does occur more frequently when combined with other oral hypoglycemic agents. Dosage reduction(s) may be recommended for concomitant administration of Sitagliptin with other antidiabetic treatments.
|Total Number of Drug Interactions||642 drugs||Drugs.com|
|Major Drug Interactions||bexarotene and gatifloxacin||Drugs.com|
|Alcohol/Food Interaction(s)||moderate interaction with alcohol (ethanol)||Drugs.com|
|On-target Side Effects||nausea, diarrhea, vomiting, flatulence, abdominal Pain, pancreatitis, renal complications||Drugs.com|
|Off-target Side Effects||headaches, drowsiness, weakness, joint pain, allergic reaction, upper respiratory infection||Drugs.com|
Table 4. Drug Interactions and Side Effects of Sitagliptin
Developed by Merck & Co. and approved by the US FDA in 2006, Januvia (sitagliptin) is prescribed as an oral monotherapy in 25 mg, 50 mg, or 100 mg doses and is usually taken once a day. Sitagliptin underwent two double-blind, randomized, and placebo-controlled clinical trials in the U.S. (Herman, 2005). Merck & Co. has also developed a fixed dose Sitagliptin/Metformin combination, under the name Janumet and Janumet XR®. The cost of a 30-day supply of 100 mg tablets of Sitagliptin is about US $350 (or US $12/day).
|Food and Drugs Administration||http://www.fda.gov/safety/medwatch/safetyinformation/safety-relateddruglabelingchanges/ucm121926.htm|
|Liver Tox: National Institutes of Health (NIH)
Table 5. Links to Relevant Resources
Aertgeerts, K., Ye S., Tennant, M.G., Kraus, M.L., Rogers, J., Sang, B.C., Skene, R.J., Webb, D.R., Prasad, G.S. (2004). Crystal Structure of Human Dipeptidyl Peptidase IV in Complex with a Decapeptide reveals Details on Substrate Specificity and Tetrahedral Intermediate Formation. Protein Science, 13(2), 412-421. doi: 10.1110/ps.03460604
Ahrén, B., Simonsson, E., Larsson, H., Landin-Olsson, M., Torgeirsson, H., Jansson, P.A., Sandqvist, M., Båvenholm, P., Efendic, S., Eriksson, J.W., Dickinson, S., Holmes, D. (2002). Inhibition of Dipeptidyl Peptidase IV Improves Metabolic Control Over a 4-week Study Period in Type 2 Diabetes. Diabetes Care, 25(5), 869-875. doi: 10.2337/diacare.25.5.869
American Diabetes Association. (2013). Economic costs of diabetes in the US in 2012. Diabetes Care, 36(4), 1033-46. doi: 10.2337/dc12-2625
Aschner, P., Kipnes, M.S., Lunceford, J.K., Sanchez, M., Mickel, C., Williams-Herman, D.E.(2006). Effect of the Dipeptidyl Peptidase-4 Inhibitor Sitagliptin as Monotherapy on Glycemic Control in Patients with Type 2 Diabetes. Diabetes Care, 29(12), 2632-37. doi: 10.2337/dc06-0703
Capuano, A. et al. (2013). Dipeptidyl Peptidase-4 Inhibitors in Type 2 Diabetes Therapy – Focus on Alogliptin". Drug, Design, Development and Therapy, 213(7), 989-1001 doi: 10.2147/DDDT.S37647
Diabetes, W. H. O. (2016). Fact sheet Reviewed Nov 2016 http://www.who.int/mediacentre/factsheets/fs312/en/
DrugBank: Sitagliptin. (2007). http://www.drugbank.ca/drugs/DB01261.
Gadsby, R. (2009) Efficacy and Safety of Sitagliptin in the Treatment of Type 2 Diabetes. Clinical Medicine: Therapeutics 1, 53–62, Retrieved from here
Green, B., Flatt, P., and Bailey, C. (2007) Gliptins: DPP-4 Inhibitors to Treat Type 2 Diabetes. Future Prescriber, 8(3), 6-12. doi: 10.1002/fps.33
Herman, G. A. et al. (2005) Pharmacokinetics and Pharmacodynamics of Sitagliptin, an Inhibitor of Dipeptidyl Peptidase IV, in Healthy Subjects: Results from Two Randomized, Double‐blind, Placebo‐controlled Studies with Single Oral Doses. Clinical Pharmacology & Therapeutics, 78(6), 675-88. doi: 10.1016/j.clpt.2005.09.002
Januvia. (n.d.). http://www.goodrx.com/januvia
Kim, D. et al. (2005) (2 R)-4-Oxo-4-[3-(trifluoromethyl)-5, 6-dihydro [1, 2, 4] triazolo [4, 3-a] pyrazin-7 (8 H)-yl]-1-(2, 4, 5-trifluorophenyl) butan-2-amine: a Potent, Orally Active Dipeptidyl Peptidase IV Inhibitor for the Treatment of Type 2 Diabetes. Journal of Medicinal Chemistry, 48(1), 141-151. doi: 10.1021/jm0493156
Sitagliptin (Januvia). (2008) http://www.glucagon.com/sitagliptin.html
Thoma, R., Loffler, B., Stihle, M., Huber, W., Ruf, A., Hennig, M. (2003) Structural basis of proline-specific exopeptidase activity as observed in human dipeptidyl peptidase-IV. Structure. 11(8), 947-959. doi: 10.1016/S0969-2126(03)00160-6
Summer 2016, Peter T. Davis, Jennifer Jiang, Sutapa Ghosh; Reviewed by Drs. John Kozarich and Stephen K. Burley