An analysis from clinico-epidemiological data of the principal adverse events from the COX-2 selective NSAID, nimesulide, with particular reference to hepatic injury

Involvement of mitochondria mediated pathways in hepatoprotection conferred by Fumaria parviflora Lam. extract against nimesulide induced apoptosis in vitro

Nimesulide, a popular nonsteroidal anti-inflammatory drug, has been associated with serious hepatotoxicity. Reactive oxygen species (ROS) and mitochondrial perturbations have been implicated in drug induced hepatotoxicity, although their role in the pathway needs exploration. Study was undertaken to elucidate the effect of Fumaria parviflora Lam. (Fp) on nimesulide induced cell death in primary rat hepatocyte cultures. Fp extract treated cells showed increased viability as compared to nimesulide stressed cells as assessed by MTT assay. LDH leakage increased significantly at 500microM nimesulide, and the data suggested that apoptosis was the predominant mechanism responsible for cell death. Nimesulide induced apoptosis was further confirmed by DNA fragmentation and chromatin condensation. Nimesulide exposure increased intracellular ROS, translocation of Bax and Bcl2 followed by mitochondrial depolarization and cytochrome c (Cyt c) release along with caspase-9/-3 activity confirming involvement of mitochondria in nimesulide induced apoptosis. Events like membrane depolarization of mitochondria, expression of Bax, Bcl2, externalization of phosphatidyl serine are substantially reversed by the pre-treatment of Fp extract. Thus, the study indicates that Fp extract modulates critical events regulating pro and anti-apoptotic proteins in mitochondria dependent apoptosis induced by nimesulide.

Unaltered hepatic oxidative phosphorylation and mitochondrial permeability transition in wistar rats treated with nimesulide: Relevance for nimesulide toxicity characterization

Nonsteroidal anti-inflammatory drugs have been associated with hepatotoxicity in susceptible patients. One such example is nimesulide, a preferential cyclooxygenase 2-inhibitor, widely used for the treatment of inflammation and pain. It was suggested that nimesulide could exert its hepatotoxicity by altering hepatic mitochondrial function, which was demonstrated in vitro. The objective of this study was to verify whether liver mitochondria isolated from rats treated with doses of nimesulide well above therapeutic levels possessed decreased calcium tolerance and oxidative phosphorylation, which indicates in vivo nimesulide mitochondrial toxicity. Male and female rats received nimesulide or its vehicle twice daily, for 5 days, and were killed on the seventh day for the isolation of liver mitochondria. Mitochondrial respiration, transmembrane electric potential, and calcium tolerance were characterized in all experimental groups. Nimesulide had no effect on liver mitochondrial function. Indexes of mitochondrial integrity, calcium loading capacity, and oxidative phosphorylation efficiency were unchanged between liver mitochondria from treated and control animals. In the animals tested, no evidence of degraded mitochondrial function due to nimesulide administration could be found. The results corroborate the notion that despite recognized in vitro mitochondrial toxicity, nimesulide does not cause detectable mitochondrial dysfunction in Wistar rats, even when administered in much higher concentrations than those known to have anti-inflammatory effects.

The role of COX-2 inhibitors in pain modulation

NSAIDs are the analgesics that are most commonly used world-wide. In the past few years, there have been significant advances in explaining the mechanism of action and clinical efficacy of the drugs belonging to this pharmacological family. Recent data relating to the role of cyclo-oxygenase (COX)-2 in the development of neuronal hyperexcitability and pain hypersensitivity have opened new perspectives in our understanding of the therapeutic effects of these drugs in several painful conditions. The main objective of this brief review is to deal with some physiopathological and pharmacological aspects concerning the role of NSAIDs, with special reference to COX-2 inhibitors, in the treatment of pain.

Mechanisms of NSAID-induced hepatotoxicity: focus on nimesulide

Nonsteroidal anti-inflammatory drugs (NSAIDs) have been associated with idiosyncratic hepatotoxicity in susceptible patients. The molecular mechanisms underlying this toxicity have not yet been fully elucidated. However, experimental evidence suggests that they include increased concentration of the drugs in the hepatobiliary compartment, formation of reactive metabolites that covalently modify proteins and produce oxidative stress, and mitochondrial injury. Genetic and/or acquired patient factors can either augment the pathways leading to hepatic toxicity or impede the protective and detoxifying pathways. An example is nimesulide, a selective cyclo-oxygenase-2 inhibitor widely used for the treatment of inflammatory and pain conditions, which has been recently associated with rare but serious and unpredictable adverse reactions in the liver (increases in serum aminotransferase activities, hepatocellular necrosis, and/or intrahepatic cholestasis). Similar to other drugs causing idiosyncratic hepatotoxicity, both the molecule and the patient contribute to the hazard. Here, the weakly acidic sulfonanilide drug undergoes bioreductive metabolism of the nitroarene group to reactive intermediates that have been implicated in oxidative stress, covalent binding, and mitochondrial injury. It is only in a small number of susceptible patients, however, that genetic or nongenetic factors will cause this potential toxicity to become clinically manifest. In view of the very large recipient population, the incidence of nimesulide-induced liver injury has been low (approximately 0.1 per 100,000 patients treated). Although this estimation is based on spontaneous reporting data versus sales units and needs correction due to the classical bias of this system, the type and incidence of these rare but severe hepatic adverse reactions are comparable to that of other NSAIDs.

Adverse drug reactions related to the use of NSAIDs with a focus on nimesulide: results of spontaneous reporting from a Northern Italian area

OBJECTIVE

To analyse and compare the adverse drug reactions (ADRs) associated with the use of nimesulide with those associated with diclofenac, ketoprofen, and piroxicam, reported spontaneously in a northern Italian area (Veneto and Trentino).

METHODS

Data were obtained from the spontaneous reporting system database of Veneto-Trentino, the principal contributor to the Italian spontaneous surveillance system. All case reports that occurred in association with all formulations of the nonsteroidal anti-inflammatory drugs (NSAIDs) under investigation during the period from January 1988 to December 2000, were analysed in detail. Sales data from June 1996 to May 1999 and prescription data, from 1997 to 2000 from the Veneto region were utilised to select the most widely used NSAIDs to be included in the study. The prescription data were also used to look at the drug use in relation to age.

RESULTS

During the study period, 10 608 reports describing 16 571 adverse reactions were entered into the surveillance system. We found 207 case reports for nimesulide, 187 for diclofenac, 174 for ketoprofen, and 137 for piroxicam. Analysis of sales and prescription data revealed that in the Veneto region nimesulide was the most widely prescribed drug followed at a long distance by diclofenac, piroxicam and ketoprofen. No age-related difference in the use of the four drugs was found. Analysis of the case reports revealed significantly different toxicity profiles for the four drugs. In particular, nimesulide was associated with fewer and less severe gastrointestinal (GI) ADRs compared with the other NSAIDs. Nimesulide was associated with about half the number of GI reactions (10.4%) than the other three NSAIDs (21.2% for diclofenac, 21.7% for ketoprofen, 18.6% for piroxicam). Two previously unreported reactions were also found for piroxicam and ketoprofen.

CONCLUSIONS

Nimesulide is the most frequently used NSAID in Italy. Spontaneous reporting data suggest that nimesulide has the most favourable GI tolerability profile of the NSAIDs investigated, with few reports of severe GI reactions. A few reports of hepatic and renal impairment associated with nimesulide suggest caution in patients at risk. Age-related reporting analysis suggests a higher toxicity for diclofenac and piroxicam in the elderly compared with nimesulide and ketoprofen. This analysis of the Veneto-Trentino database on spontaneous reporting confirms that NSAIDs differ in their tolerability profile, and this fact should be taken into account in the choice of drugs in relation to patient characteristics.

COX-2 inhibitors compared and contrasted

Non-steroidal anti-inflammatory drugs (NSAIDs) are the principal drug treatments for inflammation, pain and fever. They act primarily by inhibiting prostaglandin (PG) synthesis but this can cause adverse events (AEs). Since the discovery of two PG synthesising enzymes, COX-1 and COX-2, and the substantial evidence that sparing COX-1 is advantageous for gastric safety, great interest has focused on selective COX-2 inhibitors. Much of the impetus has come from the most recently developed compounds celecoxib and rofecoxib, which have shown spectacular sales growth. However, the older drugs etodolac, nimesulide and meloxicam, made before COX-2 was discovered, are also COX-1-sparing and have good GI safety and therapeutic activities. These five compounds show similarities and differences that are discussed in relation to aspects that include their uses, efficacy, actions and safety.

The ever-emerging anti-inflammatories. Have there been any real advances?

Gastrointestinal (GI) Adverse Drug Reactions (ADRs) from the NSAIDs are a major cause of morbidity and mortality in arthritic patients taking these drugs. The recent much heralded development of COX-2 selective drugs (celecoxib, rofecoxib), the objective of which has been to spare inhibition of the production of COX-1 derived mucosal protective prostaglandins, may have represented an advance in reducing the risk of serious ADRs--ulcers and bleeding--but does not appear to have reduced the incidence of symptomatic side-effects (nausea, vomiting, epigastric pain/heartburn, abdominal discomfort) which are a major reason for withdrawal from NSAID therapy, especially in the long term. The rationale of COX-2 selectivity from these newer drugs is controversial since there may be pharmacokinetic differences from established carboxylate-NSAIDs that accounts for their apparent lower ulcerogenicity. Moreover, concerns have been recently expressed that as COX-2 is important in ulcer healing, control of prostacyclin production and renal function that they may have adverse reactions from these effects. Indeed, recent reports of enhanced risk of congestive heart failure with rofecoxib are of importance and may relate to impaired prostacyclin production. Moreover, there are other therapeutic strategies that have yielded equally low ulcerogenic NSAIDs (e.g. the prodrug, nabumetone; the established COX-2 inhibitory drug, nimesulide) and even the well-established NSAIDs ibuprofen and diclofenac have relatively low upper GI ulcerogenicity and have been used as benchmark standards in comparative trials of the newer "Oxib" drugs (celecoxib, rofecoxib). Much research interest has centred on the nitric oxide-donating NSAIDs (NO-NSAIDs). The rationale for donating NSAIDs being to counteract the vasoconstriction effects of NSAIDs but this has yet to be fully evaluated. It is not certain that this "antidote" approach will be acceptable as there may also be systemic effects of the nitrobutoxyl--or other NO-donors that may have toxicological consequences. Another strategy is the development of mixed COX-5 lipoxygenase (LOX) inhibitors--the progenitors of which were benoxaprofen and BW-755C. The rationale of reducing the potential for lipoxygenase mediated actions in the stomach (e.g. vasoconstriction, leucocyte accumulation). Clearly, the need to develop newer NSAIDs with lower risks of ulcers and bleeding as well as symptomatic ADRs is still representing a major challenge.

Antipyretic effects of nimesulide, paracetamol and ibuprofen-paracetamol

The antipyretic effect of nimesulide has not been adequately compared with paracetamol and ibuprofen-paracetamol combination in children. Hence, a randomized, double blind, and parallel groups' design and multicenter study was conducted on children with respiratory tract infections. Eighty-nine patients with temperatures above 38.5 degrees C were randomly administered nimesulide (1.5 mg/kg/dose), paracetamol (10.0 mg/kg/dose), or ibuprofen-patients combination (10.0 mg/kg/dose), thrice daily for five days. The axillary temperature was recorded at the baseline and at different time intervals post administration of drugs. The hematological and biochemical investigations were performed at the basal level and at the end of the treatment period. The adverse drug reactions were monitored during the trial. All the drugs produced a significant fall in temperature as compared to their respective basal values (p < 0.001). However, on looking at the change in temperatures at different time intervals from the respective basal levels, no significant difference was found among all the drugs. Surprisingly, nimesulide had a tendency to raise serum glutamate pyruvate transaminase and serum glutamate oxaloacetate transaminase levels as compared to its baseline values. There was no marked adverse effect of the drugs on other hematological and biochemical parameters investigated. No other serious adverse reaction occurred in the study. Ibuprofen-paracetamol combination, nimesulide, and paracetamol had almost similar antipyretic effects in children.

Nimesulide: an NSAID that preferentially inhibits COX-2, and has various unique pharmacological activities

Nimesulide is a NSAID with good anti-inflammatory, analgesic and antipyretic activities expected of such compounds. However, in addition it has some unique therapeutic and pharmacological activities. The novel therapeutic aspects include a relatively low toxicity to the gastrointestinal tract and kidneys, it can be given to most patients who experience respiratory problems with other NSAIDs, and the onset of analgesia is comparatively quick. The main novel pharmacological actions obtained using nimesulide in vivo at therapeutic doses, or in vitro at concentrations within the therapeutic range of free (unbound) drug, include: a preferential inhibition of prostaglandin synthesis via COX-2, and reductions in cytokine action/release, histamine release, the release of enzymes that degrade cartilage, and the release of superoxide anions and other toxic substances from neutrophils. Interactions with other drugs are few and of little or no clinical significance.

Profile and mechanisms of gastrointestinal and other side effects of nonsteroidal anti-inflammatory drugs (NSAIDs)

The popular view that all nonsteroidal anti-inflammatory drugs (NSAIDs) act by inhibiting the production of prostaglandins has been challenged by the discovery that they also affect a wide variety of cellular processes that are important for their therapeutic actions and side effects. Although recognition of the differential activities of new and established NSAIDs on the activities of the cyclooxygenases (COXs) affecting production of inflammatory prostaglandins (from COX-2) and those that are physiologically important (from COX-1) may have significance for the prostaglandin components of the underlying inflammatory and physiologic processes, there are important features of their chemical structures that determine the various cellular and biochemical actions of these agents. Several established NSAIDs have low propensity to cause gastrointestinal (GI) ulceration and bleeding that may relate to these drugs having unique pharmacokinetic characteristics (pro-drugs, protein binding, etc). They also have weak effects on the production of GI mucosal prostaglandins and have specific physicochemical characteristics such that they cause minimal damage to mucosal membranes or effects on nonprostaglandin-related cellular mechanisms important in mucosal defenses. Some of the new COX-2-selective drugs with methyl or amino-sulfonyl moieties have relatively high pKa values and other properties that are similar to established NSAIDs with low GI ulcerogenicity. These physicochemical properties may contribute to the low irritancy of the new COX-2-selective drugs quite apart from their sparing of COX-1 in the GI mucosa. With concerns that some established NSAIDs may accelerate cartilage destruction in osteoarthritis (OA), interest is now focusing on whether the COX-2-selective drugs may have a lower potential for this adverse effect by avoiding the inhibitory effects on cartilage proteoglycan metabolism seen with such drugs as indomethacin and the salicylates. Meloxicam appears to be without inhibitory effects on proteoglycan metabolism, but it remains to be seen if this translates into any beneficial actions on the progression of joint changes in OA observed radiologically or from magnetic resonance imaging.