Nabumetone: therapeutic use and safety profile in the management of osteoarthritis and rheumatoid arthritis

Safety of the nonselective NSAID nabumetone : focus on gastrointestinal tolerability

Although effective in the treatment of pain associated with rheumatic conditions such as osteoarthritis and rheumatoid arthritis, long-term use of NSAIDs is primarily limited by their association with upper gastrointestinal (GI) toxicity. Adverse effects range from dyspepsia and abdominal pain to ulceration and bleeding. GI damage elicited by NSAIDs arises as the result of biochemically induced topical irritant effects and by topical and systemic pharmacological suppression of gastroprotective prostaglandins. Variation in the physicochemical properties and pharmacological profiles among the individual NSAIDs translate into inter-agent differences regarding propensity to cause adverse GI effects. Nabumetone is a nonselective NSAID that offers distinct advantages over other agents in this class with regard to GI tolerability. Its non-acidic nature and pro-drug formulation, together with the lack of biliary secretion of its active metabolite, 6-methoxy-2-naphthylacetic acid, are thought to contribute to the improved GI tolerability of this drug. In head-to-head trials with other NSAIDs, nabumetone has demonstrated significant benefits regarding the incidence of GI events and more serious perforations, ulcers and bleeds (PUBs). Pooled data from eight postmarketing, randomized, controlled trials demonstrated a lower cumulative frequency of PUBs with nabumetone (0.03%; 95% CI 0.0, 0.08) versus comparator NSAIDs (1.4%; 95% CI 0.5, 2.4). Large-scale database studies also indicate that risk of serious GI complications is lower with nabumetone than comparator NSAIDs. Limited comparative data suggest that nabumetone offers a GI tolerability profile similar to that of cyclo-oxygenase-2 selective NSAIDs (coxibs). Although adverse cardiovascular outcomes appear to be a class effect of the coxibs, conventional NSAIDs may also have the potential for causing atherothrombotic complications. However, based on available data, nabumetone does not appear to be associated with increased cardiovascular risk. Finally, there is no particular concern about the nephrotoxic and hepatotoxic potential of nabumetone. Nonetheless, the potential for adverse drug reactions remains, and hence nabumetone, as with any NSAID, should be used at the lowest dose, which is effective for each patient, and for the shortest time necessary to control symptoms.

Theoretical study of the phototoxicity of naproxen and the active form of nabumetone

Density functional theory using the hybrid functional B3LYP has been employed in order to study the mechanisms of photoinduced decomposition of the closely related nonsteroidal anti-inflammatory drugs naproxen (NP) and 6-methoxy-2-naphthylacetic acid (MNAA; the active form of nabumetone). The photochemical properties and computed energies of various species obtained in this study show that both drugs dominate in their deprotonated forms at physiological pH. The deprotonated acids are unable to decarboxylate from their excited singlets; instead, they decarboxylate from their first excited triplet states with high efficiency, overcoming energy barriers less than 3 and 1 kcal/mol for MNAA and NP, respectively. The ultraviolet and visible spectra of the neutral, deprotonated, and decarboxylated moieties of MNAA and NP are more-or-less similar but with higher probabilites (oscillator strength) for the latter. This fact, as well as the higher reactivity of NP, is explained in terms of the electron-donating effect of the additional methyl group present in NP. Singlet oxygen, superoxide radical anion, and corresponding peroxyl radical species are expected to be formed in different steps throughout the proposed photodegradation pathways of both drugs, which give rise to their effects on biomolecules, for example, lipid peroxidation.

Tolerability to nabumetone and meloxicam in patients with nonsteroidal anti-inflammatory drug intolerance

BACKGROUND

Because nonsteroidal anti-inflammatory drug (NSAID) intolerance depends on COX-1 inhibition, preferential or selective COX-2 inhibitors have been thought to be well tolerated by these patients.

OBJECTIVE

The aim of this study is to evaluate tolerability to nabumetone and meloxicam in patients with NSAID intolerance.

METHODS

Seventy patients intolerant to NSAIDs were selected. Thirty subjects were patients with asthma with respiratory (rhinitis-asthma) intolerance to NSAIDs (group A); 40 patients (group B) had cutaneous-mucous (urticaria-angioedema) NSAID intolerance. Diagnosis was based on clinical histories in all patients, and it was confirmed by positive single-blind placebo-controlled oral challenge test in 36 patients. After written informed consent, a single-blind placebo-controlled oral challenge test with nabumetone in all patients (2 g except for 11 patients who reached 1 g) and meloxicam (15 mg) in 51 patients was performed.

RESULTS

Of the total selected, 94.3% tolerated 1 g nabumetone. In those who reached the 2-g dose, the tolerability was 83.6%. With respect to meloxicam, 96.1% of patients, tolerated 15 mg. No significant difference in nabumetone and meloxicam tolerability was observed between groups A and B.

CONCLUSION

The results of this study confirm a high percentage of tolerability to the maximum therapeutic dosage of nabumetone and meloxicam in patients with NSAID intolerance, both in those with cutaneous/mucous manifestations and in those with respiratory disease.

CLINICAL IMPLICATIONS

Nabumetone and meloxicam are safe alternatives in NSAID-intolerant patients.

Age and rising rates of cyclooxygenase-2 inhibitor use. Results from a national survey

BACKGROUND

Cyclooxygenase-2 (COX-2) inhibitors were widely prescribed in the years following their introduction, but little is known about the frequency and context of their use across different age groups.

OBJECTIVE

To determine patterns and context of COX-2 inhibitor use in younger and older adults.

DESIGN

Cross-sectional surveys conducted each year from 1998 to 2002.

PARTICIPANTS

National Ambulatory Medical Care survey, a nationally representative sample of patient visits to community-based outpatient practices.

MEASUREMENTS

New or preexisting medication use recorded at the patient visit.

RESULTS

Cyclooxygenase-2 inhibitor use rose rapidly in all age groups, particularly in elders. By 2002, COX-2 inhibitors accounted for 67% of recorded nonsteroidal anti-inflammatory drug (NSAID) uses in visits by patients age 65 and older, compared with 33% of NSAID uses in adults age 18 to 44 and 54% in adults age 45 to 64 (P<.001). Coadministration of proton pump inhibitors or misoprostol with NSAIDs was low throughout the study period in all age groups, ranging from 6.7% of all NSAID users in 1998 (the year before COX-2 inhibitors were introduced) to 8.2% in 2002 (P=.68). For both older and younger adults, use of these gastroprotective agents occurred at similar rates among persons taking COX-2 inhibitors compared with those taking nonselective NSAIDs. Among elderly NSAID users in 2001 to 2002, elders with cardiovascular disease were more likely to receive COX-2 inhibitors than those without cardiovascular disease (86% vs 66%, P<.001).

CONCLUSIONS

Cyclooxygenase-2 inhibitors were rapidly adopted among all age groups, but particularly among the elderly, where use in patients with cardiovascular disease was especially high. Use of these agents largely supplemented, rather than replaced, older forms of gastroprotective therapy. The rapid and widespread use of COX-2 inhibitors in spite of their higher cost and potential for complications provides important lessons for physicians' approach to new and highly promoted drugs.

Biological basis for the cardiovascular consequences of COX-2 inhibition: therapeutic challenges and opportunities

Inhibitors selective for prostaglandin G/H synthase-2 (PGHS-2) (known colloquially as COX-2) were designed to minimize gastrointestinal complications of traditional NSAIDs--adverse effects attributed to suppression of COX-1-derived PGE2 and prostacyclin (PGI2). Evidence from 2 randomized controlled-outcome trials (RCTs) of 2 structurally distinct selective inhibitors of COX-2 supports this hypothesis. However, 5 RCTs of 3 structurally distinct inhibitors also indicate that such compounds elevate the risk of myocardial infarction and stroke. The clinical information is biologically plausible, as it is compatible with evidence that inhibition of COX-2-derived PGI2 removes a protective constraint on thrombogenesis, hypertension, and atherogenesis in vivo. However, the concept of simply tipping a "balance" between COX-2-derived PGI2 and COX-1-derived platelet thromboxane is misplaced. Among the questions that remain to be addressed are the following: (a) whether this hazard extends to all or some of the traditional NSAIDs; (b) whether adjuvant therapies, such as low-dose aspirin, will mitigate the hazard and if so, at what cost; (c) whether COX-2 inhibitors result in cardiovascular risk transformation during chronic dosing; and (d) how we might identify individuals most likely to benefit or suffer from such drugs in the future.