Variability in risk of gastrointestinal complications with individual non-steroidal anti-inflammatory drugs: results of a collaborative meta-analysis

Analysis of the costs of NSAID-associated gastropathy. Experience in a US health maintenance organisation

Clinicians recognise nonsteroidal anti-inflammatory drugs (NSAIDs) as valuable first-line agents in the treatment of rheumatic disorders and as dangerous irritants to the gastrointestinal tract. This has led to questions about the economic impact of NSAID-induced gastropathy in populations. This study estimated the 1992 costs of NSAID-associated gastropathy episodes, and calculated an iatrogenic cost factor for NSAID-associated gastropathy among elderly members of a health maintenance organisation (HMO), the Northwest Region of Kaiser Permanente. Using data retrieved from automated databases and from medical records, NSAID and antiulcer drug costs were calculated, and estimates were made of the incidence rates of inpatient and outpatient NSAID-associated gastropathies, the services provided to treat them, and the cost of those services. Kaiser Permanente Northwest spent $US0.35 for each $US1.00 spent on NSAID therapy for the elderly, an iatrogenic cost factor of 1.35. The estimated average treatment per NSAID-associated gastropathy episode was $US2172. The average outpatient pharmacy cost per elderly NSAID user was $US80 and estimated average NSAID-associated treatment cost per elderly NSAID user was $US43. Although the findings were specific to the HMO because of the databases used, the methodology employed and the drug formulary influence on NSAID selection, they show that a substantial amount of resources were used to treat NSAID-induced gastropathies in the elderly, underscoring the risk of prescribing NSAIDs and reinforcing the need for their prudent use in elderly patients.

Nonsteroidal antiinflammatory drugs, ulcers and risk: a collaborative meta-analysis

Nonsteroidal antiinflammatory drugs (NSAIDs) are associated with a high prevalence of gastrointestinal toxicity. Comparisons of the risks associated with individual NSAIDs are needed, but most clinical studies in this area are not ideally suited for use in meta-analyses. These difficulties can be overcome by using strict criteria for the inclusion of studies, and by reanalyzing previous data, updated by authors where possible. In doing so, this meta-analysis compared the relative risk of serious toxicity associated with 14 NSAIDs from 12 studies with the risks of ibuprofen. These results were supported by a novel "summary ranking" analysis, which was weighted to limit the influence of smaller studies. Wide variations in relative risk among NSAIDs were observed with piroxicam and azapropazone being the most toxic. Ibuprofen was associated with the least risk, probably because of its widespread use as a low-dose analgesic. Five studies provided comparative data on NSAIDs at "high" and "low" doses (as defined in the original reports), showing that the risk of toxicity was dose related. Furthermore, at full antiinflammatory doses, the risk associated with ibuprofen was similar to that of naproxen and diclofenac. These analyses show that NSAIDs vary more in toxicity than in efficacy. First-line therapy should be started with the lowest effective dose of a less toxic NSAID, moving to higher doses or a more toxic NSAID only if the clinical situation demands it. Newer NSAIDs, such as selective cyclooxygenase-2 inhibitors, may provide safer antiinflammatory therapy.

Differentiating among nonsteroidal antiinflammatory drugs by pharmacokinetic and pharmacodynamic profiles

Cyclooxygenase (COX)-1 inhibition by nonsteroidal antiinflammatory drugs (NSAIDs) is associated with gastrointestinal and renal toxicity, while COX-2 inhibition has beneficial antiinflammatory, analgesic, and antipyretic effects. The measurement of inhibitory potency of NSAIDs on COX isoforms is strongly influenced by variations in experimental conditions in different models. The concentration of protein in the assay medium is particularly important because NSAIDs are highly protein-bound in vivo, and assays based on human whole blood provide the most suitable test system available. Of the drugs investigated in the human whole blood assay, only meloxicam showed selectivity for COX-2 at therapeutically relevant concentrations. In contrast, standard NSAIDs, such as naproxen, inhibited both COX isoforms to an equal degree at therapeutically relevant concentrations. Thus, the selectivity of NSAIDs against COX-2 relative to COX-1 may provide a means of differentiating between them according to their risk of toxicity at therapeutic doses. This may be more clinically meaningful than the traditional classification of NSAIDs based on chemical structure.

Mechanism of action of aspirin-like drugs

Nonsteroid antiinflammatory drugs (NSAIDs) or aspirin-like drugs act by inhibiting the activity of the cyclooxygenase (COX) enzyme. Two isoforms of COX exist, COX-1, which is constitutively expressed, and COX-2, which is an inducible isoform. Prostaglandins synthesized by the constitutively expressed COX-1 are implicated in the maintenance of normal physiological function and have a 'cytoprotective' action in the stomach. COX-2 expression is normally low but is induced by inflammatory stimuli and cytokines. It is thought that the antiinflammatory actions of NSAIDs are caused by the inhibition of COX-2, whereas the unwanted side effects, such as gastrointestinal and renal toxicity, are caused by the inhibition of the constitutively expressed COX-1. Individual NSAIDs show different selectivities against the COX-1 and COX-2 isoforms. NSAIDs that are selective towards COX-2, such as meloxicam, may have an improved side-effect profile over current NSAIDs. In addition to their use as antiinflammatory agents in the treatment of rheumatoid arthritis and osteoarthritis, selective COX-2 inhibitors may also be beneficial in inhibiting colorectal tumor cell growth and in delaying premature labor.

How does cystitis affect a comparative risk profile of tiaprofenic acid with other non-steroidal antiinflammatory drugs? An international study based on spontaneous reports and drug usage data. ADR Signals Analysis Project (ASAP) Team

Series of well-documented case reports strongly suggest a causal association between tiaprofenic acid and a form of aseptic cystitis, which can cause serious and long-term morbidity if the drug is not withdrawn promptly. These findings are supported in the Australian and UK spontaneous reporting data-bases. Using sales data as the denominator, a comparison of NSAIDs in the WHO drug monitoring data-base indicates that the reaction is specific to tiaprofenic acid and cannot be accounted for by changes in reporting patterns in certain countries or years. Delayed recognition is an important feature of this reaction and possible reasons for this are discussed. Comparison of the risk profiles of seven NSAIDs indicated that tiaprofenic acid had the poorest risk profile, compared with NSAIDs of similar efficacy, when cystitis reports were included. The results suggest that combining spontaneous reports, classified according to severity, with sales data may enhance the ability of drug monitoring data-bases to contribute to risk benefit appraisals.

Cyclo-oxygenase isoenzymes. How recent findings affect thinking about nonsteroidal anti-inflammatory drugs

The discovery of at least 2 cyclo-oxygenase (COX) isoenzymes, referred to as COX-1 and COX-2, has updated our knowledge of nonsteroidal anti-inflammatory drugs (NSAIDs). This has lead investigators to reconsider what can be awaited from this class of drugs. The 2 COX isoenzymes share structural and enzymatic similarities, but are specifically regulated at the molecular level and may be distinguished apart in their functions, although some physiological overlap between them does occur. The major goal in developing selective COX inhibitors is to improve NSAID tolerability. Classic NSAIDs preferentially inhibit COX-1 in vitro, but it appears hazardous to judge their gastrointestinal (GI) safety profile from these data. New compounds with a high selectivity for COX-2, especially those that are non-acidic, may be better tolerated in the GI tract. While these compounds also might have a potential use in various diseases such as colorectal cancer and neurodegenerative diseases of the Alzheimer type, the possible appearance of adverse effects, perhaps renally-related, must be taken into consideration. Finally, well-designed large clinical trials are required to adequately estimate both the promising therapeutic advantages that may be offered by highly selective NSAIDs, and the potential drawbacks that may be inherent with prolonged COX-2 inhibition.

Drug treatment of rheumatic diseases in the 1990s. Achievements and future developments

There have been several advances in the therapy of arthritis. These are based on better understanding of the pathogenesis of rheumatic diseases, re-evaluation of previous therapeutic concepts such as combination therapy, and developments within biotechnology. There are 4 main areas of development, mainly involving the treatment of inflammatory synovitis. The first is with anti-inflammatory drugs, where there has been a focus on reducing gastrointestinal toxicity through the use of combination preparations such as diclofenac-misoprostol, and the introduction of drugs with more selectivity for cyclo-oxygenase-2 inhibition such as meloxicam. An additional approach has been the development of anti-inflammatory drugs such as tenidap which also control cytokine metabolism. The second area is slow-acting antirheumatic drugs with the introduction of cyclosporin as a single agent or in combination with methotrexate, the development of immunomodulating drugs such as leflunomide, and the demonstration that some antibiotics such as minocycline have slow-acting effects. The third area is the use of corticosteroids including the development of deflazacort as a bone sparing agent, the greater use of intramuscular depot steroids and the validation of low-dose oral corticosteroids in early rheumatoid arthritis. Finally, there have been advances in the biotechnology area with the demonstration that cytokine immunotherapy such as antibodies to tumour necrosis factor can rapidly improve the symptoms of rheumatoid arthritis, and that T cell immunotherapy with antibodies to the CD4 receptor may be effective in reducing synovitis. Many of these agents have not yet been introduced into clinical practice but they show the diversity of drug development and suggest the likelihood of major therapeutic benefits in the next few years.

Meta-analysis and investigation of anti-infective therapies

Meta-analysis offers an alternative approach to examining specific sub-groups, such as classes of antibiotics, types of bacteria as well as patient groups whose response to the agent under investigation may not be equivalent. In this review, the strengths and pitfalls of meta-analyses of anti-infective therapies will be discussed.