A case of drug-induced hepatic injury associated with sitagliptin

Factors contributing to the adverse drug reactions associated with the dipeptidyl peptidase-4 (DPP-4) inhibitors: A scoping review

BACKGROUND AND AIM

Adverse drug reactions are one of the contributors to increased hospital admission and length of hospital stay. Among the various antidiabetic agents prescribed, dipeptidyl peptidase-4 (DPP-4) inhibitors have gained wide recognition and shown more persistence than other novel hypoglycemic agents. We performed a scoping review to identify the risk factors contributing to the adverse drug reactions with DPP-4 inhibitors.

METHODOLOGY

We followed Preferred Reporting Items for Scoping Review (PRISMA-ScR) Guidelines for reporting the findings. Data sources such as PubMed/MEDLINE, Scopus, Embase, and Cochrane were assessed. We included studies that reported the risk factors contributing to the DPP-4 inhibitor-associated adverse drug reactions. The Joanna Briggs Institute (JBI) critical appraisal checklist was used to assess the methodological quality of the studies.

RESULTS

Of the 6406 studies retrieved, 11 studies met our inclusion criteria. Of these 11 studies, seven were post-marketing surveillance studies, one nested case-control study, one comparator cohort study, one food and drug administration (FDA) adverse event reporting system (FAERS)-based observational study, and one questionnaire-based cross-sectional survey study. A total of eight factors were identified that contributed to the DPP-4 inhibitor-associated adverse drug reactions.

CONCLUSION

The included studies suggested age >65 years, females, grade 4 and 5 renal impairment, concomitant drugs, disease and drug therapy duration, liver disease, non-smokers, and non-hypertension as risk factors. Further studies should be conducted to provide insight into these risk factors so that the appropriate use of DPP-4 inhibitors in the diabetic population can be encouraged to improve the health-related quality of life.

PROSPERO REGISTRATION

CRD42022308764.

Incretin-Based Drugs and the Risk of Acute Liver Injury Among Patients With Type 2 Diabetes

OBJECTIVE

To determine whether the use of dipeptidyl peptidase 4 (DPP-4) inhibitors and glucagon-like peptide 1 receptor agonists (GLP-1 RAs), separately, is associated with an increased risk of acute liver injury compared with the use of sodium-glucose cotransporter 2 (SGLT-2) inhibitors.

RESEARCH DESIGN AND METHODS

We used the U.K. Clinical Practice Research Datalink linked with the Hospital Episode Statistics Admitted Patient Care and the Office for National Statistics databases to assemble two new-user, active-comparator cohorts. The first included 106,310 initiators of DPP-4 inhibitors and 27,277 initiators of SGLT-2 inhibitors, while the second included 9,470 initiators of GLP-1 RAs and 26,936 initiators of SGLT-2 inhibitors. Cox proportional hazards models with propensity score fine stratification weighting were used to estimate hazard ratios (HRs) and 95% CIs of acute liver injury.

RESULTS

Compared with SGLT-2 inhibitors, DPP-4 inhibitors were associated with a 53% increased risk of acute liver injury (HR 1.53, 95% CI 1.02-2.30). In contrast, GLP-1 RAs were not associated with an overall increased risk of acute liver injury (HR 1.11, 95% CI 0.57-2.16). However, an increased risk was observed among female users of both DPP-4 inhibitors (HR 3.22, 95% CI 1.67-6.21) and GLP-1 RAs (HR 3.23, 95% CI 1.44-7.25).

CONCLUSIONS

In this population-based study, DPP-4 inhibitors were associated with an increased risk of acute liver injury compared with SGLT-2 inhibitors in patients with type 2 diabetes. In contrast, an increased risk of acute liver injury was observed only among female GLP-1 RA users.

Prolonged effects of DPP-4 inhibitors on steato-hepatitic changes in Sprague-Dawley rats fed a high-cholesterol diet

OBJECTIVE

Sitagliptin and other dipeptidyl peptidase (DPP)-4 inhibitors/gliptins are antidiabetic drugs known to improve lipid profile, and confer anti-inflammatory and anti-fibrotic effects, which are independent of their hypoglycemic effects. However, in our previous short-term (35 days) studies, we showed that sitagliptin accentuates the hepato-inflammatory effects of high dietary cholesterol (Cho) in male Sprague-Dawley rats. Since most type 2 diabetics also present with lipid abnormalities and use DPP-4 inhibitors for glucose management, the present study was conducted to assess the impact of sitagliptin during long-term (98 days) feeding of a high Cho diet. An additional component of the present investigation was the inclusion of other gliptins to determine if hepatic steatosis, necro-inflammation, and fibrosis were specific to sitagliptin or are class effects.

METHODS

Adult male Sprague-Dawley rats were fed control or high Cho (2.0%) diets, and gavaged daily (from day 30 through 98) with vehicle or DPP-4 inhibitors (sitagliptin or alogliptin or saxagliptin). On day 99 after a 4 h fast, rats were euthanized. Blood and liver samples were collected to measure lipids and cytokines, and for histopathological evaluation, determination of hepatic lesions (steatosis, necrosis, inflammation, and fibrosis) using specific staining and immunohistochemical methods.

RESULTS

Compared to controls, the high Cho diet produced a robust increase in NASH like phenotype that included increased expression of hepatic (Tnfa, Il1b, and Mcp1) and circulatory (TNFα and IL-1β) markers of inflammation, steatosis, necrosis, fibrosis, and mononuclear cell infiltration. These mononuclear cells were identified as macrophages and T cells, and their recruitment in the liver was facilitated by marked increases in endothelium-expressed cell adhesion molecules. Importantly, treatment with DPP-4 inhibitors (3 tested) neither alleviated the pathologic responses induced by high Cho diet nor improved lipid profile.

CONCLUSIONS

The potential lipid lowering effects of DPP-4 inhibitors were diminished by high Cho (a significant risk factor for inducing liver damage). The robust inflammatory responses induced by high Cho feeding in long-term experiment were not exacerbated by DPP-4 inhibitors and a consistent hepatic inflammatory environment persisted, implying a prospective physiological adaptation.

Ascorbic Acid Ameliorates Cardiac and Hepatic Toxicity Induced by Azithromycin-Etoricoxib Drug Interaction

The complexity of prescribing safe and effective drug therapy is still challenging. Due to the increased number of medications taken by patients, the potential for drug-drug interactions has clinically important consequences. This study focuses on the potential drug-drug interaction between azithromycin and etoricoxib and the possibility of counteracting this adverse reaction by giving ascorbic acid intraperitoneally to male albino rats. Sixty adult male albino rats weighing 150–180 g were used. The rats were allocated into six equal groups. One group was a control, and the others were given azithromycin, etoricoxib, either alone or combination, with one group treated with ascorbic acid and the last group treated with the drug combination and ascorbic acid. Blood samples were collected for measuring AST, ALT, LDH, CK-MB, and troponin alongside antioxidant enzymes and histopathological examination for both liver and heart tissue. The results showed both hepatic and cardiac damage in azithromycin and etoricoxib groups represented by increasing levels of heaptoc enzymes (ALT, AST, LDH, CK-MB, and troponin) with declining antioxidant enzymes and elevation of malondialdehyde and the appearance of hepatic and cardiac toxicities. Upon administration, ascorbic acid ameliorated all the mentioned biochemical parameters. In conclusion, ascorbic acid has great antioxidant capacities and hepatic and cardiac ameliorative effects and can alleviate drug interaction toxicity.

Antidiabetic Drug Sitagliptin with Divalent Transition Metals Manganese and Cobalt: Synthesis, Structure, Characterization Antibacterial and Antioxidative Effects in Liver Tissues

Metals and their complexes have an increasing number of medical applications. Sitagliptin (STG) acts as an antidiabetic drug. Mn(II) and Co(II) complexes were studied and characterized based on physical characterization, FT-IR, DG/TG, XRD, ESM, and TEM. Data revealed that STG acts as a bidentate ligand through the oxygen atom of a carbonyl group and the nitrogen atom of an amino group. Magnetic measurement data revealed that the Mn/STG metal complex has a square planner geometry. The experiment was performed on 40 male albino rats who were divided into four groups: the control group, STG group, group treated with STG/Mn, and group treated with Co/STG. Biomarkers for hepatic enzymes and antioxidants were found in the blood, and hepatic tissue histology was evaluated. STG in combination with Mn and Co administration showed potent protective effects against hepatic biochemical alterations induced by STG alone, as well as suppressing oxidative stress and structural alterations. These complexes prevented any stress and improved hepatic enzymatic levels more than STG alone. The STG/Mn complex was highly effective against Bacillus subtilis and Streptococcus pneumonia, while STG/Co was highly effective against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureas. Therefore, STG combined with Mn and Co produced a synergistic effect against oxidative stress and improved the histological structure of the liver tissues. STG metal complexes with Mn and Co showed the most potential ameliorative antioxidant and hepatoprotective effects.

High levels of dietary methionine improves sitagliptin-induced hepatotoxicity by attenuating oxidative stress in hypercholesterolemic rats

Background

Both cholesterol (Cho) and methionine (Met, a precursor for homocysteine) are risk factors for fatty liver disease. Since Western diets are rich in Cho and Met, we investigated the hepatic effects of feeding a diet enriched in Met and Cho. Further, based on the reported anti-oxidative and lipid lowering properties of sitagliptin (an antidiabetic drug), we tested whether it could counteract the negative effects of high Cho and Met. We therefore hypothesized that sitagliptin would ameliorate the development of liver pathology that is produced by feeding diets rich in either Cho, Met, or both.

Methods

Male Sprague Dawley rats were fed ad libitum a) control diet, or b) high Met or c) high Cho, or d) high Met + high Cho diets for 35 days. From day 10 to 35, 50% of rats in each dietary group were gavaged with either vehicle or an aqueous suspension of sitagliptin (100 mg/kg/day). Liver samples were harvested for histological, molecular, and biochemical analyses.

Results

The high Cho diet produced significant hepatic steatosis which was unaffected by sitagliptin. Contrary to expectation, sitagliptin exacerbated expression of hepatic markers of oxidative stress and fibrosis in rats fed high Cho. Corresponding increases in 4-hydroxynonenal adducts and collagen deposition were demonstrated by immunohistochemistry and sirius red staining. These hepatic changes were absent in rats on the high Met diet and they were comparable to controls. The inclusion of Met in the high Cho diet resulted in significant reduction of the hepatic steatosis, oxidative stress, and fibrosis produced by high Cho alone.

Conclusion

Sitagliptin exacerbated the effects of high Cho on both oxidative stress and fibrosis, resulting in NASH like symptoms that were significantly reversed by the inclusion of Met.

Sitagliptin-Dependent Differences in the Intensity of Oxidative Stress in Rat Livers Subjected to Ischemia and Reperfusion

Purpose

Ischemia/reperfusion (IR) is the main cause of liver damage after transplantation. We evaluated the effect of sitagliptin (STG) on oxidative stress parameters in the rat liver under IR.

Methods

Rats were treated with STG (5 mg/kg) (S and SIR) or saline solution (C and CIR). Livers from CIR and SIR were subjected to ischemia (60 min) and reperfusion (24 h). During reperfusion, aminotransferases (ALT and AST) were determined in blood samples. Thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), catalase (CAT), paraoxonase-1 (PON1), glutathione peroxidase (GPx), and the mRNA expression of SOD1 were determined in liver homogenates after reperfusion. Different regions of livers were also histologically evaluated.

Results

The PON1 activity was higher, and the TBARS level was lower in SIR than in CIR. There was an inverse relationship between TBARS and PON1 levels in the whole cohort. The GPx activity was lower in ischemic than in nonischemic groups regardless of the STG treatment. In SIR, the SOD1 activity was higher compared to that in CIR. In S, the expression of SOD1 mRNA was the highest of all examined groups and positively correlated with the SOD1 activity in the whole animal cohort. During IR aminotransferases, the activity in the drug-treated group was lower in all examined points of time. In drug-treated groups, the percentage of steatosis was higher than that in nontreated groups regardless of IR.

Conclusions

The protective effect of STG on the rat liver, especially its antioxidant properties, was revealed under IR conditions.

The incretin enhancer, sitagliptin, exacerbates expression of hepatic inflammatory markers in rats fed a high-cholesterol diet

OBJECTIVE

Hypercholesterolemia is associated with the development of a pro-inflammatory state and is a documented risk factor for progression to insulin resistance, nonalcoholic fatty liver and cardiovascular diseases. Sitagliptin is an incretin enhancer that improves glucose tolerance by inhibiting dipeptidyl peptidase-4, but it also has reported anti-inflammatory effects. The current study was thus undertaken to examine the interactions of dietary Cholesterol (Cho) and sitagliptin on markers of inflammation.

METHODS

Male Sprague-Dawley rats were provided diets high in Cho and gavaged with vehicle or an aqueous suspension of sitagliptin (100 mg/kg/day) from day 10 through day 35. Molecular methods were used to analyze the lipid profile and inflammatory markers in liver and serum samples. H&E-stained liver sections were used for histopathological evaluation. Hepatic influx of mononuclear cells and necrosis were assessed by immunohistochemistry.

RESULTS

Sitagliptin reduced triglyceride and Cho levels in serum of rats on the control diet but these effects were abrogated in rats on the high-Cho diet. Sitagliptin produced a significant increase in the expression of hepatic inflammatory markers (Tnfa, Il1b, and Mcp1) and a corresponding increase in serum TNFα and IL-1β in rats on the high-Cho diet, but it had no effect on rats on the control diet. Additionally, sitagliptin had no effect on liver morphology in rats on the control diet, but it produced hepatic histopathological changes indicative of necrosis and mononuclear cell infiltration in rats on the high-Cho diet. These mononuclear cells were identified as macrophages and T cells.

CONCLUSION

When provided in the context of a high-Cho diet, these findings reveal previously unrecognized hepato-inflammatory effects of sitagliptin that are accompanied by evidence of hepatic necrosis and mononuclear cell infiltration.

Kombiglyze (metformin and saxagliptin)-induced hepatotoxicity in a patient with non-alcoholic fatty liver disease

A 33‐year‐old man was referred with hyperosmotic symptoms of 4 weeks. Clinical examination showed palpable hepatomegaly and no stigmata of liver disease. Findings were random glucose 16.6 mmol/L, HbA1c 12.4%, triglyceride 6.2 mmol/L, normal LFTs and ultrasound liver: increased echogenicity. Management consisted of dietician referral and commencement of metformin 500 mg bd, diamicron MR 60 mg od, and fenofibrate 145 mg od. He was non‐compliant, complaining of “heaviness of head” after consuming oral diabetic agents, without symptoms of hypoglycemia. Treatment was switched to Kombiglyze XR (saxaglipitin 5 mg + metformin 1000 mg) and empagliflozin 25 mg od. He presented 1 week later with generalised pruritus with ALT 307 IU/L and serum GGT 808 IU/L. Following this, a percutaneous liver biopsy was performed, revealing steatohepatitis and marked intra‐hepatic cholestasis. Kombiglyze XR was withheld, with resolution of LFTs to baseline. Phenotypes of liver injury are categorised according to R value, defined as ratio ALT/ULN:ALP/ULN. R value of ≥5:hepatocellular injury, ≤2:cholestatic injury, 2–5:mixed‐type injury. Here, R value points toward mixed type (R = 3.203). Hepatotoxicity in patients with NASH is difficult to diagnose, based on laboratory parameters. Liver histology was useful in indicating additional changes apart from NASH, causing liver derangement. The Rousal Uclaf Causality Assessment Method is a scoring method to determine the probability of drug induced liver injury. RUCAM score for this case was 6 (probable adverse drug reaction). Hepatotoxicity from saxagliptin not been reported prior. Clinicians need to be more vigilant, particularly in patients with NASH.

Identification of a novel metabolite of vildagliptin in humans: Cysteine targets the nitrile moiety to form a thiazoline ring

The dipeptidyl peptidase-4 (DPP-4) inhibitor vildagliptin (VG) is used to treat type 2 diabetes. In rare cases, VG-induced liver injury has been reported. One case report suggested that immune responses were involved in the hepatotoxicity. However, the underlying mechanisms of VG-induced hepatotoxicity are uncertain. In the present study, we investigated whether VG has the potential to covalently bind to macromolecules in cells, a process that could initiate immune-mediated hepatotoxicity. For comparison, M20.7, a major metabolite of VG, and other DPP-4 inhibitors were also evaluated. We found that VG and anagliptin (ANG), which both contain a cyanopyrrolidine moiety, rapidly reacted in non-enzymatic manners on co-incubation with l-cysteine. Both VG and ANG had half-lives of 20-30 min. In contrast, incubation with GSH, rather than l-cysteine, failed to decrease the concentrations of VG or ANG. M20.7, sitagliptin, linagliptin, and alogliptin, having no cyanopyrrolidine moiety, were stable on incubation with l-cysteine or GSH. Structural analysis of the VG- and ANG-cysteine adducts, designated M407 and M487, respectively, revealed that the nitrile moieties of VG and ANG were irreversibly converted to a thiazoline acid. In conclusion, we found that VG and ANG have the potential to covalently bind to a thiol residue of l-cysteine in proteins. Such binding may lead to unpredictable immune responses in humans. l-Cysteine, rather than GSH, would likely be useful to detect the potential for covalent binding that could initiate immune-mediated hepatotoxicity.

Acute Liver Injury Induced by Sitagliptin: Report of Two Cases and Review of Literature

We present two cases of acute liver injury associated with sitagliptin. The first case was a 58-year-old male with a history of poorly controlled type 2 diabetes mellitus and hyperlipidemia. Sitagliptin was added for better control of diabetes. After initiation of sitagliptin, the patient's serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels increased gradually over a period of six months. The second case was a 44-year-old female with type 2 diabetes mellitus, and she experienced a more than ten-fold elevation in ALT and AST levels after starting sitagliptin therapy. Both patients did not have any history of alcohol abuse, acetaminophen use, or chronic liver disease. In the literature review, the reported magnitude of liver enzyme derangement with sitagliptin is generally mild and transient (two-fold upper limit of normal). We believed that the acute derangement of ALT and AST in our patients was due to sitagliptin since the ALT and AST normalized shortly after sitagliptin was discontinued and remained at baseline after resuming all other medications. Further research is needed to understand the mechanism of dipeptidyl peptidase 4 (DPP-4) inhibitors associated liver injury.

Drug Hepatotoxicity: Newer Agents

Idiosyncratic hepatotoxicity is one of the most common reasons for an approved drug being restricted. This article focuses on hepatotoxicity of selected and recently introduced agents, such as, tyrosine kinase inhibitors, monoclonal antibodies, novel oral anticoagulants, newer antiplatelets, antibiotics, anti-diabetics, anti-epileptics, anti-depressants, anti-psychotics and anti-retrovirals. Overall, the incidence of clinically relevant hepatotoxicity from newer agents seems to be lower than that of the older agents. Nevertheless, cases of severe hepatotoxicity have been reported due to some of these newer agents, including, trastuzumab, ipilimumab, infliximab, imatinib, bosutinib, dasatinib, gefitinib, erlotinib, sunitinib, ponatinib, lapatinib, vemurafenib, dabigatran, rivaroxaban, felbamate, lamotrigine, levetiracetam, venlafaxine, duloxetine, darunavir, and maraviroc.

Pharmacokinetics in patients with chronic liver disease and hepatic safety of incretin-based therapies for the management of type 2 diabetes mellitus

Patients with type 2 diabetes mellitus have an increased risk of chronic liver disease (CLD) such as non-alcoholic fatty liver disease and steatohepatitis, and about one-third of cirrhotic patients have diabetes. However, the use of several antidiabetic agents, such as metformin and sulphonylureas, may be a concern in case of hepatic impairment (HI). New glucose-lowering agents targeting the incretin system are increasingly used for the management of type 2 diabetes. Incretin-based therapies comprise oral inhibitors of dipeptidyl peptidase-4 (DPP-4) (gliptins) or injectable glucagon-like peptide-1 (GLP-1) receptor agonists. This narrative review summarises the available data regarding the use of both incretin-based therapies in patients with HI. In contrast to old glucose-lowering agents, they were evaluated in specifically designed acute pharmacokinetic studies in patients with various degrees of HI and their hepatic safety was carefully analysed in large clinical trials. Only mild changes in pharmacokinetic characteristics of DPP-4 inhibitors were observed in patients with different degrees of HI, presumably without major clinical relevance. GLP-1 receptor agonists have a renal excretion rather than liver metabolism. Specific pharmacokinetic data in patients with HI are only available for liraglutide. No significant changes in liver enzymes were reported with DPP-4 inhibitors or GLP-1 receptor agonists, alone or in combination with various other glucose-lowering agents, in clinical trials up to 2 years in length. On the contrary, preliminary data suggested that incretin-based therapies may be beneficial in patients with CLD, more particularly in the presence of non-alcoholic fatty liver disease. Nevertheless, caution should be recommended, especially in patients with advanced cirrhosis, because of a lack of clinical experience with incretin-based therapies in these vulnerable patients.

Liraglutide-induced autoimmune hepatitis

IMPORTANCE

Use of incretin-based hypoglycemic agents is increasing, but safety data remain limited. We treated a woman with marker-negative autoimmune hepatitis associated with the glucagon-like peptide 1 agonist liraglutide.

OBSERVATIONS

A young woman with type 2 diabetes mellitus and vitiligo presented with a 10-day history of acute hepatitis. Other than starting liraglutide therapy 4 months prior, she reported no changes in medication therapy and no use of supplements. At admission, aspartate aminotransferase level was 991 U/L; alanine aminotransferase level, 1123 U/L; total bilirubin level, 9.5 mg/dL; and international normalized ratio, 1.3. Results of a liver biopsy demonstrated interface hepatitis with prominent eosinophils and rare plasma cells. The patient's liraglutide therapy was withheld at discharge but her symptoms worsened. A second biopsy specimen revealed massive hepatic necrosis. She started oral prednisone therapy for presumed liraglutide-induced marker-negative autoimmune hepatitis.

CONCLUSIONS AND RELEVANCE

This case represents, to our knowledge, the first report of liraglutide-induced autoimmune hepatitis. Hepatotoxicity may be an incretin analogue class effect with a long latency period. This case raises prescriber awareness about the potential adverse effects of glucagon-like peptide 1 agonists. Postmarketing studies are needed to define the hepatotoxic potential of these agents.

The pharmacokinetic considerations and adverse effects of DPP-4 inhibitors [corrected]

INTRODUCTION

Dipeptidyl-peptidase-4 (DPP-4) inhibitors are a class of anti-hyperglycemic agents with proven efficacy in patients with type 2 diabetes mellitus (T2DM).

AREAS COVERED

This review considers the pharmacokinetic profile, adverse effects and drug interactions of DPP-4 inhibitors. DPP-4 inhibitors have certain differences in their structure, metabolism, route of elimination and selectivity for DPP-4 over structurally related enzymes, such as DPP-8/DPP-9. They have a low potential for drug interactions, with the exception of saxagliptin that is largely metabolized by cytochrome CYP3A4/A5. Reports of pancreatitis and pancreatic cancer have raised concerns regarding the safety of DPP-4 inhibitors and are under investigation. Post-marketing surveillance has revealed less common adverse effects, especially a number of skin- and immune-related adverse effects. These issues are covered in the present review.

EXPERT OPINION

DPP-4 inhibitors are useful and efficient drugs. DPP-4 inhibitors have similar mechanism of action and similar efficacy. However, DPP-4 inhibitors have certain differences in their pharmacokinetic properties that may be associated with different clinical effects and adverse event profiles. Although clinical trials indicated a favorable safety profile, post-marketing reports revealed certain safety aspects that need further investigation. Certainly, more research is needed to clarify if the differences among DPP-4 inhibitors could lead to a different clinical and safety profile.

Pharmacokinetic and toxicological considerations for the treatment of diabetes in patients with liver disease

INTRODUCTION

Patients with type 2 diabetes have an increased risk of chronic liver disease (CLD) such as non-alcoholic fatty liver disease and steatohepatitis and about one-third of cirrhotic patients have diabetes. However, the use of several antidiabetic agents may be a cause for concern in the case of hepatic impairment (HI).

AREAS COVERED

An extensive literature search was performed to analyze the influence of HI on the pharmacokinetics (PK) of glucose-lowering agents and the potential consequences for clinical practice as far as the efficacy/safety balance of their use in diabetic patients with CLD is concerned.

EXPERT OPINION

Almost no PK studies have been published regarding metformin, sulfonylureas, thiazolidinediones and α-glucosidase inhibitors in patients with HI. Only mild changes in PK of glinides, dipeptidyl peptidase-4 inhibitors and sodium glucose cotransporters type 2 inhibitors were observed in dedicated PK studies in patients with various degrees of HI, presumably without major clinical relevance although large clinical experience is lacking. Glucagon-like peptide-1 receptor agonists have a renal excretion rather than liver metabolism. Rare anecdotal case reports of hepatotoxicity have been described with various glucose-lowering agents contrasting with numerous reassuring data. Nevertheless, caution should be recommended, especially in patients with advanced cirrhosis, including with the use of metformin.

Dipeptidyl peptidase-4 inhibitors: multitarget drugs, not only antidiabetes drugs

Dipeptidyl peptidase (DPP)-4 inhibitors are a new class of antidiabetic agents that reduce blood glucose by preventing the degradation of the endogenous incretin hormones glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide. Protection by DPP-4 inhibitors of β-cell function has been demonstrated in patients with type 2 diabetes. Because DPP-4 is an enzyme widely expressed in humans, DPP-4 inhibitors are speculated to be multitarget agents. However, other potential therapeutic benefits of DPP-4 inhibitors remain unknown. Recently, some therapeutic effects of DPP-4 inhibitors, such as immune regulation, cardiovascular protection, and anti-inflammatory effects, have been observed. This article provides a systematic and comprehensive review of current research into the newly found effects and mechanism of action of DPP-4 inhibitors in a therapeutic context.

Probable linagliptin-induced liver toxicity: a case report

AIM

Unlike other dipeptidyl peptidase 4 (DPP-4) inhibitors, the excretion of linagliptin is mainly through a biliary route. Despite this fact, liver injury with linagliptin has thus far not been reported in the literature. However, this report describes the first case of probable linagliptin-induced liver toxicity.

METHODS

The clinical history, diagnosis, investigations and drug treatment of the patient are reviewed here.

RESULTS

A 58-year-old Japanese woman presented with fatigue, nausea, jaundice and marked elevations of hepatic enzymes 4weeks after starting linagliptin 5mg/day as monotherapy. No other medications were taken, and imaging studies revealed no other obvious causes of hepatic injury. Tests for viral serology and antinuclear antigen were negative. Symptoms disappeared and the levels of hepatic parameters (serum aminotransferases and biliary enzymes) slowly recovered after discontinuation of linagliptin. The slow recovery process may have been due to the very long half-life of the drug. The patient's Naranjo scale score was 6 and RUCAM score was 7.

CONCLUSION

Although linagliptin currently carries no liver warnings, it may be necessary to monitor hepatic function in some patients upon administration of this drug until further evidence is obtained.

Dipeptidyl peptidase IV inhibitor improves the salivary gland histology of spontaneously diabetic mice

OBJECTIVES

The incretin-based therapy might be effective in patients possessing certain levels of preserved pancreatic beta-cells. However, doubts still exist regarding the efficacy of this atment in the recovery of tissues damaged by type 1 diabetes. Thus, the objective of this study was to evaluate the treatment with MK0431 in salivary glands of spontaneously diabetic mice, focusing mainly on the possible therapeutic and hypoglycaemic effects of this dipeptidyl peptidase IV inhibitor in the recovery of these salivary tissues.

METHODS AND RESULTS

Twenty mice were divided into two groups of 10 animals each: group I (NOD diabetic/untreated) and group II (NOD diabetic MK0431/treated). The group II was treated during 4 weeks with MK0431 mixed in the food. The group I was maintained in the same way without receiving, however, any treatment. Glucose levels were monitored during treatment and salivary glands samples were collected at the end of treatment for the histological examination under both transmitted and polarized light microscopy. High glucose levels were observed in untreated animals, while in animals with treatment, reduction of these levels was observed. Tissue restructuring was also observed in animals submitted to therapy with MK0431, mainly in relation to the attempt to extracellular matrix reorganization.

CONCLUSIONS

According to results, the treatment with this dipeptidyl peptidase IV inhibitor contributed to the general homeostasis of the organism and to the reestablishment of both epithelial and stromal compartments which were damaged by the hyperglycaemic condition, demonstrating that the incretin-based therapy may be an important complementary treatment for the type 1 diabetic condition.