Review
Diclofenac-induced liver injury: a paradigm of idiosyncratic drug toxicity

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Abstract

The nonsteroidal antiinflammatory drug diclofenac causes rare but significant cases of serious hepatotoxicity, typically with a delayed onset (>1–3 months). Because there is no simple dose relationship and because liver injury cannot be reproduced in current animal models, individual patient-specific susceptibility factors have been evoked to account for the increased risk. While these patient factors have remained undefined, a number of molecular hazards have been characterized. Among these are metabolic factors (bioactivation by hCYP2C9 or hCYP3A4 to thiol-reactive quinone imines, activation by hUGT2B7 to protein-reactive acyl glucuronides and iso-glucuronides, and 4′-hydroxylation secondary to diclofenac glucuronidation), as well as kinetic factors (Mrp2-mediated concentrative transport of diclofenac metabolites into bile). From the toxicodynamic view, both oxidative stress (caused by putative diclofenac cation radicals or nitroxide and quinone imine-related redox cycling) and mitochondrial injury (protonophoretic activity and opening of the permeability transition pore) alone or in combination have been implicated in diclofenac toxicity. In some cases, immune-mediated liver injury is involved, inferred from inadvertent rechallenge data and from a number of experiments demonstrating T cell sensitization. Why certain underlying diseases (e.g., osteoarthritis) also increase the susceptibility to diclofenac hepatotoxicity is not clear. To date, cumulative damage to mitochondrial targets seems a plausible putative mechanism to explain the delayed onset of liver failure, perhaps even superimposed on an underlying silent mitochondrial abnormality. Increased efforts to identify both patient-specific risk factors and disease-related factors will help to define patient subsets at risk as well as increase the predictability of unexpected hepatotoxicity in drug development.

Introduction

Diclofenac (Voltaren and a number of generics) is a nonsteroidal antiinflammatory drug (NSAID) widely used for treatment of a variety of rheumatoid disorders, including osteoarthritis, rheumatoid arthritis, ankylosing spondylitis, and acute muscle pain. Similar to other NSAIDs, diclofenac causes, in rare instances, hepatic injury in patients. Although the apparent incidence rate of severe diclofenac-induced hepatic adverse drug reactions (ADRs) is very low (estimates range from 1 to 2 cases per million prescriptions (Purcell et al., 1991) to 6 to 18 cases/100,000 person-years (Walker, 1997), it is the large number of patients treated worldwide with diclofenac that makes the absolute number of hepatic cases appear impressive. In fact, published cases of severe diclofenac hepatotoxicity amount to approximately 250 reports, with a case fatality rate of approximately 10% (Lewis, 2003), but the number of total serious hepatic adverse reactions (mostly unpublished) reported to the health authorities is severalfold higher. Worse even, the real incidence has been estimated to be 10- to 20-fold higher than all reported cases, due to notorious underreporting (Sgro et al., 2002). These numbers, however, have to be seen as always against the background of millions of people successfully treated with this NSAID.

The pathogenesis of low-incidence/high-severity diclofenac hepatotoxicity is largely unknown. One reason for this is the apparent lack of animal models available to date that mimic the human situation and with which one could investigate the mechanisms of the toxic response. Clearly, because liver injury from diclofenac is not a reproducible effect and lacks a simple dose–response relationship, it is generally accepted that individual patient-specific susceptibility factors eventually determine whether a patient will tolerate the drug (as in the vast majority of cases) or whether an individual in rare cases will develop a toxic response. Thus, diclofenac-induced liver injury is a typical example of idiosyncratic drug toxicity (see below). This notion alone, however, will not tell us anything about the mechanism.

There are two major and plausible reasons why it is not only desirable but indispensable to better understand the mechanisms of diclofenac injury at the molecular level. Insight in these underlying mechanisms will improve prediction, in particular

  • (1)

    to help identify populations (subsets) at increased risk, as well as identify biomarkers that would point to an increased risk for an individual; and

  • (2)

    to assist in candidate selection during the development of new drugs (let us recall that a significant number of other, related NSAIDs had to be removed from the market because of an unacceptably high risk of hepatic toxicity and that the development of certain new promising drugs had to be discontinued, sometimes at a late stage of progression, due to unpredictable liver liability).

A number of reviews on NSAID-induced liver injury are available Tolman, 1990, Rabinovitz and VanThiel, 1992, Carson et al., 1993, Farrell, 1994, Garcia Rodriguez et al., 1994, Boelsterli et al., 1995, Fry and Seeff, 1995, Manoukian and Carson, 1996, Boelsterli, 2002a, Boelsterli, 2002c, Lewis, 2003. Many NSAIDs share among themselves certain critical pathways of bioactivation, disposition, and toxic responses in the liver. The aim of this review, however, is to be topical rather than comprehensive, and to summarize the diclofenac-specific recent advances in the field. The past years have seen major progress in the understanding of certain diclofenac-specific mechanisms of liver cell injury at the molecular level, and a number of crucial pathways have been identified, while others still remain in the dark. These new insights into some of the underlying mechanisms can hopefully be translated into predictive tools for risk evaluation both at the patient level and at the drug development level.

Section snippets

Idiosyncratic drug hepatotoxicity

More than 50% of all cases of acute liver failure can be attributed to drugs (Gill and Sterling, 2001). Among these, acetaminophen is the most common cause. While acetaminophen produces predictable and dose-dependent acute toxicity (Cohen et al., 1998), 14% of all cases of acute liver failure encompass unexpected and unpredictable drug reactions from a large variety of other drugs. Thus, it is now generally accepted that drugs are the single major cause of acute liver failure (in the Western

Pathology and clinical phenotype of diclofenac hepatotoxicity: a clue to understanding mechanisms?

Histopathological analysis of liver specimens (upon biopsy or autopsy) of patients with diclofenac-induced liver injury alone cannot reveal probable modes of diclofenac hepatotoxicity. This is because in the majority of cases such liver samples are not available and because in those very few available they represent a terminal stage of injury that is commonly found as a result of drug-induced liver failure. Specifically, the typical pathologic picture is hepatic necrosis (usually diffuse but

Putative mechanisms of diclofenac hepatotoxicity

In idiosyncratic drug toxicity, mechanisms pertaining to the drug (molecule), the individual (patient), and the underlying disease (therapeutic indication) all contribute to the overall pathogenesis. Here, new pieces of experimental evidence that have given us more insights into some of the putative mechanisms (viewed from both the toxicokinetic and toxicodynamic perspective) are discussed, with a focus on the most recent advances.

The molecule

Diclofenac (sodium salt, Mr = 318.1) is a lipophilic and weakly acidic compound (Poct = 28.4; pKa = 3.9) (Sengupta et al., 1985) that features two twisted aromatic rings (Sallmann, 1985). Important for its behavior in hepatocytes are two structural components (Fig. 1). First, it is a phenylacetic acid derivative, with the carboxylic acid moiety being the substrate for the production of reactive glucuronide metabolites (see below). Second, diclofenac has a diphenylamine backbone, with the

The patient

On the search of genetic or acquired patient factors, polymorphisms and other, more rarely (<1%) occurring, abnormalities in the expression of drug-metabolizing enzymes or other key proteins have increasingly been scrutinized. However, the link between such individual variations and the occurrence of diclofenac-induced liver injury has proven extremely difficult so far. For example, because the formation of an electrophilic intermediate (the 2,5-quinone imine, as inferred from the urinary

The underlying disease

Factors of the preexisting disease (pathophysiological alterations, altered gene expression, and altered toxic response) can greatly modulate the susceptibility to drug-induced hepatotoxicity (Boelsterli, 2003b). For example, the condition of rheumatoid arthritis (as opposed to other therapeutic indications that are treated with NSAIDs) can increase the risk for NSAID-induced liver injury by 10-fold (Rodriquez et al., 1994). Specifically for diclofenac, osteoarthritis is a risk factor. This can

New mechanistic insights from transcriptomics and proteomics

The advent of the novel toxicogenomics techniques made possible for the first time comparative expression profiles for thousands of genes. While the validation of these techniques (for prediction) is still ongoing, it has become clear (perhaps not too surprisingly) that for many drugs that are potentially hepatotoxic the gene expression profiles correlate well with traditional histopathological and biochemical analyses (Waring et al., 2001). No data are available for diclofenac or related

Conclusions

Based on the numerous reports on diclofenac-induced liver injury (both clinical reports and experimental studies), diclofenac has developed into a paradigm of NSAID-induced idiosyncratic hepatotoxicity (although the estimated incidence rate is not higher than that for some other NSAIDs). Thus, on the one hand, our insights into many of the underlying molecular pathways has considerably increased. A number of diclofenac-related hazards have been identified and studied in detail. These include

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Conflict of interest statement

There are no conflicts of interest.

References (106)

  • S.W. Fry et al.

    Hepatotoxicity of analgesics and anti-inflammatory agents. Gastroenterol

    Clin. North Am.

    (1995)
  • G. Galati et al.

    Idiosyncratic NSAID drug induced oxidative stress

    Chem.–Biol. Interact.

    (2002)
  • M.L. Gil et al.

    Immunochemical detection of protein adducts in cultured human hepatocytes exposed to diclofenac

    BBA–Mol. Basis Dis.

    (1995)
  • P. Griem et al.

    Allergic and autoimmune reactions to xenobioticshow do they arise?

    Immunol. Today

    (1998)
  • B.W. Gutting et al.

    Oxazolone and diclofenac-induced popliteal lymph node assay reactions are attenuated in mice orally pretreated with the respective compoundpotential role for the induction of regulatory mechanisms following enteric administration

    Toxicol. Appl. Pharmacol.

    (2003)
  • B.W. Gutting et al.

    Diclofenac activates T cells in the direct popliteal lymph node assay and selectively induces IgG1 and IgE against co-injected TNP-OVA

    Toxicol. Lett.

    (2002)
  • E.J. Hickey et al.

    Diclofenac induced in vivo nephrotoxicity may involve oxidative stress-mediated massive genomic DNA fragmentation and apoptotic cell death

    Free Radical Biol. Med.

    (2001)
  • M. Jurima-Romet et al.

    Comparative cytotoxicity of non-steroidal anti-inflammatory drugs in primary cultures of rat hepatocytes

    Toxicol. In Vitro

    (1994)
  • A.J. Kowaltowski et al.

    Opening of the mitochondrial permeability transition pore by uncoupling or inorganic phosphate in the presence of Ca2+ is independent of mitochondrial-generated reactive oxygen species

    FEBS Lett.

    (1996)
  • A. Kretz-Rommel et al.

    Diclofenac covalent protein binding is dependent on acyl glucuronide formation and is inversely related to acute cell injury in cultured rat hepatocytes

    Toxicol. Appl. Pharmacol.

    (1993)
  • A. Kretz-Rommel et al.

    Cytotoxic activity of T cells and non-T cells from diclofenac-immunized mice against cultured syngeneic hepatocytes exposed to diclofenac

    Hepatology

    (1995)
  • A.P. Li

    A review of the common properties of drugs with idiosyncratic hepatotoxicity and “multiple determinant hypothesis” for the manifestation of idiosyncratic drug toxicity

    Chem.–Biol. Interact.

    (2002)
  • Y. Masubuchi et al.

    Role of mitochondrial permeability transition in diclofenac-induced hepatocyte injury in rats

    Hepatology

    (2002)
  • R. Moreno-Sanchez et al.

    Inhibition and uncoupling of oxidative phosphorylation by nonsteroidal anti-inflammatory drugs

    Biochem. Pharmacol.

    (1999)
  • D. Pessayre et al.

    Withdrawal of life support, altruistic suicide, fratricidal killing and euthanasia by lymphocytesdifferent forms of drug-induced hepatic apoptosis

    J. Hepatol.

    (1999)
  • I. Petrescu et al.

    Uncoupling effects of diclofenac and aspirin in the perfused liver and isolated hepatic mitochondria of rat

    Biochim. Biophys. Acta (Bioenergetics)

    (1997)
  • M. Pirmohamed et al.

    The danger hypothesispotential role in idiosyncratic drug reactions

    Toxicology

    (2002)
  • X. Ponsoda et al.

    Molecular mechanism of diclofenac hepatotoxicityassociation of cell injury with oxidative metabolism and decrease in ATP levels

    Toxicol In Vitro

    (1995)
  • R.A. Roth et al.

    Is exposure to bacterial endotoxin a determinant of susceptibility to intoxication from xenobiotic agents?

    Toxicol. Appl. Pharmacol.

    (1997)
  • A. Sakai

    Diclofenac inhibits endothelial cell adhesion molecule expression induced with lipopolysaccharide

    Life Sci.

    (1996)
  • M.H. Schoemaker et al.

    Resistance of rat hepatocytes against bile acid-induced apoptosis in cholestatic liver injury is due to nuclear factor-kappa B activation

    J. Hepatol.

    (2003)
  • S. Seitz et al.

    Diclofenac acyl glucuronide, a major biliary metabolite, is directly involved in small intestinal injury in rats

    Gastroenterology

    (1998)
  • C. Sgro et al.

    Incidence of drug-induced hepatic injuriesa French population-based study

    Hepatology

    (2002)
  • A.G. Siraki et al.

    Endogenous and endobiotic induced reactive oxygen species formation by isolated hepatocytes

    Free Radical. Biol. Med.

    (2002)
  • S.A. Uyemura et al.

    Diclofenac sodium and mefenamic acidpotent inducers of the membrane permeability transition in renal cortex mitochondria

    Arch. Biochem. Biophys.

    (1997)
  • G.P. Aithal et al.

    Relationship of polymorphism in CYP2C9 to genetic susceptibility to diclofenac-induced hepatitis

    Pharmacogenetics

    (2000)
  • U.A. Boelsterli

    Mechanisms underlying the hepatotoxicity of nonsteroidal anti-inflammatory drugs

  • U.A. Boelsterli

    Xenobiotic acyl glucuronides and acyl CoA thioesters as protein-reactive metabolites with the potential to cause idiosyncratic drug reactions

    Curr. Drug Metab.

    (2002)
  • U.A. Boelsterli

    Mechanisms of NSAID-induced hepatotoxicityfocus on nimesulide

    Drug Saf.

    (2002)
  • U.A. Boelsterli

    Idiosyncratic drug hepatotoxicity revisitednew insights from mechanistic toxicology

    Toxicol. Mech. Methods

    (2003)
  • U.A. Boelsterli

    Disease-related determinants of susceptibility in drug-induced hepatotoxicity

    Curr. Opin. Drug Disc. Dev.

    (2003)
  • Boelsterli, U.A., 2003c. Animal models of human disease in drug safety assessment. J. Toxicol. Sci. 28,...
  • U.A. Boelsterli et al.

    Idiosyncratic liver toxicity of nonsteroidal antiinflammatory drugsmolecular mechanisms and pathology

    Crit. Rev. Toxicol.

    (1995)
  • R. Bort et al.

    Diclofenac toxicity to hepatocytesa role for drug metabolism in cell toxicity

    J. Pharmacol. Exp. Ther.

    (1998)
  • J.P. Buchweitz et al.

    Underlying endotoxemia augments toxic responses to chlorpromazineis there a relationship to drug idiosyncrasy?

    J. Pharmacol. Exp. Ther.

    (2002)
  • S.M. Caparroz-Assef et al.

    The uncoupling effect of the nonsteroidal anti-inflammatory drug nimesulide in liver mitochondria from adjuvant-induced arthritic rats

    Cell Biochem. Funct.

    (2001)
  • J.L. Carson et al.

    Safety of nonsteroidal anti-inflammatory drugs with respect to acute liver disease

    Arch. Intern. Med.

    (1993)
  • S.D. Cohen et al.

    Acetaminophen-induced hepatotoxicity

  • M.D. Dogan et al.

    Nimesulide and diclofenac inhibit lipopolysaccharide-induced hypothermia and tumour necrosis factor-α elevation in rats

    Fundam. Clin. Pharmacol.

    (2002)
  • D.L. Eaton et al.

    Principles of toxicology

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