Selective COX-2 inhibitors and nephrotoxicity

Localization of cyclooxygenase-2 in mice testis and assessment of its possible role through suppressing its expression using nimesulide: a preferential cyclooxygenase-2 inhibitor

Present generation non-steroidal anti-inflammatory drugs (NSAID) are potent inhibitors of the enzyme cyclooxygenase-2 (COX-2). Even though they exhibit reduced incidence of gastrotoxicity, severe nephrotoxicity and other side effects have been widely reported with respect to usage of these drugs. Since COX-2 levels are not only upregulated by inflammation but also by other stimuli such as cytokines, growth factors, mitogens and steroid hormones, we investigated the localization of COX-2 and activity of both COX-1 and COX-2 in mice testis. To correlate the localization of COX-2 with its function we suppressed COX-2 expression with the aid of nimesulide a preferential COX-2 inhibitor. We found COX-2 was constitutively expressed in the Leydig cells of mice testis suggesting a role on testosterone synthesis. Suppression of COX-2 resulted in increased concentration of most of polyunsaturated fatty acids especially arachidonic acid (AA). Prostaglandin (PG) levels which showed an initial decline during nimesulide treatment had a reversible effect during prolonged treatment. These findings state that cyclooxygenase is constitutively expressed in mice testis and continuous inhibition of COX-2 interferes in maturation of sperm.

Renal effects of etoricoxib and comparator nonsteroidal anti-inflammatory drugs in controlled clinical trials

BACKGROUND

Based on the experience with selective cyclooxygenase (COX)-2 inhibitors, including rofecoxib, valdecoxib, and celecoxib, it was anticipated that etoricoxib, a new selective COX-2 inhibitor, would display mechanism-based, dose-dependent renal adverse effects (AEs) similar to those observed with nonselective non-steroidal anti-inflammatory drugs (NSAIDs) in long-term treatment.

OBJECTIVE

The present analysis examined pooled safety data from the etoricoxib clinical development program with the aim of comparing the renal AE profiles of etoricoxib 60, 90, and 120 mg/d with those of approved therapeutic dosages of the comparator nonselective NSAIDs, naproxen 1000 mg/d and ibuprofen 2400 mg/d, and with that of placebo.

METHODS

The etoricoxib program database included data from 8 placebo-controlled Phase III studies of osteoarthritis, rheumatoid arthritis, and chronic low back pain. As part of the program-wide assessment of etoricoxib, the investigator-reported incidence of and discontinuations due to renal AEs, including hypertension, lower-extremity edema (LEE), elevated serum creatinine concentration (SCC), and congestive heart failure (CHF) were examined.

RESULTS

Data from 4770 patients were included in the analysis. Most patients were women (69.0%-80.3%), and most were white (68.0%-83.3%). The mean (SD) age at baseline ranged from 53.6 (12.1) to 62.2 (8.4) years. Overall, the incidence of renal AEs was low and generally similar between the active-treatment groups. In the placebo; etoricoxib 60-, 90-, and 120-mg; naproxen, and ibuprofen groups, the incidences of hypertension were 2.0%, 4.0%, 3.4%, 4.7%, 2.9%, and 6.6%, respectively, and the incidences of LEE were 1.9%, 3.2%, 1.5%, 1.3%, 2.3%, and 1.8%, respectively. The only significant difference found was the incidence of hypertension with etoricoxib 90 mg/d versus that with placebo (P=0.001); however, the rates of hypertension observed with etoricoxib at any dosage were not clinically meaningfully different versus comparator NSAIDs. Also, LEE was rarely of clinical significance with etoricoxib or comparator NSAIDs; related discontinuations were infrequent in all treatment groups. In addition, the incidences of elevated SCC and CHF were low among active-treatment groups (0.0% to 0.8% and 0.0% to 0.2%, respectively).

CONCLUSIONS

Based on this combined data review, the risks for renal AEs (i.e., hypertension, LEE, elevated SCC changes, and CHF) with etoricoxib 60, 90, and 120 mg/d were low, with a shallow dose response, and were generally similar to those found with the comparator NSAIDs naproxen 1000 mg/d and ibuprofen 2400 mg/d.

Adverse Drug Events Involving COX-2 Inhibitors

OBJECTIVE

To describe the types and severity of adverse drug-related events (ADEs) observed in patients receiving cyclooxygenase-2 (COX-2) inhibitors and to increase the awareness of risk factors that predispose patients to ADEs associated with COX-2 inhibitors.

METHODS

A review of ADEs reported at the University of Pittsburgh Medical Center Presbyterian Hospital (UPMC-P) revealed significant events related to use of celecoxib or rofecoxib. A query of the internal ADE database was performed to identify ADEs involving COX-2 inhibitors from January 1999 to June 2002. A similar query was performed to identify ADEs involving nonselective nonsteroidal antiinflammatory drugs (NSAIDs) reported during this same time period. Utilization data were also collected.

RESULTS

Forty-eight ADEs involving 24 patients receiving COX-2 inhibitors were reported and validated via the UPMC-P ADE review process compared with 38 events in 33 patients receiving nonselective NSAIDs. The types of ADEs reported as related to COX-2 inhibitors were similar to those reported in association with nonselective NSAIDs. Forty-two percent of ADEs (n = 20) involving COX-2 inhibitors and 45% of events (n = 17) involving nonselective NSAIDs were classified as severe. All patients receiving COX-2 inhibitors and 91% of patients receiving nonselective NSAIDs exhibited risk factors that increased their risk to experience an ADE; all but 1 of these patients were receiving outpatient COX-2 inhibitor therapy.

CONCLUSIONS

The observed ADEs involving COX-2 inhibitors were similar to those associated with nonselective NSAIDs. Most events may have been preventable, highlighting the need for education regarding the appropriate use of COX-2 inhibitors.

Risks and benefits of nonsteroidal anti-inflammatory drugs in children: a comparison with paracetamol

Nonsteroidal anti-inflammatory drugs (NSAIDs) possess antipyretic, analgesic and anti-inflammatory effects. They are frequently used in children and have numerous therapeutic indications, the most common ones being fever, postoperative pain and inflammatory disorders, such as juvenile idiopathic arthritis (JIA) and Kawasaki disease. Their major mechanism of action is through inhibition of prostaglandin biosynthesis by blockade of cyclo-oxygenase (COX). The disposition of most NSAIDs has been mainly studied in infants > or = 2 years of age. Compared with adults, the volume of distribution and clearance of NSAIDs such as diclofenac, ibuprofen (infants aged between 3 months and 2.5 years), ketorolac and nimesulide were increased in children. The elimination half-life was similar in children to that in adults. These pharmacokinetic differences might be clinically significant with the need for higher loading and/or maintenance doses in children. Ibuprofen, acetylsalicylic acid (ASA) and acetaminophen are the most frequently used agents for fever reduction in children. Over the past 20 years, because of the association between ASA use and Reye's syndrome, most of the interest has been directed toward ibuprofen and acetaminophen. In view of its comparable antipyretic efficacy, but superior tolerability profile, acetaminophen, when used appropriately with age-adapted formulations, should remain the first-line therapy in the treatment of childhood fever. At the moment, there is no scientific evidence to recommend simultaneous use of these two antipyretic drugs. Most NSAIDs provide mild to moderate analgesia, with the exception of ketorolac which has a strong analgesic activity. The analgesic efficacy of ketorolac, ketoprofen, diclofenac and ibuprofen in the treatment of postoperative pain has been mainly studied following a single dose, in children of > or = 1 year of age undergoing minor surgeries. In this setting, when used either alone or in adjunct to caudal or epidural anaesthesia, they were associated with an opioid-sparing effect and were well tolerated. With the exception of ketorolac use in children undergoing tonsillectomy, where controversy exists regarding the risk of postoperative haemorrhage, NSAIDs have not been associated with an increased risk of perioperative bleeding. NSAIDs are the first-line therapy in JIA. They appear to be equally effective and tolerated, with the exception of ASA which is associated with more adverse effects. ASA has been used for many years in the treatment of Kawasaki disease and is part of the standard modality of treatment in combination with intravenous gammaglobulins. More recently, lung inflammation associated with cystic fibrosis (CF) has become a new target for NSAIDs. Despite promising preliminary results with ibuprofen, numerous questions need to be answered before this new strategy becomes part of the conventional treatment of patients with CF. In summary, NSAIDs are effective in reducing fever, alleviating pain and reducing inflammation in children, with a good tolerance profile. Pharmacokinetic studies are needed to characterise the disposition of NSAIDs in very young infants in order to use them rationally. To date, no studies have been published on the disposition, tolerability and efficacy of specific COX-2 inhibitors in children. Further clinical experience with these agents in adults is warranted before undergoing trials with specific COX-2 inhibitors in children.

A comparison of adverse renovascular experiences among osteoarthritis patients treated with rofecoxib and comparator non-selective non-steroidal anti-inflammatory agents

BACKGROUND

Non-selective non-steroidal anti-inflammatory drugs (NSAIDs) inhibit both cyclo-oxygenase (COX) isoenzymes, i.e. COX-1 and COX-2. Rofecoxib, an agent that selectively inhibits COX-2, has been shown to provide equivalent anti-inflammatory and analgesic efficacy to comparator non-selective NSAIDs in osteoarthritis (OA) and other pain models with a significant improvement in gastrointestinal (GI) safety and tolerability. Based on renal physiology studies, it was predicted that rofecoxib would have renovascular effects similar to those observed with non-selective NSAIDs--specifically edema, blood pressure elevation, attenuation of the effects of ACE inhibitors, and (in rare circumstances), acute renal failure might be manifest in a small percentage of patients.

OBJECTIVE

To assess the renovascular safety profile of rofecoxib in OA patients compared to that of non-selective NSAID comparators.

METHODS

Renovascular adverse experiences (AEs) in over 5,000 participants in Phase IIb/III OA clinical trials were reviewed and compared between rofecoxib and non-selective NSAID comparators (ibuprofen 800mg tid, diclofenac 50 mg tid, nabumetone 1,500 mg qd).

RESULTS

The incidence of lower extremity edema (LEE) AEs was generally similar between rofecoxib 12.5 mg/day, rofecoxib 25 mg/day, and non-selective comparator NSAIDs. Treatment discontinuations due to LEE AEs and clinically significant weight gain (> or = 2 kg) associated with LEE AEs were infrequent and generally similar in all active treatment groups. Congestive heart failure (CHF) was rare in all treatment groups. The incidence of hypertension AEs was low in all active treatment groups. Discontinuations due to hypertension AEs and hypertension AEs requiring a change or adjustment in blood pressure medications were similar and uncommon in all treatment groups. There was only a single report of acute renal failure (in the ibuprofen treatment group).

CONCLUSIONS

In the rofecoxib phase IIb/III OA database, the renal safety profile for rofecoxib, a selective inhibitor of COX-2, was generally similar to that of the comparator, non-selective NSAIDs which were studied.