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PubMed1984

[Anti-inflammatory activity of a non-steroidal anti-inflammatory agent, oxaprozin, in experimental models].

Anti-inflammatory activity and mode of action of oxaprozin, a new non-steroidal anti-inflammatory agent, were investigated in experimental animal models and in vitro tests. Anti-inflammatory potency of oxaprozin was almost equal to that of aspirin in acetic acid vascular permeability, carrageenin hind paw edema, cotton pellet granuloma and adjuvant arthritis tests in rats. On the other hand, in mice, oxaprozin was more potent than aspirin, ibuprofen and phenylbutazone, and it was as potent as sulindac and fenbufen in acetic acid vascular permeability and carrageenin hind paw edema tests. In adrenalectomized rats, the anti-edema activity of oxaprozin in the carrageenin hind paw edema test was the same as that in intact rats. Oxaprozin inhibited erythema formation induced by ultra-violet rays in guinea pigs. The inhibitory potency of oxaprozin against prostaglandin E2 biosynthesis in vitro was equal to that of ibuprofen. Oxaprozin showed a concentration-dependent inhibition of heat-induced denaturation of bovine serum albumin and lysis of rabbit erythrocytes in vitro. However, oxaprozin did not inhibit rat hind paw edemas induced by dextran, formalin and serotonin. It was suggested from these results that the mode of action of oxaprozin is similar to those of other acidic non-steroidal anti-inflammatory drugs. Ulcerogenicity of oxaprozin was weaker than those of phenylbutazone and aspirin in rats. Species differences in the metabolic rate of oxaprozin were shown. The blood concentration of oxaprozin in rats is extremely low because the metabolic rate of oxaprozin is rapid in rats. Therefore, in rats, oxaprozin exhibited a weak anti-inflammatory effect. However, in mice, oxaprozin had a low metabolic rate, and the effect of oxaprozin was as potent as sulindac and fenbufen. The elimination half-life of oxaprozin is extended, 49 to 69 hr, in humans. It was suggested from these findings that oxaprozin is a potent and long acting anti-inflammatory drug in clinical use.

Animals↗
PubMed1992

Oxaprozin: a once-daily nonsteroidal anti-inflammatory drug.

The pharmacology, pharmacokinetics, clinical efficacy, adverse effects, and dosage of oxaprozin are reviewed. Oxaprozin, a nonsteroidal anti-inflammatory drug (NSAID) under consideration for approval by the Food and Drug Administration, is characterized as a propionic acid. By inhibiting cyclo-oxygenase, oxaprozin decreases the formation of prostaglandin (PG) precursors from arachidonic acid, resulting in decreased PG biosynthesis and reduced pain and inflammatory responses. Oxaprozin is well absorbed after oral administration, and peak plasma concentration is reached in three to six hours. Oxaprozin is primarily eliminated by urinary excretion of the unchanged drug. It has a long elimination half-life and persists in synovial fluid. In clinical studies, oxaprozin was equally or more effective than aspirin and as effective as naproxen in the treatment of rheumatoid arthritis. For treatment of osteoarthritis, oxaprozin was as effective as naproxen and more effective than aspirin or piroxicam. Studies have also shown oxaprozin to be effective therapy for juvenile rheumatoid arthritis and ankylosing spondylitis. Oxaprozin, like other NSAIDs, can cause gastrointestinal adverse effects. Other possible adverse effects include allergic reactions, analgesic nephropathy, hepatotoxicity, and increased bleeding times. For adults, the anticipated daily dosage is 600-1200 mg given as a single dose for rheumatoid arthritis, osteoarthritis, and analgesia. In children, oxaprozin 10-20 mg/kg/day has been used to treat juvenile rheumatoid arthritis. Oxaprozin is as effective as other NSAIDs and offers once-daily dosing; however, it does not offer any therapeutic advantage over other currently available NSAIDs.

Animals↗
PubMed1984

[The inhibitory effect of oxaprozin, a new non-steroidal anti-inflammatory drug, on platelet aggregation].

The inhibitory effects of oxaprozin, a new non-steroidal anti-inflammatory drug, on platelet aggregation and prostaglandin (PG) synthetase activity were studied. In arachidonic acid (AA)-induced rabbit platelet aggregation in vitro, oxaprozin exhibited a dose-dependent inhibitory effect, and its median inhibitory concentration was 124.2 microM. The effect of oxaprozin was less potent than that of indomethacin and piroxicam, equipotent as that of aspirin and phenylbutazone, and 2 times as potent as that of ibuprofen. In collagen-induced rat platelet aggregation ex vivo, oxaprozin showed a weak but significant inhibitory effect with oral dose of 300 mg/kg. Indomethacin, aspirin and ibuprofen exhibited an inhibitory effect with 100 mg/kg. Although phenylbutazone also exhibited an inhibitory effect with 300 mg/kg, the effect was more potent than that of oxaprozin. ADP-induced platelet aggregation both in rabbit in vitro and rat ex vivo was not affected by oxaprozin. Moreover, oxaprozin administered orally inhibited dose-dependently AA-induced pulmonary thrombotic mortality in mice, and its median effective dose was 56.4 mg/kg. The effect of oxaprozin was less potent than of sulindac, piroxicam and ibuprofen, equipotent as that of aspirin, and 5 times as potent as that of phenylbutazone. On the other hand, oxaprozin inhibited dose-dependently PG synthetase activity. The inhibitory effect of oxaprozin was less potent than that of indomethacin and piroxicam, almost equipotent as that of ibuprofen, and more potent than that of phenylbutazone and aspirin. These results suggest that oxaprozin, like many other acidic non-steroidal anti-inflammatory drugs, suppresses platelet aggregation by mainly inhibiting PG synthetase activity.

Adenosine Diphosphate↗
PubMed1986

Interaction of oxaprozin with acetaminophen, cimetidine, and ranitidine.

Twelve healthy male volunteers participated in a single-dose four-way crossover study to evaluate potential drug interactions with oxaprozin, a nonsteroidal antiinflammatory agent of the propionic class. The four modes of administration were: a. oxaprozin, 1200 mg alone; b. oxaprozin during concurrent acetaminophen, 500 mg 4 times daily; c. oxaprozin with cimetidine, 300 mg 4 times daily; d. oxaprozin with ranitidine, 150 mg every 12 hours. Acetaminophen, cimetidine, or ranitidine were begun 24 hours prior to oxaprozin dosage and continued for the 10-day duration of each trial. No significant differences existed among the four treatment conditions in peak plasma oxaprozin concentration (86 micrograms/ml), volume of distribution (0.23 l/kg), time of peak concentration (3.7 h after dosage), or elimination half-life (54 h). Oxaprozin oral clearance was significantly lower (by 20%) during both the cimetidine and ranitidine trials versus control (0.047 vs 0.047 vs 0.059 ml/min/kg), but clearance during acetaminophen was not significantly different from control. Thus acetaminophen, cimetidine or ranitidine has only a small influence on the pharmacokinetics of a single oral dose of oxaprozin. The reduction in oxaprozin clearance due to cimetidine or ranitidine is statistically significant but small in magnitude.

Acetaminophen↗
PubMed1999

Health-related quality-of-life effects of oxaprozin and nabumetone in patients with osteoarthritis of the knee.

Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly prescribed for the treatment of signs and symptoms of osteoarthritis (OA). Nabumetone and oxaprozin are 2 of the newer NSAIDs and have been shown to have similar safety and efficacy profiles. Nabumetone 1000 mg to 1500 mg once a day (QD) and oxaprozin 1200 mg QD are commonly recommended doses. This study compared the health-related quality of life (HRQOL) of patients receiving oxaprozin 1200 mg QD with that of patients receiving nabumetone 1000 mg QD or nabumetone 1500 mg QD for the treatment of signs and symptoms of OA of the knee. Two similarly designed, independent, randomized, double-masked, placebo-controlled clinical trials were conducted. In trial 1, patients were randomized to receive oxaprozin 1200 mg QD (n = 109), nabumetone 1000 mg QD (n = 110), or placebo (n = 109); in trial 2, patients received oxaprozin 1200 mg QD (n = 116), nabumetone 1500 mg QD (n = 115), or placebo (n = 116). HRQOL was measured by the Medical Outcomes Study Short-Form-36 Health Survey (1-week recall period) at baseline and weeks 2 and 6. Data from the 2 trials were combined to assess differences across the 4 groups in 8 domains and 2 summary scores at baseline, and changes in HRQOL scores at weeks 2 and 6. At week 2, the oxaprozin group showed significantly greater improvement than the placebo group in role physical, vitality, and mental component summary (MCS) scores (P < 0.05), and in physical functioning, bodily pain, social functioning, and physical component summary (PCS) scores (P < 0.01). The nabumetone 1500-mg group showed significantly greater improvement than the placebo group in bodily pain and social functioning (P < 0.05), and in vitality and MCS score (P < 0.01). No significant differences were observed between the nabumetone 1000-mg and placebo groups. At week 2, the oxaprozin group showed a greater change than the nabumetone 1000-mg group in PCS score (P < 0.05). At week 6, oxaprozin treatment resulted in significantly greater improvement than placebo in physical functioning, role physical, and bodily pain (P < 0.05); social functioning, role emotional, and mental health (P < 0.01); and vitality and MCS score (P < 0.001). The nabumetone 1500-mg group showed significantly greater responses than the placebo group in vitality (P < 0.05), mental health (P < 0.01), and MCS score (P < 0.001). The oxaprozin group had significantly better scores than the nabumetone 1500-mg group in the PCS (P < 0.05), and it showed significantly greater improvement than the nabumetone 1000 mg group in role physical and PCS score (P < 0.01) and in role emotional (P < 0.05). No statistically significant differences were found between placebo and nabumetone 1000 mg at week 6. Results of this study suggest that oxaprozin 1200 mg QD has a significant positive impact on the HRQOL of patients with OA of the knee compared with nabumetone 1000 mg QD and placebo.

Aged↗
PubMedDate not supplied

The elimination profiles of oxaprozin in equine urine and serum after a 4.8-g dose.

A method for the extraction of oxaprozin from equine urine and serum and its quantitation by high-performance liquid chromatography-ultraviolet detection is presented. Confirmation of oxaprozin in postadministration extracts was accomplished by gas chromatographic- mass spectrometric analysis of methylated extracts or liquid chromatography with tandem mass spectrometry daughter ion mass spectra of underivatized extracts. Daypro, a formulation of oxaprozin, was administered orally at a dose of 4.8 g to four standardbred mares. Urine and serum samples were collected to 120 h postadministration. Base hydrolysis of equine urine before extraction resulted in an increase in the amount of oxaprozin measured, an indication of conjugation by ester formation. The urinary elimination profiles of each horse were significantly different from each other with more than one peak in oxaprozin concentration before the 29-31-h collection time. After this collection time, the differences between the oxaprozin urinary concentrations of each horse follow each other more closely. The peak average urinary concentrations of oxaprozin were 25.1 and 17.0 microg/mL at collection times of 8-10 and 18-22 h, respectively. The latest detection of oxaprozin in urine was at the last collection time of 119-121 h postadministration at a concentration close to the detection limit of approximately 0.1 microg/mL. The serum elimination profiles do not vary between horses as much as the urinary elimination profiles. The peak average serum concentration was 49.0 microg/mL at a collection time of 6 h postadministration. The latest detection was at the last collection time of 120 h. Oxaprozin is metabolized in the horse by hydroxylation. Two major urinary metabolites were isolated and identified as hydroxylated oxaprozin. The two urinary metabolites were isolated from equine postadministration urine and analyzed by mass spectrometry and proton nuclear magnetic resonance spectroscopy, which showed that the hydroxylation had occurred at the para positions of the two aromatic rings.

Administration, Oral↗
PubMed1998

Clinical pharmacokinetics of oxaprozin.

Oxaprozin is a nonsteroidal anti-inflammatory drug which reaches peak plasma concentrations 2 to 6 hours after oral administration. Oxaprozin binds extensively, in a concentration-dependent manner, to plasma albumin. The area under the plasma concentration-time curve (AUC) of oxaprozin is linearly proportional to the dose for oral doses up to 1200 mg. At doses greater than 1200 mg there is an increase in the unbound fraction of drug, leading to an increased clearance and volume of distribution (Vd) of total oxaprozin. Accumulation of the drug at steady state is between 40 and 58% lower than predicted by single dose data. After administration of multiple doses, the apparent oral clearance (CL/F) and Vd of total oxaprozin increased while those of the unbound drug decreased significantly. Substantial concentrations of oxaprozin are attained in synovial fluid, which is a proposed site of action for nonsteroidal anti-inflammatory drugs. Relationships between total plasma, unbound plasma and synovial concentrations, and therapeutic and toxicological effects have yet to be established. Oxaprozin is eliminated following biotransformation to glucuroconjugated metabolites which are excreted in urine and bile, with little drug being eliminated unchanged. Two hydroxylated metabolites have been shown to possess anti-inflammatory activity. Hepatic disease and rheumatoid arthritis do not significantly alter the disposition of oxaprozin. Patients with renal impairment demonstrate an increase in unbound plasma concentrations of oxaprozin. A significant drug interaction has been demonstrated between oxaprozin and aspirin (acetylsalicylic acid).

Age Factors↗
PubMed1983

Effects of oxaprozin alone or in combination with aspirin on hemostasis and plasma protein binding.

Oxaprozin, a new nonsteroidal antiinflammatory agent, was studied alone and in combination with aspirin for its effects on hemostasis and protein binding in 10 healthy adults. When both oxaprozin and aspirin were given separately for seven days and in combination for five days, both drugs prolonged bleeding time and inhibited collagen- and epinephrine-induced platelet aggregation to a similar degree. The effects of the combination of oxaprozin and aspirin were not additive. The data from the protein binding study showed that oxaprozin was more than 99 per cent bound to plasma proteins. Aspirin displaced oxaprozin from its binding sites. As a result, the rate of plasma clearance of oxaprozin significantly increased from 20 to 26 ml/min/kg (P less than 0.05), and the plasma half-life decreased from 45 to 40 hours. Platelet count and the humoral clotting mechanism were not affected by either drug alone or in combination. There was no clinical evidence of bleeding. One subject who received oxaprozin for 12 days and, in addition, aspirin for the last five days developed a rash that subsided after both drugs were discontinued; one subject treated with aspirin experienced tinnitus. These data suggest that oxaprozin, like aspirin and other nonsteroidal antiinflammatory drugs, should be used with caution when administered to patients who have suffered trauma, who undergo surgery, or who have known defects in hemostasis.

Adult↗
PubMedDate not supplied

The efficacy, tolerability, and safety of 1200 mg/d of oxaprozin and 1500 mg/d of nabumetone in the treatment of patients with osteoarthritis of the knee.

This 6-week, multicenter, double-masked, placebo-controlled study compared the efficacy, tolerability, and safety of the recommended starting dose of oxaprozin (1200 mg/d) and a 1500-mg/d dose of nabumetone in the treatment of patients with moderate-to-severe osteoarthritis (OA) of the knee. A total of 347 patients with a mean age of 61.1 years were randomized to receive oxaprozin (116 patients), nabumetone (115 patients), or placebo (116 patients). Adults of either sex who were older than 18 years of age were eligible for entry into the study, if they had had OA of the knee for at least 6 months. Efficacy variables included knee pain on weight bearing, knee pain on motion, patients' and physicians' global assessments of OA, pain intensity as measured on a visual analog scale, and time to walk 50 feet as quickly as possible. Efficacy variables were assessed at baseline and at weeks 1, 2, 4, and 6. Between-group differences in efficacy variables were evident by week 1. Mean improvements were significantly greater with oxaprozin than with placebo for all efficacy variables at all time periods, except knee pain on motion at weeks 2 and 4 and time to walk 50 feet at weeks 1, 2, and 4. Mean improvements were significantly greater with nabumetone than with placebo for all efficacy variables at all time periods, except the following: knee pain on weight bearing at weeks 2, 4 and 6; knee pain on motion at weeks 2 and 4; patients' global assessment at week 4; and pain intensity as measured on a visual analog scale at weeks 2 and 4. There were, however, no significant differences between oxaprozin and nabumetone in any of these efficacy variables. Adverse events were reported by 83 (71.6%) patients who took oxaprozin, by 80 (69.6%) patients who took nabumetone, and by 57 (49.1%) patients who took placebo. Adverse events were reported for significantly more patients taking oxaprozin or nabumetone than placebo. However, adverse events tended to be mild or moderate and rarely resulted in patients withdrawing from the study. Combined with the results of an earlier study, the results of this study showed that a 1500-mg/d dose of nabumetone, which is higher than the recommended starting dose of 1000 mg/d, is required for efficacy equivalent to that of the recommended starting dose of oxaprozin, 1200 mg/d, in relieving the symptoms of OA. Thus nabumetone may require dosage titration from the recommended starting dose. Oxaprozin and nabumetone were found to have similar tolerability profiles, as shown by adverse-event monitoring and withdrawal rates, as well as clinically similar safety profiles, as demonstrated by physical examinations, hematologic and biochemical laboratory testing, hemoccult testing, and adverse-event monitoring and symptom assessment.

Adult↗
PubMed1983

Double-blind comparison of single oral doses of oxaprozin, aspirin, and placebo for relief of post-operative oral surgery pain.

The safety and efficacy of single oral doses of oxaprozin (1200 mg), aspirin (650 mg), and placebo were compared in an 8-hour double-blind study of 105 patients with moderate to severe post-operative dental-surgical pain. As measured by mean and cumulative mean scores obtained with the pain intensity and verbal pain relief scales, both active drugs produced significantly (p less than 0.05) more analgesia than did placebo. A significantly (p less than 0.05) greater proportion of patients reported effective (moderate or better) pain relief in the oxaprozin and aspirin groups than in the placebo group at 2, 3, and 4 hours; significant (p less than 0.05) differences between the oxaprozin and placebo groups continued for the entire 8 hours. Oxaprozin provided more pain relief than aspirin during the latter part of the study. There were no statistically significant differences, however, in any of the efficacy assessments between the oxaprozin and aspirin groups. By the end of the 8-hour observation, significantly (p less than 0.01) fewer patients taking oxaprozin (27%) than placebo (60%) were considered treatment failures and needed a replacement analgesic. Of those taking aspirin, 41% were treatment failures, not statistically different from the proportion of treatment failures with placebo. Adverse effects were infrequent, mild, comparable between the active treatment and placebo groups, and not definitely related to drug therapy. Oxaprozin provided greater pain relief than placebo and was comparable to aspirin during the first 4 hours of the evaluation; thereafter, greater pain relief occurred in the oxaprozin-treated group than either the aspirin or placebo-treated group.

Administration, Oral↗
PubMed1986

Oxaprozin pharmacokinetics in patients with congestive heart failure.

12 patients aged 26-71 years with stable, compensated congestive heart failure (CHF) and 12 healthy controls matched for age, sex, height, weight, and serum albumin, received a 1200-mg oral dose of the nonsteroidal antiinflammatory agent 4,5-diphenyl-2-oxazolepropionic acid (oxaprozin). Serum oxaprozin levels were measured by high pressure liquid chromatography during the next 14 days. Oxaprozin elimination half-life was not different between controls and CHF patients (63 vs 69 h), but peak serum levels were lower (79 vs 63 micrograms/ml, p less than 0.01), apparent volume of distribution was larger (0.22 vs 0.29 l/kg, p less than 0.05) and clearance tended to be higher, although not significantly so, (0.042 vs 0.053 ml/min/kg) in CHF patients. These differences might have been due to reduced serum protein binding (increased free fraction) in CHF patients (0.25 vs 0.44% unbound, p less than 0.1). After correction for individual values of free fraction, groups did not differ in peak free oxaprozin serum levels (0.20 vs 0.26 micrograms/ml), unbound volume of distribution (92 vs 83 l/kg), or unbound clearance (17.5 vs 15.0 ml/min/kg). Thus protein binding of oxaprozin in the present study was reduced in CHF due either to the underlying disease or to the concurrent medications. This in turn caused reciprocal reduction in total (free plus bound) oxaprozin levels and elevated estimates of volume of distribution and clearance. Although protein binding is altered, CHF causes no significant alteration in distribution of free oxaprozin nor free clearance of oxaprozin, which is accomplished by a combination of oxidation and conjugation.

Adult↗
PubMed1984

[The analgesic and antipyretic effects of a non-steroidal anti-inflammatory drug, oxaprozin, in experimental animals].

The analgesic and antipyretic effects of oxaprozin were investigated in comparison with those of indomethacin, ibuprofen, phenylbutazone and aspirin. On the various writhing tests in mice, the analgesic effect of oxaprozin was about 2 to 9 times more potent than those of ibuprofen, phenylbutazone and aspirin. On the other hand, the analgesic and antipyretic effects of oxaprozin in rats were roughly equivalent to those of aspirin, but less effective than those of the other drugs tested. On the urate synovitis test in dogs, only oxaprozin showed a prophylactic effect. Therefore, The effect of oxaprozin in mice and dogs was more potent than ibuprofen, phenylbutazone and aspirin. The metabolic rate of oxaprozin in rats is 3.5 and 7.2 times more rapid than in mice and dogs, respectively, and its blood level in rats is low. Moreover, the biological half-life of oxaprozin is 39 to 43 hr and 49 to 69 hr in dogs and humans, respectively. From these results, it is suggested that oxaprozin is more potent than ibuprofen, phenylbutazone and aspirin, and in clinical use, it is a long acting anti-inflammatory drug.

Analgesics↗
PubMed1997

Oxaprozin and piroxicam, nonsteroidal antiinflammatory drugs with long half-lives: effect of protein-binding differences on steady-state pharmacokinetics.

The nonsteroidal antiinflammatory drugs (NSAIDs) oxaprozin and piroxicam have long elimination half-lives (t 1/2 approximately 55 hours), permitting once-daily dose regimens. The protein-binding characteristics of these drugs, however, vary widely. This study examines the effect of these binding differences on the drugs' disposition kinetics at steady state. A total of 52 participants (26 young healthy volunteers, and 26 elderly osteoarthritic patients, 15 men and 37 women (2 of them poor metabolizers of debrisoquine [CYP2D6]) completed the two-period, two-treatment, randomized, single-dose and 21-day, once-daily multiple-dose, cross-over study. Doses of oxaprozin and piroxicam were 1,200 mg once daily and 20 mg once daily, respectively. Mean single-dose kinetic parameters of oxaprozin versus piroxicam did not differ more than +/-14% (t1/2, 53.0 versus 57.4 hours; apparent oral clearance adjusted for 70-kg body weight [Clpo], 0.139 versus 0.121 L/hr; apparent volume of distribution adjusted for 70-kg body weight [Vd/F]; 10.2 L versus 9.13 L). Protein binding was plasma-concentration dependent with oxaprozin (range, 10-400 mg/L) but not with piroxicam (range, 1-30 mg/ L). Steady-state conditions were established within 3 days with oxaprozin but took almost 12 days with piroxicam. Compared with the single-dose values, steady-state Clpo (Clpo,ss) and Vd/F of total drug increased with oxaprozin by almost 127% but remained within +/-10% with piroxicam. Post-steady-state apparent t 1/2 of the total and unbound drugs of approximately 62 hours were similarly prolonged with piroxicam but differed substantially with oxaprozin (50.6 hours [total drug] versus 23.8 hours [unbound drug]). Single dose Clpo (Clpo,sd) values of both NSAIDs were significantly correlated in the study populations. With both NSAIDs, Clpo in the two poor metabolizers of debrisoquine was within +/-20% of mean values for the population. Clinically important age- and gender-dependent decreases were not observed in the weight-adjusted, Clpo,sd or Vd/F values of the total drug for either NSAID. Clearances of the two NSAIDs were significantly correlated, suggesting that a common P450 isozyme (most likely CYP2C9, in that piroxicam is a known substrate of this isozyme) may be at least partly involved in the oxidative metabolism of these NSAIDs.

Adult↗
PubMedDate not supplied

Comparison of the efficacy and safety of oxaprozin and nabumetone in the treatment of patients with osteoarthritis of the knee.

This multicenter, 6-week, double-blind, placebo-controlled, parallel-group study compared the efficacy and safety of oxaprozin 1200 mg once daily with that of nabumetone 1000 mg once daily in patients with moderate-to-severe osteoarthritis (OA) of the knee. To be eligible, patients had to experience a flare of OA within 2 weeks of discontinuing their usual OA medication (nonsteroidal anti-inflammatory drug or analgesic). Eligible patients were assessed at baseline and then randomized to receive oxaprozin (n = 109), nabumetone (n = 110), or placebo (n = 109). Efficacy assessments were performed at weeks 1, 2, 4, and 6. Primary efficacy variables included knee pain on weight bearing, knee pain on motion, and patient's and physician's global assessments of OA. Secondary efficacy variables included pain intensity, time to walk 50 feet, and duration of morning stiffness. Safety was evaluated by use of routine laboratory analyses; physical examination at screening, baseline, and week 6 (or study termination); assessment of symptoms at baseline and at each visit; and testing stools for occult blood at screening and between week 4 and the final visit. Adverse events were monitored throughout the study. Between-group differences in efficacy variables were evident by week 1. The mean change in improvement from baseline with oxaprozin compared with placebo was statistically significant in favor of oxaprozin at weeks 1, 2, 4, and 6 for all primary efficacy variables. The mean change in improvement from baseline with nabumetone compared with placebo, however, was statistically significant only at week 1 for knee pain on motion, patient's global assessment, and physician's global assessment. The mean change in improvement from baseline was statistically significant (P < or = 0.035) in favor of oxaprozin versus nabumetone at weeks 2 and 6 for all four primary efficacy variables and also at week 4 for knee pain on motion. The incidence of adverse clinical events between treatment groups was not statistically significant. However, nine oxaprozin-treated patients had asymptomatic liver enzyme elevations reported as adverse events. Four of these patients had reversible elevations of aspartate aminotransferase and alanine aminotransferase greater than three times the upper limit of normal range (P < 0.05); two of these patients were taking other medications known to induce liver enzyme abnormalities. The study showed that oxaprozin 1200 mg once daily was statistically significantly more efficacious than nabumetone 1000 mg once daily for the treatment of patients with moderate-to-severe OA of the knee. Both drugs were clinically well tolerated.

Aged↗
PubMedDate not supplied

Economic and gastrointestinal safety comparisons of etodolac, nabumetone, and oxaprozin from insurance claims data from patients with arthritis.

This study was conducted to compare the effect of etodolac, nabumetone, and oxaprozin use on gastrointestinal (GI) safety and associated costs based on insurance claims information from practice settings. Data were obtained from a national claims database (MarketScan) for the years 1992 to 1994. The claims data of interest were for patients with arthritis who had used etodolac, nabumetone, or oxaprozin exclusively during a 9-month follow-up period (ONLY groups), or these drugs plus (PLUS groups) the other nonsteroidal anti-inflammatory drugs (NSAIDs) ibuprofen, naproxen, diclofenac, sulindac, piroxicam, ketoprofen, or indomethacin. For each group, we obtained information on the use of inpatient and outpatient services for GI-related events and the associated costs. All GI admissions were classified as NSAID-induced or possibly NSAID-induced events based on International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9 CM) codes. All outpatient upper GI ulcers or bleeding episodes were also identified by specific ICD-9 CM code. There were no significant between-group demographic differences. The proportions of patients with NSAID-induced and possibly NSAID-induced GI admissions were 0.1% and 0.4% for the etodolac-ONLY, 0.3% and 1.0% for the nabumetone-ONLY, and 0.1% and 0.5% for the oxaprozin-ONLY groups, respectively (P > 0.05), and a similar pattern was observed among the PLUS groups. In outpatient settings, 3.9%, 4.2%, and 4.9% of the etodolac-, nabumetone-, and oxaprozin-ONLY patients, respectively (P > 0.05), and 6.0%, 5.3%, and 4.7% of the etodolac-, nabumetone-, and oxaprozin-PLUS patients, respectively, had at least one upper GI ulcer/bleeding claim (P > 0.05). The total health care costs for 9 months were approximately $3000 each for the etodolac-, nabumetone-, and oxaprozin-ONLY groups. Oxaprozin, nabumetone, and etodolac had similar GI-safety and associated-costs profiles based on information from practice settings. Also, in patients who used multiple NSAIDs, the groups did not differ in their GI-safety and cost profiles.

Adult↗
PubMed1980

Metabolism and kinetics of oxaprozin in normal subjects.

Absorption, biotransformation, excretion, and kinetics of oxaprozin (4,5-diphenyl-2-oxazolepropionic acid) were examined in subjects after an oral dose of 14C-oxaprozin alone as well as before, during, and after long-term administration of unlabeled drug. A single dose of 14C-oxaprozin was rapidly absorbed and the unchanged drug was essentially the only labeled substance in plasma. Recovery of radioactivity in excreta, mostly in urine, exceeded 90%. Major biotransformation routes were glucuronidation of the carboxyl group and hydroxylation of the phenyl rings followed by glucuronidation. Administration of unlabeled oxaprozin did not affect the absorption, qualitative, or quantitative metabolite profile, or recovery of 14C-oxaprozin. Following a single dose, the kinetic parameters for 14C and unchanged drug in plasma were nearly the same. A2-compartment model with first-order elimination adequately describes kinetic disposition. The slow clearance (Clp), 0.08 to 0.12 1/hr, was almost entirely due to biotransformation and the plasma half-lifes, which ranged from 49 to 69 hr, reflected the small Clp. The small volume of distribution (VD beta = 8 to 9 1) indicates limited extravascular distribution. Multiple doses of unlabeled drug, especially when given concurrently, increased the Clp of 14C-oxaprozin. This effect is apparently related to decreased binding of high concentrations of oxaprozin to plasma protein. As a result of increased Clp, steady-state levels are only 40% of levels predicted from the single-dose study.

Adult↗
PubMed1999

Oxaprozin-induced symptomatic hepatotoxicity.

OBJECTIVE: To describe a case of symptomatic hepatotoxicity attributed to oxaprozin use. CASE SUMMARY: A 41-year-old white woman was admitted to the hospital with malaise, anorexia, and right upper quadrant pain. The patient was found to have severe jaundice with liver enzyme elevation. Laboratory test results for potential etiologies were negative, except for the use of oxaprozin for the preceding six weeks. Diagnosis of drug-induced hepatotoxicity was made by liver biopsy. The patient's symptoms resolved and liver enzymes normalized after oxaprozin was discontinued. DISCUSSION: Symptomatic hepatic effects attributable to most nonsteroidal antiinflammatory drugs (NSAIDs) are rare and usually mild. Oxaprozin has been shown to cause mild elevation of liver enzymes in clinical studies. This is the second reported case of presumed oxaprozin-induced icteric hepatitis. The mechanism of oxaprozin-induced hepatotoxicity is unclear, but is thought to be due to metabolic idiosyncrasy. Most NSAID reactions are hepatocellular and occur because of individual susceptibility (idiosyncrasy). In general, people aged >40 years and women are more predisposed to NSAID-induced liver injury. CONCLUSIONS: Although this toxicity is rare, clinicians should be aware of the potential for oxaprozin to cause hepatotoxicity and use caution when prescribing this medication. This case also stresses the importance of careful inquiry regarding drug or toxin exposure in cases of unexplained hepatitis.

Adult↗
PubMed1979

A multicentre double-blind comparison of oxaprozin aspirin therapy on rheumatoid arthritis.

Preliminary clinical studies showed that oxaprozin (4,5 Diphenyl-2-oxazolepropionic acid) has anti-inflammatory and analgesic properties with a plasma half-life of about 40 hours. Consequently, a multicentre, double-blind parallel trial was conducted for 12 weeks at thirteen investigator sites, utilizing 212 patients with classic rheumatoid arthritis and comparing oxaprozin 600 mg/day, oxaprozin 1200 mg/day and aspirin 3900 mg/day. Both the oxaprozin and aspirin-treated patients had statistically significant improvement from baseline periods, in most key categories evaluated. Oxaprozin administered twice a day (b.i.d.) was as effective as aspirin administered four times a day (q.i.d.) and caused significantly less tinnitus (p less than 0.001). Fewer patients receiving high dose oxaprozin (2%) dropped out of the study because of unsatisfactory response than did those receiving aspirin (10%). There were no clinically significant laboratory abnormalities in the gastro-intestinal, renal, hepatic or haematological parameters monitored. This study suggests that oxaprozin is effective and well tolerated in the treatment of rheumatoid arthritis.

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