Vildagliptin

Table 1. Basic profile of vildagliptin

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Table 2. Chemical and physical properties (DrugBank).

*Note: Predicted values may slightly vary from source to source. 

Vildagliptin is an orally active, antidiabetic drug that works by inhibiting the enzyme dipeptidyl peptidase-4 (DPP-4) (Villhauer et al., 2003). In response to food intake, endocrine cells in the gastrointestinal tract release incretin hormones, GLP-1 and GIP, to stimulate insulin secretion. Normally, DPP-4 degrades the incretin hormones within a few minutes of their release, thereby playing a key role in regulating the duration of incretin hormone function. By blocking DPP-4 enzymatic activity, vildagliptin increases the half-life of the incretin hormones, which in turn stimulates increased secretion of insulin by pancreatic β-cells and reduces secretion of glucagon by pancreatic α-cells. Collectively, these functions lower blood glucose levels. Since the incretins, GLP-1 and GIP, are only released after eating, DPP-4 inhibitors typically do not induce hypoglycemia (Aschner et al., 2006).

Learn more about DPP-4 here.

Each molecule of the DPP-4 enzyme is a transmembrane glycoprotein made up of 766 amino acids and consists 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

The overall structure of the extracellular portion of the enzyme, showing the highly glycosylated, cysteine-rich, and catalytic regions can be seen in Figure 2.

Figure 2. Overall structure of human DPP-4 monomer in complex with vildagliptin. The enzyme is shown in ribbon representation, highlighting the N- and C-termini and various regions of the protein - cysteine-rich region (pink), highly glycosylated region (cyan) and catalytic domain (orange). Vildagliptin is shown in ball-and-stick representation (PDB ID: 3w2t; Nabeno et al., 2013).

The DPP-4 enzyme functions as a dimer, composed of two copies of the same protein (Figure 3). Vildagliptin is a substrate-like inhibitor of DPP-4 and forms a covalent complex with the enzyme. This class of compounds interacts covalently with the catalytically active serine hydroxyl (Ser630) and has a proline-like group that occupies the S1 pocket of the active site.

Figure 3. X-ray crystal structure of the DPP-4 dimer (ribbons) with bound vildagliptin (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: 3w2t; Nabeno et al., 2013). Vildagliptin is shown in a ball-and-stick representation, color-coded by atom type (C: gray; N: blue; O: red). Selected residues in the active sites are shown as stick figures.

Closer examination of the co-crystal structure of DPP-4 and vildagliptin (PDB entry 3w2t, Nabeno et al., 2013) reveals multiple interactions of the drug with its pharmacological target, DPP-4 (Figure 4). The cyanopyrrolidine binds to the S1 subsite - the nitrile group from the cyanopyrrolidine ring forms the covalent imidate adduct with the hydroxyl of Ser630 in the catalytic triad; the cyanopyrrolidine ring itself is buried in the S1 subsite of DPP-4 active site (Figure 4). The drug also forms several hydrogen bonds - the carbonyl oxygen of vildagliptin forms a hydrogen bond with Asn710; the amino group of the drug participates in hydrogen-bonding with Glu205 and Glu206; and the nitrogen of the cyanopyrrolidine rings interacts with the side-chain hydroxyl of Tyr547 (Nabeno et al., 2013). Together these interactions account for the tight binding of the drug.

Figure 4. Hydrogen bonding interactions (green lines) between vildagliptin (ball-and-stick) and active site residues (stick figures) (PDB ID: 3w2t; Nabeno et al., 2013).	Figure 5. Hydrogen bonding interactions (green lines) between Diprotin A (ball-and-stick) and active site residues (stick figures) (PDB ID: 1nu8; Thoma et al., 2003).

A comparison of the co-crystal structures of DPP-4 with vildagliptin (PDB ID 3w2t, Figure 4) and DPP-4 with its substrate, Diprotin A (Ile-Pro-Ile), (PDB ID 1nu8, Figure 5) reveals that vildagliptin acts by occluding the DPP-4 active site and prevents binding of incretin hormones.

Table 3. Pharmacokinetics: ADMET of vildagliptin

*Interestingly, while vildagliptin-induced hepatotoxicity is uncommon in patients, studies in rats indicate that vildagliptin may protect the liver from cyclosporine-induced hepatotoxicity via reduction of DPP-4 activity and oxidative stress (El-Sherbeeny et al., 2015)

Following oral administration of vildagliptin, approximately 85.4% of the drug is absorbed, only a small amount (4.54%) of unchanged drug in excreted via feces (He et al., 2009). The absorbed drug is metabolized in multiple ways - a carboxylic acid product, resulting from the cyano group hydrolysis, is a major metabolite. Since the drug metabolism does not involve the cytochrome P450 system, vildgaliptin has a low drug-drug interaction profile when coadministered with P450 inhibitors/inducers.

Vildagliptin does not display any harmful effects on cardiac health nor is it carcinogenic (DrugBank).  Meta-analyses suggest that vildagliptin is not associated with in drug-caused liver injury, pancreatitis, infection, elevated hepatic enzyme levels, skin-related toxicity, and an increased risk of hepatic related injury (Ligueros-Saylan et al., 2010).
There is no known interaction between vildagliptin and cytochrome p450 3A4. In combination with metformin, sulfonylurea, thiazolidinedione, and rosiglitazone, the steady-state pharmacokinetics of vildagliptin were unaltered and no adverse side-effects of using vildagliptin in combination with other drugs including amlodipine, ramipril, valsartan and simvastatin (Novartis 2015).

Table 4. Drug interactions and side effects of vildagliptin

Galvus (vildagliptin) was developed by Novartis. It is currently approved for use by European Medicines Agency (2008) for use within the EU, and is available in many countries. However, it has not been approved by the US FDA. Patients diagnosed with type 2 diabetes mellitus take Galvus once a day in 100 mg doses or twice daily in 50 mg doses (Novartis 2015).  Galvus tablets are to be administered orally with a glass of water and can be taken as monotherapy or as an add-on drug. 60 tablets sell for approximately $97.24, which comes out to roughly $1.62 per tablet (Novartis 2015).

Table 5. Links to relevant resources

Aschner, P., Kipnes, M. S., Lunceford, J. K., Sanchez, M., Mickel, C., and 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, 2632-2637. doi: 10.2337/dc06-0703

Capuano, A., Sportiello, L., Maiorino, M. I., Rossi, F., Giugliano, D., and Esposito, K. (2013) Dipeptidyl Peptidase-4 Inhibitors in Type 2 Diabetes Therapy – Focus on Alogliptin. Drug, Design, Development and Therapy 213, 989-1001. doi: 10.2147/DDDT.S37647

El-Sherbeeny, N. A., and Nader M. A. (2015) The Protective Effect of Vildagliptin in Chronic Experimental Cyclosporine A-induced Hepatotoxicity. Canadian Journal of Physiology and Pharmacology 94, 251-256. doi: 10.1139/cjpp-2015-0336

Galvus (vildagliptin). Guidelink.com. www.guildlink.com.au/gc/ws/nv/pi.cfm?product=nvpgalor10216 

He, H., Tran, P., Yin, H., Smith, H., Flood, D., Kramp, R., Filipeck, R., Fischer, V., and Howard, D. (2009) Absorption, metabolism, and excretion of [14C]vildagliptin, a novel dipeptidyl peptidase 4 inhibitor, in humans. Drug Metabolism and Disposition 37, 536-544. doi:10.1124/dmd.108.023010

Ligueros-Saylan, M., Foley, J. E., Schweizer, A., Couturier, A., and Kothny, W. (2010) An Assessment of Adverse Effects of Vildagliptin versus Comparators on the Liver, the Pancreas, the Immune system, the Skin and in Patients with Impaired Renal Function from a Large Pooled Database of Phase II and III Clinical Trials. Diabetes, Obesity and Metabolism 12, 495-509. doi: 10.1111/j.1463-1326.2010.01214.x

Nabeno, M. Akahoshi, F., Kishida, H., Miyaguchi, I., Tanaka, Y., Ishii, S., and Kadowaki, T. (2013) A Comparative Study of the Binding Modes of Recently Launched Dipeptidyl Peptidase IV Inhibitors in the Active Site. Biochemical and Biophysical Research Communications 434, 191-196. doi: 10.1016/j.bbrc.2013.03.010

Thoma, R., Loffler, B., Stihle, M., Huber, W., Ruf, A., and Hennig, M. (2003) Structural basis of proline-specific exopeptidase activity as observed in human dipeptidyl peptidase-IV. Structure 11, 947-959.  doi: 10.1016/S0969-2126(03)00160-6

Thomas, L., Eckhardt, M., Langkopf, E., Tadayyon, M., Himmelsbach, F., and Mark, M. (2008) (R)-8-(3-Amino-Piperidin-1-Yl)-7-But-2-Ynyl-3-Methyl-1-(4-Methyl-Quinazolin-2-Ylmethyl)-3,7-Dihydro-Purine-2,6-Dione (BI 1356), a Novel Xanthine-Based Dipeptidyl Peptidase 4 Inhibitor, has a Superior Potency and Longer Duration of Action Compared with Other Dipeptidyl Peptidase-4 Inhibitors. Journal of Pharmacology and Experimental Therapeutics 325, 175-182. doi: 10.1124/jpet.107.135723

Vildagliptin. Drugbank.ca. http://www.drugbank.ca/drugs/DB04876

Vildagliptin. Pubchem.ncbi.nlm.nih.gov. https://pubchem.ncbi.nlm.nih.gov/compound/Vildagliptin

Vildagliptin. - Affinity Data by PDB ID. Bindingdb.org. http://www.bindingdb.org/jsp/dbsearch/PrimarySearch_pdbids.jsp?pdbids_submit=Search&pdbids=3W2T

Villhauer, E. B., Brinkman, J. A., Naderi, G. B., Burkey, B. F., Dunning, B. E., Prasad, K., Mangold, B. L., Russell, M. E., and Hughes, T. E. (2003) 1-[[(3-hydroxy-1-adamantyl)amino]acetyl]-2-cyano-(S)-pyrrolidine: a potent, selective, and orally bioavailable dipeptidyl peptidase IV inhibitor with antihyperglycemic properties. Journal of Medicinal Chemistry 46, 2774-2789. doi: 10.1021/jm030091l