OXAPROZIN

WARNING: RISK OF SERIOUS CARDIOVASCULAR AND GASTROINTESTINAL EVENTS Cardiovascular Thrombotic Events Nonsteroidal anti-inflammatory drugs (NSAIDs) cause an increased risk of serious cardiovascular thrombotic events, including myocardial infarction and stroke, which can be fatal. This risk may occur early in treatment and may increase with duration of use [see WARNINGS AND PRECAUTIONS (5.1)]. Oxaprozin is contraindicated in the setting of coronary artery bypass graft (CABG) surgery [see CONTRAINDICATIONS (4) and WARNINGS AND PRECAUTIONS (5.1)]. Gastrointestinal Bleeding, Ulceration, and Perforation NSAIDs cause an increased risk of serious gastrointestinal (GI) adverse events including bleeding, ulceration, and perforation of the stomach or intestines, which can be fatal. These events can occur at any time during use and without warning symptoms. Elderly patients and patients with a prior history of peptic ulcer disease and/or GI bleeding are at greater risk for serious GI events [see WARNINGS AND PRECAUTIONS (5.2)]. CLOSE

NSAIDs cause an increased risk of serious gastrointestinal (GI) adverse events including bleeding, ulceration, and perforation of the stomach or intestines, which can be fatal. These events can occur at any time during use and without warning symptoms. Elderly patients and patients with a prior history of peptic ulcer disease and/or GI bleeding are at greater risk for serious GI events [see WARNINGS AND PRECAUTIONS (5.2)].

CLOSE Oxaprozin tablets are indicated:
For relief of the signs and symptoms of osteoarthritis For relief of the signs and symptoms of rheumatoid arthritis For relief of the signs and symptoms of juvenile rheumatoid arthritis

General Dosing Instructions
Carefully consider the potential benefits and risks of oxaprozin tablets and other treatment options before deciding to use oxaprozin tablets. Use the lowest effective dosage for the shortest duration consistent with individual patient treatment goals [see WARNINGS AND PRECAUTIONS (5)].

Osteoarthritis
For OA, the dosage is 1200 mg (two 600 mg tablets) given orally once a day [see DOSAGE AND ADMINISTRATION (2.5)].

Rheumatoid Arthritis
For RA, the dosage is 1200 mg (two 600 mg tablets) given orally once a day [see DOSAGE AND ADMINISTRATION (2.5)].

Juvenile Rheumatoid Arthritis
For JRA, in patients 6 to 16 years of age, the recommended dosage given orally once per day should be based on body weight of the patient as given in Table 1 [see DOSAGE AND ADMINISTRATION (2.5)]. After observing the response to initial therapy with oxaprozin tablets, the dose and frequency should be adjusted to suit an individual patient's needs. In osteoarthritis and rheumatoid arthritis and juvenile rheumatoid arthritis, the dosage should be individualized to the lowest effective dose of oxaprozin tablets to minimize adverse effects. The maximum recommended total daily dose of oxaprozin tablets in adults is 1800 mg (26 mg/kg, whichever is lower) in divided doses. In children, doses greater than 1200 mg have not been studied.
Patients with low body weight should initiate therapy with 600 mg once daily. Patients with severe renal impairment or on dialysis should also initiate therapy with 600 mg once daily. If there is insufficient relief of symptoms in such patients, the dose may be cautiously increased to 1200 mg, but only with close monitoring [see CLINICAL PHARMACOLOGY (12.3)].
In adults, in cases where a quick onset of action is important, the pharmacokinetics of oxaprozin tablets allows therapy to be started with a one-time loading dose of 1200 mg to 1800 mg (not to exceed 26 mg/kg). Doses larger than 1200 mg/day on a chronic basis should be reserved for patients who weigh more than 50 kg, have normal renal and hepatic function, are at low risk of peptic ulcer, and whose severity of disease justifies maximal therapy. Physicians should ensure that patients are tolerating doses in the 600 mg/day to 1200 mg/day range without gastroenterologic, renal, hepatic, or dermatologic adverse effects before advancing to the larger doses. Most patients will tolerate once-a-day dosing with oxaprozin tablets, although divided doses may be tried in patients unable to tolerate single doses.
Oxaprozin tablets USP, 600 mg are supplied as white, capsule-shaped, beveled edged, biconvex, filmcoated tablets, debossed with "AA59" on one side and scored on the other side.
Oxaprozin is contraindicated in the following patients: Known hypersensitivity (e.g., anaphylactic reactions and serious skin reactions) to oxaprozin or any components of the drug product [see WARNINGS AND PRECAUTIONS (5.7,5.9)]. History of asthma, urticaria, or other allergic-type reactions after taking aspirin or other NSAIDs. Severe, sometimes fatal, anaphylactic reactions to NSAIDs have been reported in such patients [see WARNINGS AND PRECAUTIONS (5.7,5.8)]. In the setting of CABG surgery [see WARNINGS AND PRECAUTIONS (5.1)].

Cardiovascular Thrombotic Events
Clinical trials of several cyclooxygenase-2 (COX-2) selective and nonselective NSAIDs of up to three years duration have shown an increased risk of serious cardiovascular (CV) thrombotic events, including myocardial infarction (MI) and stroke, which can be fatal. Based on available data, it is unclear that the risk for CV thrombotic events is similar for all NSAIDs. The relative increase in serious CV thrombotic events over baseline conferred by NSAID use appears to be similar in those with and without known CV disease or risk factors for CV disease. However, patients with known CV disease or risk factors had a higher absolute incidence of excess serious CV thrombotic events, due to their increased baseline rate. Some observational studies found that this increased risk of serious CV thrombotic events began as early as the first weeks of treatment. The increase in CV thrombotic risk has been observed most consistently at higher doses.
To minimize the potential risk for an adverse CV event in NSAID-treated patients, use the lowest effective dose for the shortest duration possible. Physicians and patients should remain alert for the development of such events, throughout the entire treatment course, even in the absence of previous CV symptoms. Patients should be informed about the symptoms of serious CV events and the steps to take if they occur.
There is no consistent evidence that concurrent use of aspirin mitigates the increased risk of serious CV thrombotic events associated with NSAID use. The concurrent use of aspirin and an NSAID, such as oxaprozin, increases the risk of serious gastrointestinal (GI) events [see WARNINGS AND PRECAUTIONS (5.2)].

Status Post Coronary Artery Bypass Graft (CABG) Surgery
Two large, controlled clinical trials of a COX-2 selective NSAID for the treatment of pain in the first 10 to 14 days following CABG surgery found an increased incidence of myocardial infarction and stroke. NSAIDs are contraindicated in the setting of CABG [see CONTRAINDICATIONS (4)].

Post-MI Patients
Observational studies conducted in the Danish National Registry have demonstrated that patients treated with NSAIDs in the post-MI period were at increased risk of reinfarction, CV-related death, and allcause mortality beginning in the first week of treatment. In this same cohort, the incidence of death in the first year post-MI was 20 per 100 person years in NSAID-treated patients compared to 12 per 100 person years in non-NSAID exposed patients. Although the absolute rate of death declined somewhat after the first year post-MI, the increased relative risk of death in NSAID users persisted over at least the next four years of follow-up.
Avoid the use of oxaprozin in patients with a recent MI unless the benefits are expected to outweigh the risk of recurrent CV thrombotic events. If oxaprozin is used in patients with a recent MI, monitor patients for signs of cardiac ischemia.

Gastrointestinal Bleeding, Ulceration, and Perforation
NSAIDs, including oxaprozin, cause serious gastrointestinal (GI) adverse events including inflammation, bleeding, ulceration, and perforation of the esophagus, stomach, small intestine, or large intestine, which can be fatal. These serious adverse events can occur at any time, with or without warning symptoms, in patients treated with NSAIDs. Only one in five patients, who develop a serious upper GI adverse event on NSAID therapy, is symptomatic. Upper GI ulcers, gross bleeding, or perforation caused by NSAIDs occurred in approximately 1% of patients treated for 3 to 6 months, and in about 2% to 4% of patients treated for one year. However, even short-term NSAID therapy is not without risk.

Risk Factors for GI Bleeding, Ulceration, and Perforation
Patients with a prior history of peptic ulcer disease and/or GI bleeding who used NSAIDs had a greater than 10-times increased risk for developing a GI bleed compared to patients without these risk factors. Other factors that increase the risk of GI bleeding in patients treated with NSAIDs include longer duration of NSAID therapy; concomitant use of oral corticosteroids, antiplatelet drugs (such as aspirin), anticoagulants, or selective serotonin reuptake inhibitors (SSRIs); smoking; use of alcohol; older age; and poor general health status. Most postmarketing reports of fatal GI events occurred in elderly or debilitated patients. Additionally, patients with advanced liver disease and/or coagulopathy are at increased risk for GI bleeding.
Strategies to Minimize the GI Risks in NSAID-treated Patients: Use the lowest effective dosage for the shortest possible duration. Avoid administration of more than one NSAID at a time. Avoid use in patients at higher risk unless benefits are expected to outweigh the increased risk of bleeding. For such patients, as well as those with active GI bleeding, consider alternate therapies other than NSAIDs.
Remain alert for signs and symptoms of GI ulceration and bleeding during NSAID therapy. If a serious GI adverse event is suspected, promptly initiate evaluation and treatment, and discontinue oxaprozin until a serious GI adverse event is ruled out. In the setting of concomitant use of low-dose aspirin for cardiac prophylaxis, monitor patients more closely for evidence of GI bleeding [see DRUG INTERACTIONS (7)].

Hepatotoxicity
Elevations of alanine aminotransferase (ALT) or aspartate aminotransferase (AST) (three or more times the upper limit of normal [ULN]) have been reported in approximately 1% of NSAID-treated patients in clinical trials. In addition, rare, sometimes fatal, cases of severe hepatic injury, including fulminant hepatitis, liver necrosis, and hepatic failure have been reported.
Elevations of ALT or AST (less than three times ULN) may occur in up to 15% of patients treated with NSAIDs including oxaprozin.
Inform patients of the warning signs and symptoms of hepatotoxicity (e.g., nausea, fatigue, lethargy, diarrhea, pruritus, jaundice, right upper quadrant tenderness, and "flu-like" symptoms). If clinical signs and symptoms consistent with liver disease develop, or if systemic manifestations occur (e.g., eosinophilia, rash), discontinue oxaprozin immediately, and perform a clinical evaluation of the patient.

Hypertension
NSAIDs, including oxaprozin, can lead to new onset of hypertension or worsening of preexisting hypertension, either of which may contribute to the increased incidence of CV events. Patients taking angiotensin converting enzyme (ACE) inhibitors, thiazide diuretics, or loop diuretics may have impaired response to these therapies when taking NSAIDs [see DRUG INTERACTIONS (7)].
Monitor blood pressure (BP) during the initiation of NSAID treatment and throughout the course of therapy.

Heart Failure and Edema
The Coxib and traditional NSAID Trialists' Collaboration meta-analysis of randomized controlled trials demonstrated an approximately two-fold increase in hospitalizations for heart failure in COX-2 selective-treated patients and nonselective NSAID-treated patients compared to placebo-treated patients. In a Danish National Registry study of patients with heart failure, NSAID use increased the risk of MI, hospitalization for heart failure, and death.
Additionally, fluid retention and edema have been observed in some patients treated with NSAIDs. Use of oxaprozin may blunt the CV effects of several therapeutic agents used to treat these medical conditions (e.g., diuretics, ACE inhibitors, or angiotensin receptor blockers [ARBs]) [see DRUG INTERACTIONS (7)].
Avoid the use of oxaprozin in patients with severe heart failure unless the benefits are expected to outweigh the risk of worsening heart failure. If oxaprozin is used in patients with severe heart failure, monitor patients for signs of worsening heart failure.

Renal Toxicity and Hyperkalemia
Renal Toxicity Long-term administration of NSAIDs has resulted in renal papillary necrosis and other renal injury.
Renal toxicity has also been seen in patients in whom renal prostaglandins have a compensatory role in the maintenance of renal perfusion. In these patients, administration of an NSAID may cause a dosedependent reduction in prostaglandin formation and, secondarily, in renal blood flow, which may precipitate overt renal decompensation. Patients at greatest risk of this reaction are those with impaired renal function, dehydration, hypovolemia, heart failure, liver dysfunction, those taking diuretics and ACE inhibitors or ARBs, and the elderly. Discontinuation of NSAID therapy is usually followed by recovery to the pretreatment state.
No information is available from controlled clinical studies regarding the use of oxaprozin in patients with advanced renal disease. The renal effects of oxaprozin may hasten the progression of renal dysfunction in patients with preexisting renal disease.
Correct volume status in dehydrated or hypovolemic patients prior to initiating oxaprozin. Monitor renal function in patients with renal or hepatic impairment, heart failure, dehydration, or hypovolemia during use of oxaprozin [see DRUG INTERACTIONS (7)]. Avoid the use of oxaprozin in patients with advanced renal disease unless the benefits are expected to outweigh the risk of worsening renal function. If oxaprozin is used in patients with advanced renal disease, monitor patients for signs of worsening renal function.

Hyperkalemia
Increases in serum potassium concentration, including hyperkalemia, have been reported with use of NSAIDs even in some patients without renal impairment. In patients with normal renal function, these effects have been attributed to a hyporeninemic-hypoaldosteronism state.

Anaphylactic Reactions
Oxaprozin has been associated with anaphylactic reactions in patients with and without known hypersensitivity to oxaprozin and in patients with aspirin-sensitive asthma [see CONTRAINDICATIONS (4) and WARNINGS AND PRECAUTIONS (5.8)].
Seek emergency help if an anaphylactic reaction occurs.

Exacerbation of Asthma Related to Aspirin Sensitivity
A subpopulation of patients with asthma may have aspirin-sensitive asthma which may include chronic rhinosinusitis complicated by nasal polyps; severe, potentially fatal bronchospasm; and/or intolerance to aspirin and other NSAIDs. Because cross-reactivity between aspirin and other NSAIDs has been reported in such aspirin-sensitive patients, oxaprozin is contraindicated in patients with this form of aspirin sensitivity [see CONTRAINDICATIONS (4)]. When oxaprozin is used in patients with preexisting asthma (without known aspirin sensitivity), monitor patients for changes in the signs and symptoms of asthma.

Serious Skin Reactions
NSAIDs, including oxaprozin, can cause serious skin adverse reactions such as exfoliative dermatitis, Stevens-Johnson Syndrome (SJS), and toxic epidermal necrolysis (TEN), which can be fatal. These serious events may occur without warning. Inform patients about the signs and symptoms of serious skin reactions, and to discontinue the use of oxaprozin at the first appearance of skin rash or any other sign of hypersensitivity. Oxaprozin is contraindicated in patients with previous serious skin reactions to NSAIDs [see CONTRAINDICATIONS (4)].

Premature Closure of Fetal Ductus Arteriosus
Oxaprozin may cause premature closure of the fetal ductus arteriosus. Avoid use of NSAIDs, including oxaprozin, in pregnant women starting at 30 weeks of gestation (third trimester) [see USE IN SPECIFIC POPULATIONS (8.1)].

Hematologic Toxicity
Anemia has occurred in NSAID-treated patients. This may be due to occult or gross blood loss, fluid retention, or an incompletely described effect on erythropoiesis. If a patient treated with oxaprozin has any signs or symptoms of anemia, monitor hemoglobin or hematocrit.
NSAIDs, including oxaprozin, may increase the risk of bleeding events. Co-morbid conditions such as coagulation disorders or concomitant use of warfarin, other anticoagulants, antiplatelet drugs (e.g., aspirin), SSRIs, and serotonin norepinephrine reuptake inhibitors (SNRIs) may increase this risk. Monitor these patients for signs of bleeding [see DRUG INTERACTIONS (7)].

Masking of Inflammation and Fever
The pharmacological activity of oxaprozin in reducing inflammation, and possibly fever, may diminish the utility of diagnostic signs in detecting infections.

Laboratory Monitoring
Because serious GI bleeding, hepatotoxicity, and renal injury can occur without warning symptoms or signs, consider monitoring patients on long-term NSAID treatment with a complete blood count (CBC) and a chemistry profile periodically [see WARNINGS AND PRECAUTIONS (5.2, 5.3, 5.6)].

Photosensitivity
Oxaprozin has been associated with rash and/or mild photosensitivity in dermatologic testing. An increased incidence of rash on sun-exposed skin was seen in some patients in the clinical trials.

Clinical Trials Experience
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
Adverse reaction data were derived from patients who received oxaprozin in multidose, controlled, and open-label clinical trials. Rates for events from clinical trial experience are based on 2253 patients who took 1200 mg to 1800 mg oxaprozin per day in clinical trials. Of these, 1721 patients were treated for at least 1 month, 971 patients for at least 3 months, and 366 patients for more than 1 year. Incidence Greater than 1%: In clinical trials of oxaprozin or in patients taking other NSAIDs, the following adverse reactions occurred at an incidence greater than 1%.
Hematologic system: anemia, increased bleeding time.
Urogenital system: abnormal renal function, dysuria or frequency.
Incidence Greater than 1%: The following adverse reactions were reported in clinical trials or in patients taking other NSAIDs.
Body as a whole: appetite changes, death, drug hypersensitivity reactions including anaphylaxis, fever, infection, sepsis.

Postmarketing Experience
The following adverse reactions have been identified during post approval use of oxaprozin. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Body as a whole: serum sickness.
See Table 2   Oxaprozin and anticoagulants such as warfarin have a synergistic effect on bleeding. The concomitant use of oxaprozin and anticoagulants have an increased risk of serious bleeding compared to the use of either drug alone. Serotonin release by platelets plays an important role in hemostasis. Case-control and cohort epidemiological studies showed that concomitant use of drugs that interfere with serotonin reuptake and an NSAID may potentiate the risk of bleeding more than an NSAID alone.

Aspirin
Clinical Impact: Controlled clinical studies showed that the concomitant use of NSAIDs and analgesic doses of aspirin does not produce any greater therapeutic effect than the use of NSAIDs alone. In a clinical study, the concomitant use of an NSAID and aspirin was associated with a significantly increased incidence of GI adverse reactions as compared to use of the NSAID alone [see WARNINGS AND PRECAUTIONS (5.2)].

Intervention:
Concomitant use of oxaprozin and analgesic doses of aspirin is not generally recommended because of the increased risk of bleeding [see WARNINGS AND PRECAUTIONS (5.11)].
Oxaprozin is not a substitute for low dose aspirin for cardiovascular protection.

ACE Inhibitors, Angiotensin Receptor Blockers, and Beta-Blockers
Clinical Impact: NSAIDs may diminish the antihypertensive effect of ACE inhibitors, ARBs, or beta-blockers (including propranolol). In patients who are elderly, volume-depleted (including those on diuretic therapy), or have renal impairment, co-administration of an NSAID with ACE inhibitors or ARBs may result in deterioration of renal function, including possible acute renal failure. These effects are usually reversible.

Intervention:
During concomitant use of oxaprozin and ACE-inhibitors, ARBs, or beta-blockers, monitor blood pressure to ensure that the desired blood pressure is obtained. During concomitant use of oxaprozin and ACE-inhibitors or ARBs in patients who are elderly, volumedepleted, or have impaired renal function, monitor for signs of worsening renal function [see WARNINGS AND PRECAUTIONS (5.6)]. When these drugs are administered concomitantly, patients should be adequately hydrated. Assess renal function at the beginning of the concomitant treatment and periodically thereafter.

Diuretics
Clinical Impact: Clinical studies, as well as post-marketing observations, showed that NSAIDs reduced the natriuretic effect of loop diuretics (e.g., furosemide) and thiazide diuretics in some patients. This effect has been attributed to the NSAID inhibition of renal prostaglandin synthesis.

Intervention:
During concomitant use of oxaprozin with diuretics, observe patients for signs of worsening renal function, in addition to assuring diuretic efficacy including antihypertensive effects [see WARNINGS AND PRECAUTIONS (5.6)].

Digoxin
Clinical Impact: The concomitant use of oxaprozin with digoxin has been reported to increase the serum concentration and prolong the half-life of digoxin.

Intervention:
During concomitant use of oxaprozin and digoxin, monitor serum digoxin levels.

Lithium
Clinical Impact: NSAIDs have produced elevations in plasma lithium levels and reductions in renal lithium clearance. The mean minimum lithium concentration increased 15%, and the renal clearance decreased by approximately 20%. This effect has been attributed to NSAID inhibition of renal prostaglandin synthesis.

Intervention:
During concomitant use of oxaprozin and lithium, monitor patients for signs of lithium toxicity.

Methotrexate
Clinical Impact: Concomitant use of NSAIDs and methotrexate may increase the risk for methotrexate toxicity (e.g., neutropenia, thrombocytopenia, renal dysfunction) because NSAID administration may result in increased plasma levels of methotrexate, especially in patients receiving high doses of methotrexate.

Intervention:
During concomitant use of oxaprozin and methotrexate, monitor patients for methotrexate toxicity.

Cyclosporine
Clinical Impact: Concomitant use of oxaprozin and cyclosporine may increase cyclosporine's nephrotoxicity.

Intervention:
During concomitant use of oxaprozin and cyclosporine, monitor patients for signs of worsening renal function.

NSAIDs and Salicylates
Clinical Impact: Concomitant use of oxaprozin with other NSAIDs or salicylates (e.g., diflunisal, salsalate) increases the risk of GI toxicity, with little or no increase in efficacy [see WARNINGS AND PRECAUTIONS (5.2)].

Intervention:
The concomitant use of oxaprozin with other NSAIDs or salicylates is not recommended.

Pemetrexed
Clinical Impact: Concomitant use of oxaprozin and pemetrexed may increase the risk of pemetrexed-associated myelosuppression, renal, and GI toxicity (see the pemetrexed prescribing information).

Intervention:
During concomitant use of oxaprozin and pemetrexed, in patients with renal impairment whose creatinine clearance ranges from 45 to 79 mL/min, monitor for myelosuppression, renal and GI toxicity.
NSAIDs with short elimination half-lives (e.g., diclofenac, indomethacin) should be avoided for a period of two days before, the day of, and two days following administration of pemetrexed.
In the absence of data regarding potential interaction between pemetrexed and NSAIDs with longer halflives (e.g., meloxicam, nabumetone), patients taking these NSAIDs should interrupt dosing for at least five days before, the day of, and two days following pemetrexed administration.

Corticosteroids
Clinical Impact: Concomitant use of corticosteroids with oxaprozin may increase the risk of GI ulceration or bleeding.

Intervention:
Monitor patients with concomitant use of oxaprozin with corticosteroids for signs of bleeding [see WARNINGS AND PRECAUTIONS (5.2)].

Glyburide
Clinical Impact: While oxaprozin does alter the pharmacokinetics of glyburide, co-administration of oxaprozin to type II non-insulin dependent diabetic patients did not affect the area under the glucose concentration curve nor the magnitude or duration of control.

Intervention:
During concomitant use of oxaprozin and glyburide, monitor patient's blood glucose in the beginning phase of cotherapy.

Laboratory Test Interactions
False-positive urine immunoassay screening tests for benzodiazepines have been reported in patients taking oxaprozin. This is due to lack of specificity of the screening tests. False-positive test results may be expected for several days following discontinuation of oxaprozin therapy. Confirmatory tests, such as gas chromatography/mass spectrometry, will distinguish oxaprozin from benzodiazepines.

Risk Summary
Use of NSAIDs, including oxaprozin, during the third trimester of pregnancy increases the risk of premature closure of the fetal ductus arteriosus. Avoid use of NSAIDs, including oxaprozin, in pregnant women starting at 30 weeks of gestation (third trimester).
There are no adequate and well-controlled studies of oxaprozin in pregnant women.
Data from observational studies regarding potential embryofetal risks of NSAID use in women in the first or second trimesters of pregnancy are inconclusive. In the general U.S. population, all clinically recognized pregnancies, regardless of drug exposure, have a background rate of 2% to 4% for major malformations, and 15% to 20% for pregnancy loss. In animal reproduction studies, oral administration of oxaprozin to pregnant rabbits at doses 0.1-times the maximum daily human dose (based on body surface area) resulted in evidence of teratogenicity; however, oral administration of oxaprozin to pregnant mice and rats during organogenesis at doses equivalent to the maximum recommended human dose revealed no evidence of teratogenicity or embryotoxicity. In rat reproduction studies in which oxaprozin was administered through late gestation failure to deliver and a reduction in live birth index was observed at doses equivalent to the maximum recommended human dose. Based on animal data, prostaglandins have been shown to have an important role in endometrial vascular permeability, blastocyst implantation, and decidualization. In animal studies, administration of prostaglandin synthesis inhibitors such as oxaprozin, resulted in increased pre-and post-implantation loss.

Labor or Delivery
There are no studies on the effects of oxaprozin during labor or delivery. In animal studies, NSAIDS, including oxaprozin, inhibit prostaglandin synthesis, cause delayed parturition, and increase the incidence of stillbirth.

Animal data
Teratology studies with oxaprozin were performed in mice, rats, and rabbits in pregnant animals administered oral doses up to 200 mg/kg/day, 200 mg/kg/day, and 30 mg/kg/day, respectively, during the period of organogenesis. In rabbits, malformations were observed at doses greater than or equal to 7.5 mg/kg/day of oxaprozin (0.1 times the maximum recommended human daily dose [MRHD] of 1800 mg based on body surface area). However, in mice and rats, no drug-related developmental abnormalities or embryo-fetal toxicity were observed at doses up to 50 and 200 mg/kg/day of oxaprozin, respectively (0.1 times and 1.1 times the maximum recommended human daily dose of 1800 mg based on a body surface area comparison, respectively).
In fertility/reproductive studies in rats, 200 mg/kg/day oxaprozin was orally administered to female rats for 14 days prior to mating through lactation day (LD) 2, or from gestation day (GD) 15 through LD 2 and the females were mated with males treated with 200 mg/kg/day oxaprozin for 60 days prior to mating. Oxaprozin administration resulted in failure to deliver and a reduction in live birth index at 200 mg/kg/day (1.1-times the maximum recommended human daily dose of 1800 mg based on a body surface area comparison).

Risk Summary
Lactation studies have not been conducted with oxaprozin. It is not known whether oxaprozin is excreted in human milk. Oxaprozin should be administered to lactating women only if clearly indicated. The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for oxaprozin and any potential adverse effects on the breastfed infant from the oxaprozin or from the underlying maternal condition.

Females and Males of Reproductive Potential
Infertility Females Based on the mechanism of action, the use of prostaglandin-mediated NSAIDs, including oxaprozin, may delay or prevent rupture of ovarian follicles, which has been associated with reversible infertility in some women. Published animal studies have shown that administration of prostaglandin synthesis inhibitors has the potential to disrupt prostaglandin-mediated follicular rupture required for ovulation. Small studies in women treated with NSAIDs have also shown a reversible delay in ovulation. Consider withdrawal of NSAIDs, including oxaprozin, in women who have difficulties conceiving or who are undergoing investigation of infertility.

Males
Testicular degeneration was observed in beagle dogs treated with 37.5 mg/kg/day (0.7-times the maximum recommended human daily dose based on body surface area) of oxaprozin for 42 days or 6 months [see NONCLINICAL TOXICOLOGY (13.1)].

Pediatric Use
Safety and effectiveness of oxaprozin in pediatric patients below the age of 6 years of age have not been established. The effectiveness of oxaprozin for the treatment of the signs and symptoms of juvenile rheumatoid arthritis (JRA) in pediatric patients aged 6 to 16 years is supported by evidence from adequate and well controlled studies in adult rheumatoid arthritis patients, and is based on an extrapolation of the demonstrated efficacy of oxaprozin in adults with rheumatoid arthritis and the similarity in the course of the disease and the drug's mechanism of effect between these two patient populations. Use of oxaprozin in JRA patients 6 to 16 years of age is also supported by the following pediatric studies.
The pharmacokinetic profile and tolerability of oxaprozin were assessed in JRA patients relative to adult rheumatoid arthritis patients in a 14 day multiple dose pharmacokinetic study. Apparent clearance of unbound oxaprozin in JRA patients was reduced compared to adult rheumatoid arthritis patients, but this reduction could be accounted for by differences in body weight [see CLINICAL PHARMACOLOGY (12.3)]. No pharmacokinetic data are available for pediatric patients under 6 years. Adverse events were reported by approximately 45% of JRA patients versus an approximate 30% incidence of adverse events in the adult rheumatoid arthritis patient cohort. Most of the adverse events were related to the gastrointestinal tract and were mild to moderate.
In a 3 month open label study, 10 to 20 mg/kg/day of oxaprozin were administered to 59 JRA patients. Adverse events were reported by 58% of JRA patients. Most of those reported were generally mild to moderate, tolerated by the patients, and did not interfere with continuing treatment. Gastrointestinal symptoms were the most frequently reported adverse effects and occurred at a higher incidence than those historically seen in controlled studies in adults. Fifty-two patients completed 3 months of treatment with a mean daily dose of 20 mg/kg. Of 30 patients who continued treatment (19 to 48 week range total treatment duration), nine (30%) experienced rash on sun-exposed areas of the skin and 5 of those discontinued treatment. Controlled clinical trials with oxaprozin in pediatric patients have not been conducted.

Geriatric Use
Elderly patients, compared to younger patients, are at greater risk for NSAID-associated serious cardiovascular, gastrointestinal, and/or renal adverse reactions. If the anticipated benefit for the elderly patient outweighs these potential risks, start dosing at the low end of the dosing range, and monitor patients for adverse effects [see WARNINGS AND PRECAUTIONS (5.1,5.2,5.3,5.6,5.13)].
No adjustment of the dose of oxaprozin is necessary in the elderly, although many elderly may need to receive a reduced dose because of low body weight or disorders associated with aging [see CLINICAL PHARMACOLOGY (12.3)].
Of the total number of subjects evaluated in four placebo controlled clinical studies of oxaprozin, 39% were 65 and over, and 11% were 75 and over. No overall differences in safety or effectiveness were observed between these subjects and younger subjects, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out. Although selected elderly patients in controlled clinical trials tolerated oxaprozin as well as younger patients, caution should be exercised in treating the elderly.
Oxaprozin is substantially excreted by the kidney, and the risk of toxic reactions to oxaprozin may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection, and it may be useful to monitor renal function [see WARNINGS AND PRECAUTIONS (5.6)].
Symptoms following acute NSAID overdosages have been typically limited to lethargy, drowsiness, nausea, vomiting, and epigastric pain, which have been generally reversible with supportive care. Gastrointestinal bleeding has occurred. Hypertension, acute renal failure, respiratory depression, and coma have occurred, but were rare [see Warnings and Precautions (5.1,5.2,5.4,5.6)].
Manage patients with symptomatic and supportive care following an NSAID overdosage. There are no specific antidotes. Consider emesis and/or activated charcoal (60 grams to 100 grams in adults, 1 gram to 2 grams per kg of body weight in pediatric patients) and/or osmotic cathartic in symptomatic patients seen within four hours of ingestion or in patients with a large overdosage (5 to 10 times the recommended dosage). Forced diuresis, alkalinization of urine, hemodialysis, or hemoperfusion may not be useful due to high protein binding.
Oxaprozin is a nonsteroidal anti-inflammatory drug, available as tablets of 600 mg for oral administration. The chemical name is 4,5-diphenyl-2-oxazole-propionic acid. The molecular weight is 293. Its molecular formula is C18H15NO3, and it has the following chemical structure. [structure] Oxaprozin is a white to off-white powder with a slight odor and a melting point of 162°C to 163°C. It is slightly soluble in alcohol and insoluble in water, with an octanol/water partition coefficient of 4.8 at physiologic pH (7.4). The pKa in water is 4.3.

Mechanism of Action
Oxaprozin has analgesic, anti-inflammatory, and antipyretic properties.
The mechanism of action of oxaprozin, like that of other NSAIDs, is not completely understood but involves inhibition of cyclooxygenase (COX-1 and COX-2).
Oxaprozin is a potent inhibitor of prostaglandin synthesis in vitro. Oxaprozin concentrations reached during therapy have produced in vivo effects. Prostaglandins sensitize afferent nerves and potentiate the action of bradykinin in inducing pain in animal models. Prostaglandins are mediators of inflammation. Because oxaprozin is an inhibitor of prostaglandin synthesis, its mode of action may be due to a decrease of prostaglandins in peripheral tissues.

General Pharmacokinetic Characteristics
In dose proportionality studies utilizing 600 mg, 1200 mg and 1800 mg doses, the pharmacokinetics of oxaprozin in healthy subjects demonstrated nonlinear kinetics of both the total and unbound drug in opposite directions, i.e. dose exposure related increase in the clearance of total drug and decrease in the clearance of the unbound drug. Decreased clearance of the unbound drug was related predominantly to a decrease in the volume of distribution of the unbound drug and not an increase in the elimination half-life. This phenomenon is considered to have minimal impact on drug accumulation upon multiple dosing. The pharmacokinetic parameters of oxaprozin in healthy subjects receiving a single dose or multiple once-daily doses of 1200 mg are presented in Table 3.

Absorption
Oxaprozin is 95% absorbed after oral administration. Food may reduce the rate of absorption of oxaprozin, but the extent of absorption is unchanged. Antacids do not significantly affect the extent and rate of oxaprozin absorption.

Distribution
The apparent volume of distribution (Vd/F) of total oxaprozin is approximately 11 to 17 L/70 kg. Oxaprozin is 99% bound to plasma proteins, primarily to albumin. At therapeutic drug concentrations, the plasma protein binding of oxaprozin is saturable, resulting in a higher proportion of the free drug as the total drug concentration is increased. With increases in single doses or following multiple oncedaily dosing, the apparent volume of distribution and clearance of total drug increased, while that of unbound drug decreased due to the effects of nonlinear protein binding.
Oxaprozin penetrates into synovial tissues of rheumatoid arthritis patients with oxaprozin concentrations 2-fold and 3-fold greater than in plasma and synovial fluid, respectively. Oxaprozin is expected to be excreted in human milk based on its physical-chemical properties; however, the amount of oxaprozin excreted in breast milk has not been evaluated.

Elimination
Metabolism Several oxaprozin metabolites have been identified in human urine or feces.
Oxaprozin is primarily metabolized in the liver, by both microsomal oxidation (65%) and glucuronic acid conjugation (35%). Ester and ether glucuronide are the major conjugated metabolites of oxaprozin. On chronic dosing, metabolites do not accumulate in the plasma of patients with normal renal function.
Concentrations of the metabolites in plasma are very low.
Oxaprozin's metabolites do not have significant pharmacologic activity. The major ester and ether glucuronide conjugated metabolites have been evaluated along with oxaprozin in receptor binding studies and in vivo animal models and have demonstrated no activity. A small amount (<5%) of active phenolic metabolites are produced, but the contribution to overall activity is limited.

Excretion
Approximately 5% of the oxaprozin dose is excreted unchanged in the urine. Sixty-five percent (65%) of the dose is excreted in the urine and 35% in the feces as metabolites. Biliary excretion of unchanged oxaprozin is a minor pathway, and enterohepatic recycling of oxaprozin is insignificant. Upon chronic dosing, the accumulation half-life is approximately 22 hours. The elimination half-life is approximately twice the accumulation half-life due to increased binding and decreased clearance at lower concentrations.

Specific Populations
Geriatric: A multiple dose study comparing the pharmacokinetics of oxaprozin (1200 mg once daily) in 20 young (21 to 44 years) adults and 20 elderly (64 to 83 years) adults did not show any statistically significant differences between age groups.
Pediatric: A population pharmacokinetic study indicated no clinically important age dependent changes in the apparent clearance of unbound oxaprozin between adult rheumatoid arthritis patients (N=40) and juvenile rheumatoid arthritis (JRA) patients (≥6 years, N=44) when adjustments were made for differences in body weight between these patient groups. The extent of protein binding of oxaprozin at various therapeutic total plasma concentrations was also similar between the adult and pediatric patient groups. Pharmacokinetic model-based estimates of daily exposure (AUC0-24) to unbound oxaprozin in JRA patients relative to adult rheumatoid arthritis patients suggest dose to body weight range relationships, as shown in Table 4. 1Model-based nomogram derived from unbound oxaprozin steady-state plasma concentrations in JRA patients weighing 22.1 -42.7 kg or ≥45 kg administered oxaprozin 600 mg or 1200 mg once daily for 14 days, respectively.
Race: Pharmacokinetic differences due to race have not been identified.
Hepatic Impairment: Approximately 95% of oxaprozin is metabolized by the liver. However, patients with well-compensated cirrhosis do not require reduced doses of oxaprozin as compared to patients with normal hepatic function. Nevertheless, monitor patients with severe hepatic dysfunction for adverse reactions.
Renal Impairment: Oxaprozin's renal clearance decreased proportionally with creatinine clearance (CrCL), but since only approximately 5% of oxaprozin dose is excreted unchanged in the urine, the decrease in total body clearance becomes clinically important only in those subjects with highly decreased CrCL. Oxaprozin is not significantly removed from the blood in patients undergoing hemodialysis or continuous ambulatory peritoneal dialysis (CAPD) due to its high protein binding. Oxaprozin plasma protein binding may decrease in patients with severe renal deficiency. Dosage adjustment may be necessary in patients with renal insufficiency [see WARNINGS AND PRECAUTIONS (5.6)].
Cardiac Failure: Well-compensated cardiac failure does not affect the plasma protein binding or the pharmacokinetics of oxaprozin.
Drug Interaction Studies ACE inhibitors (enalapril): Oxaprozin has been shown to alter the pharmacokinetics of enalapril (significant decrease in dose-adjusted AUC0-24 and Cmax) and its active metabolite enalaprilat (significant increase in dose-adjusted AUC0-24) [see DRUG INTERACTIONS (7)].