An oral xanthine based DPP-4 inhibitor used for treating diabetes. dpp4 inhibitor, tradjenta, antidiabetic drug



Oral anti-diabetic drug


Dipeptidyl peptidase-4 (DPP-4)



Commercial Name

Tradjenta (United States, Canada)

Combination Drug(s)

Glyxambi (linagliptin & empagliflozin)

Other Synonyms

BI-1356, Ondero



Ligand Code in PDB


3D Structure of linagliptin bound to target protein DPP-4

PDB ID 2rgu

Table 1.  Basic profile of linagliptin

Figure 1. 2D Structure of Linagliptin

2D and 3D structure of linagliptin.

Drug Information: 

Chemical Formula


Molecular Weight

472.23 g/mol

Calculated Predicted Partition Coefficient: cLogP


Calculated Predicted Aqueous Solubility: cLogS


Solubility (in water)

0.0502 mg/mL (sparingly soluble)

Predicted Topological Polar Surface Area (TPSA)

113.48 Å2

Table 2. Chemical and physical properties (DrugBank).

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

Drug Target: 

Like the other gliptins, linagliptin competitively inhibits DPP-4, the enzyme responsible for the degradation of incretins GLP-1 and GIP. Inactivation of DPP-4 potentiates the incretin effect, during which GLP-1 and GIP stimulate increased insulin secretion and suppress glucagon release. Overall, the suppression of glucose production in the liver and increased concentration of insulin in the blood result in lower blood glucose levels. Linagliptin has been structurally derived from the xanthine scaffold (Deacon et al. 2010). It is a highly potent, selective and long-acting hypoglycemic agent that exhibits considerable blood glucose lowering effects (Eckhardt et al., 2007). Unlike the other DPP-4 inhibitor drugs, linagliptin has a non-linear pharmacokinetic profile (Prabavathy, 2011) and is not primarily eliminated by the renal system (DrugBank).

Drug-Target Complex: 

DPP-4 is a transmembrane glycoprotein made up of 766 amino acids and consists 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). Linagliptin is shown as a ball-and-stick representation (PDB ID: 2rgu; Eckhardt et al., 2007).

Linagliptin is a non-substrate-like inhibitor of DPP-4. This class of DPP-4 inhibitors does not mimic the dipeptidic nature of the DPP-4 substrates. Instead, it binds non-covalently to DPP-4 through hydrophobic and hydrogen-bonding interactions, and an aromatic group usually occupies the S1 hydrophobic sub-pocket of the active site of DPP-4.

Figure 3. X-ray crystal structure of the DPP-4 dimer (ribbons), with bound linagliptin (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: 2rgu; Eckhardt et al., 2007). The surface of the active site of DPP-4 is shown in the inset. Linagliptin 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 in the stick representation.

The X-ray structure of DPP-4 bound to linagliptin (PDB entry 2rgu) is shown in Figure 3. The black box denotes the location of the active site. The figure at the bottom right shows a close-up view of linagliptin (ball-and-stick) in the active site (grey surface).

Figure 4. Hydrogen bonding interactions (green lines) between linagliptin (ball-and-stick) and active site residues (sticks) (PDB ID: 2rgu; Eckhardt et al., 2007). Figure 5. Hydrogen bonding interactions (green lines) between Diprotin A (ball-and-stick) and active site residues (sticks) (PDB ID: 1nu8; Thoma et al., 2003).

The co-crystal structure of DPP-4 and linagliptin (Eckhardt et al., 2007) reveals multiple interactions of the drug with its pharmacological target, DPP-4 (Figure 4). The aminopiperidine group of the drug occupies the and S2 sub-site of the enzyme and the amine of this group has hydrogen bonding interactions with Glu205 and Glu206 (Figures 3, 4). The hydrophobic butynyl group of the drug occupies the S1 site (Figure 3), and the uracil ring of the xanthine scaffold has π-stacking interactions with Tyr547 (Figure 4). Like the DPP-4 substrate, Diprotin-A, (Ile-Pro-Ile), linagliptin makes extensive hydrogen bonding interactions (represented as green lines) with the residues lining the enzyme active site. A comparison of the co-crystal structures of DPP-4 with linagliptin (PDB ID 2rgu, Figure 4) and Diprotin A with DPP-4 (PDB ID 1nu8, Figure 5) shows that linagliptin acts by occluding the DPP-4 active site and prevents binding of incretin hormones.

Pharmacologic Properties and Safety: 




Bioavailability (%)


(Nakamura et al., 2015)

IC50 (nM)

.1-2 nM


Ki (nM)

 1 nM

(Guedes et al., 2013)

Half-life (hrs)

120-184 hours

(Capuano et al., 2013)

Duration of Action

24 hours



Human intestinal absorption



multidrug resistance protein 1



Cytochrome p450 3A4



~85% urine; ~5% feces

(Capuano et al., 2013)

AMES Test (Carcinogenic Effect)

0.5444 (Non-AMES toxic)


hERG Safety Test (Cardiac Effect)

0.6109 (weak inhibitor)


Liver Toxicity

In 2014, a single case of liver injury due to linagliptin was reported.


Table 3. Pharmacokinetics: ADMET of linagliptin

The half-life elimination of linagliptin is 120-184 hours, a longer persistence in comparison to that of other DPP-4 inhibitors. For instance, saxagliptin has a half-life of roughly 2.2-3.8 hours and aloglitpin is cleared from the plasma within approximately 12.4-21.4 hours (Capuano et al., 2013). Linagliptin’s longer survival time is beneficial for individuals who may accidentally skip taking their medication since the drug may remain in the system for a few days. Therefore, a once-daily dosing is appropriate since inhibition of DPP-4 activity is sustained for a long period of time. Approximately 85-90% of the drug is excreted unchanged via the enterohepatic system as feces (80%) and urine (5%), while 10% of the drug is minimally metabolized by cytochrome P450 3A4 (CYP3A4).

Relative to the IC50 and Ki values of other DPP-4 inhibitor drugs, linagliptin is a competitive, selective and reversible inhibitor with Ki of 1 nM, indicating strong binding, and a low dissociation rate of the enzyme (Guedes et al., 2013). Both vildagliptin and linagliptin inhibit the DPP-4 enzyme by competition for the substrate binding site. However, unlike vildagliptin whose IC50 and Ki value are 62 nM and 10 nM, this drug dissociates from the DPP-4 enzyme at an approximately 10-fold slower rate, indicating that linagliptin is not as readily displaced by a substrate (Thomas et al., 2008). Because linagliptin is very selective of DPP-4 inhibition, there are fewer systemic side effects.

Drug Interactions and Side Effects: 




Total Number of Drugs Interactions



Major Drug Interactions

bexarotene and gatifloxacin


Alcohol/Food Interaction(s)

moderate interaction with alcohol (ethanol)


Disease Interaction(s)

pancreatitis (major)


On-target Side Effects

abdominal pain, upper respiratory tract infection, diarrhea, constipation, urinary tract infection (UTI), pancreatitis


Off-target Side Effects

nasopharyngitis, cough, angioedema, rash, headache, depression, anxiety; blurred vision, skin exfoliation


Table 4. Drug interactions and side effects of linagliptin

Hypoglycemia is uncommon with linagliptin alone (<1%), but occurs in higher rates when it is combined with other oral hypoglycemic agents. Concomitant administration of single doses of linagliptin with insulin secretagogues (e.g. glyburide) or insulin may cause an elevated risk of hypoglycemia and adverse cardiovascular complications (PubChem).

Regulatory Approvals/Commercial: 

Developed by Boehringer Ingelheim and approved by the US FDA in 2011, Tradjenta (linagliptin) is prescribed as an oral medication in 5 mg once a day, regardless of meals (DrugBank). The cost of a 30-day supply of 5mg tablets of linagliptin is about US $243.60 for a 30 day supply, which comes out to $8.12 /day. 



Food and Drugs Administration

National Institutes of Health (NIH)


Table 5. Links to Relevant Resources 


BindingDB: Linagliptin.

Capuano, A., Sportiello, L., Maiorino, M.I., Rossi, F., Giugliano, D., Esposito, K.. (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

Deacon, C.F, Holst, J.J. (2010). Linagliptin, a xanthine-based dipeptidyl peptidase-4 inhibitor with an unusual profile for the treatment of type 2 diabetes. Expert Opin Investig Drugs.  Jan;19(1):133-40. doi: 10.1517/13543780903463862.

DrugBank: Linagliptin. "Linagliptin: Indications, Side Effects, Warnings from Drugs.Com". N.p. Web. <>.

Eckhardt, M., Langkopf, E.Mark, M.Tadayyon, M.Thomas, L.Nar, H.Pfrengle, W.Guth, B.Lotz, R.Sieger, P.Fuchs, H.Himmelsbach, F. (2007). 8-(3-(R)-Aminopiperidin-1-Yl)-7-But-2-Ynyl-3-Methyl-1-(4-Methyl-Quinazolin-2-Ylmethyl)-3,7-Dihydropurine-2,6-Dione (BI 1356), a Highly Potent, Selective, Long-Acting, and Orally Bioavailable DPP-4 Inhibitor for the Treatment of Type 2 Diabetes. Journal of Medicinal Chemistry, 50: 6450-53. doi: 10.1021/jm701280z

Guedes, E.P., Hohl, A., de Melo, T.G., Lauand, F. (2013). Linagliptin: Farmacology, Efficacy and Safety in Type 2 Diabetes Treatment. Diabetololgy & Metabolic Syndrome, 5(25): 1-7. doi: 10.1186/1758-5996-5-25


Nakamura, Y., Hasegawa, H., Tsuji, M., Udaka, Y., Mihara, M., Shimizu, T., Inoue, M., Goto, Y., Gotoh, H., Inagaki, M., Oguchi, K. (2015). Diabetes Therapies in Hemodialysis Patients: Dipeptidase-4 Inhibitors. World Journal of Diabetes, 6(6): 840. doi: 10.4239/wjd.v6.i6.840.

Prabavathy, N. (2011). Linaglitpin – a Novel DPP-IV Inhibitor. International Journal of Pharma and Bio Sciences, 2(1): 438-42.

PubChem: Linagliptin.

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):947-59.  doi: 10.1016/S0969-2126(03)00160-6.

Thomas, L., Eckhardt, M., Langkopf, E., Tadayyon, M., Himmelsbach, F., 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(1): 175-82. doi: 10.1124/jpet.107.135723.

Summer 2016, Jennifer Jiang, Sutapa Ghosh; Reviewed by ***