An oral non-substrate-like DPP-4 inhibitor used for treating diabetes. dpp4 inhibitor, januvia, janumet, antidiabetic drug

Sitagliptin

Drug Name: 

Description Oral anti-diabetic drug
Target(s) Dipeptidyl peptidase-4 (DPP-4)
Generic Sitagliptin
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
IUPAC Name (2R)-4-oxo-4-[3-(trifluoromethyl)-5,6-dihydro[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl]-1-(2,4,5-trifluorophenyl)butan-2-amine
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)

Drug Information: 

Chemical Formula C16H15F6N5O
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

Drug Target: 

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). 

Drug-Target Complex: 

DPP-4 is a single polypeptide chain 766 residues in length, consisting of five regions:

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: 

Features Comment(s) Source
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
Absorption Site
Human intestine DrugBank
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.

Features Comment(s) Source
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

Regulatory Approvals/Commercial: 

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).

Links: 

DrugBank DB01261
Drugs.com https://www.drugs.com/mtm/sitagliptin.html
Food and Drugs Administration http://www.fda.gov/safety/medwatch/safetyinformation/safety-relateddruglabelingchanges/ucm121926.htm
Liver Tox: National Institutes of Health (NIH)
http://livertox.nlm.nih.gov//Sitagliptin.htm

Table 5. Links to Relevant Resources

References: 

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.

Drugs.com. https://www.drugs.com/.

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, Doubleblind, Placebocontrolled 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