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Oxaprozin is a long acting nonsteroidal antiinflammatory drug (NSAID) available by prescription only which is used for therapy of chronic arthritis.  Oxaprozin has been linked to rare instances of idiosyncratic drug induced liver disease.

Oxaprozin (ox" a proe' zin) belongs to the propionic acid derivative class of NSAIDs similar to naproxen and ibuprofen.  Like other NSAIDs, oxaprozin is a potent cyclo-oxygenase (Cox-1 and -2) inhibitor which leads to decrease in synthesis of proinflammatory prostaglandins, which are potent mediators of pain and inflammatory pathways.  Oxaprozin has analgesic as well as antipyretic and antiinflammatory activities.  Because of its long half-life, oxaprozin can be given once daily.  Oxaprozin was approved in the United States in 1992 and is still widely used.  Oxaprozin is indicated for the treatment of chronic arthritis due to osteoarthritis, rheumatoid arthritis and juvenile rheumatoid arthritis.  Oxaprozin is available in tablets of 600 mg in several generic forms and under the brand name Daypro.  The recommended dose in adults is 600 to 1200 mg once daily.  As with other NSAIDs, oxaprozin is generally well tolerated, but side effects can include headache, dizziness, somnolence, dyspepsia, nausea, abdominal discomfort, heartburn, peripheral edema and hypersensitivity reactions.

Prospective studies show that up to 15% of patients taking oxaprozin chronically experience at least transient serum aminotransferase elevations.  These usually resolve even with drug continuation.  Marked aminotransferase elevations (>3 fold elevated) occur in approximately 1% of patients.


Clinically apparent liver injury with jaundice from oxaprozin is rare (~1 per 100,000 person-years of use) and it is rarely listed in large surveys of cases of drug induced liver injury.  The usual clinical presentation is an acute hepatitis-like picture arising 2 to 8 weeks after starting the medication.  The pattern of injury is typically hepatocellular, but mixed hepatocellular-cholestatic cases have been described.  Symptoms may include allergic manifestations such as fever, rash, arthralgias and facial edema.  Autoantibody formation is rare.  Liver biopsy findings are hepatocellular necrosis with prominent periportal and lobular eosinophilic infiltration suggestive of drug induced acute hepatitis.  Recovery may be delayed for several days, but is usually complete within one to two months.  At least one case of acute liver failure attributed to oxaprozin has been published.

Mechanism of Injury
The mechanism of oxaprozin hepatotoxicity is not known, but the allergic phenomena that accompany clinically apparent injury suggests an immunoallergic cause.  Rechallenge leads to rapid recurrence and should be avoided.

Outcome and Management
Severity ranges from asymptomatic elevations in serum aminotransferase levels, to symptomatic hepatitis with or without jaundice (Case 1), to acute liver failure.  Rapid improvement in symptoms and complete recovery are expected after discontinuing the medication.  Complete recovery may take several months.  Cross sensitivity to liver injury among the various NSAIDs has not been well studied or described, but in several case reports patients with oxaprozin associated hepatotoxicity had previously tolerated therapy with other propionic acid derivative NSAIDs (such as ibuprofen, naproxen or ketoprofen).  Nevertheless, patients with oxaprozin induced clinically apparent liver injury should be carefully monitored during the first few weeks of starting a different NSAID.


Drug Class:  Nonsteroidal Antiinflammatory Drugs


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Case 1.  Acute immunoallergic hepatitis due to oxaprozin.
[Modified from a case in the database of the Drug-Induced Liver Injury Network]

A 45 year old woman was given oxaprozin (1200 mg once daily) for painful “tennis elbow” (epicondylitis).  She had a past medical history of asthma and an allergic reaction to sulfonamides.  After 3 weeks of taking oxaprozin, she developed dark urine, anorexia, high fevers and right upper quadrant pain.  All of her medications were stopped, but in the next few days she developed worsening symptoms, itching and a maculopapular rash.  Physical examination revealed tenderness over the liver and spleen.  Tests for viral hepatitis and autoimmune markers were negative.  An abdominal ultrasound showed enlargement of the liver and spleen and gallstones, but no dilatation of bile ducts.  CT scan was normal.  A liver biopsy showed severe lobular hepatitis with mixed inflammatory response and numerous eosinophils.  One month after stopping oxaprozin, her symptoms had resolved and ALT and alkaline phosphatase levels had improved.  Two months after stopping, all liver tests were normal.


Key Points

Medication:Oxaprozin (500 mg daily for 14 days)
Pattern: Hepatocellular (R=7.5)
Severity: 1+ (bilirubin less than 2.5 mg%)
Latency: 3 weeks
Recovery:Rapid and complete
Other medications:Albuterol, fluticasone, ethinyl estradiol/levonorgestrel

Laboratory Values

Time After Starting Time After Stopping ALT (U/L) Alk P (U/L) Bilirubin (mg/dL) Other
Pre 20
0 Oxaprozin started
22 days 76 30 0.5 Dark urine, RUQ pain
24 days 0 242 107 0.8 Oxaprozin stopped
28 days 4 days 551 254 1.9
31 days 8 days 476 287 1.8 Rash and pruritis
35 days 12 days Liver biopsy
41 days 18 days 775 274 1.4
2 months 1 month 234 147 1.1
3 months 2 months 35 95 0.7
7 months 6 months 18 88 ...
Normal Values <42 <115 <1.2


The sudden onset of mild, but symptomatic liver disease with rash and fever within a month of starting oxaprozin suggests an allergic hepatitis-like syndrome and not merely a benign elevation in serum aminotransferase levels.  Indeed, serum ALT and bilirubin levels continued to climb and remained high for several weeks after stopping oxaprozin.  While the patient reported jaundice and dark urine, serum total bilirubin levels were never recorded to be above 2.5 mg/dL – the level typically used to define jaundice.  Liver test abnormalities returned to baseline within 2 months of onset.  In view of the allergic components of the hepatotoxicity, rechallenge is best avoided.  Interestingly, she had received naproxen (a propionic acid derivative like oxaprozin) in the past without incident, so that rechallenge with another NSAID with careful monitoring might be appropriate, particularly in view of the ubiquity of these agents and the high likelihood that she would receive one in the future.


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Clinical cases of drug-induced liver injury that have been submitted to LiverTox ("Submit a Case Report") are available for review.  Most of these reference cases are from

the Drug-Induced Liver Injury Network, but others are from users of LiverTox who have submitted data from an actual clinical case.  All cases have been reviewed and cleared

of personal identifiers and a brief comment added by the LiverTox editors.  Click on the following link to view the submitted case reports that have been made publically available.

Submitted Cases on Oxaprozin


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Oxaprozin – Generic, Daypro®


Nonsteroidal Antiinflammatory Drugs



Product labeling at DailyMed, National Library of Medicine, NIH


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Oxaprozin 21256-18-8 C18-H15-N-O3 Oxaprozin chemical structure

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References updated: 25 March 2015

  1. Zimmerman HJ. Drugs used to treat rheumatic and musculospastic disease. In, Zimmerman HJ. Hepatotoxicity: the adverse effects of drugs and other chemicals on the liver. 2nd ed. Philadelphia: Lippincott, 1999, pp. 517-553.  (Expert review of hepatotoxicity published in 1999; overt hepatitis due to oxaprozin is rare, but there have been several unreported cases of hepatocellular jaundice during oxaprozin use).

  2. Lewis JH, Stine JG. Nonsteroidal anti-inflammatory drugs and leukotriene receptor antagonists: pathology and clinical presentation of hepatotoxicity. In, Kaplowitz N, DeLeve LD, eds. Drug-induced liver disease. 3rd Edition. Amsterdam: Elsevier, 2013. pp. 370-402.  (Review of hepatotoxicity of NSAIDs mentions that overt hepatitis due to oxaprozin is rare, but two case reports have been published).

  3. Grossner T, Smyth EM, Fitzgerald GA.  Anti-inflammatory, antipyretic, and analgesic agents:  pharmacotherapy of gout. In, Brunton LL, Chabner BA, Knollman BC. Goodman & Gilman’s The pharmacological basis of therapeutics, 12th ed. New York: McGraw-Hill, 2011. p. 959-1004.  (Textbook of pharmacology and therapeutics).

  4. Janssen FW, Jusko WJ, Chiang ST, Kirkman SK, Southgate PJ, Coleman AJ, et al. Metabolism and kinetics of oxaprozin in normal subjects. Clin Pharmacol Ther 1980; 27: 352-62. PubMed Citation  (Extensive review of the pharmacokinetics of oxaprozin showing that it is well absorbed orally, metabolized by the liver, excreted in the urine and has a long serum half-life, perhaps because it is highly protein bound; long half life allows for once daily dosing).

  5. Zimmerman HJ. Hepatic effects of oxaprozin. Semin Arthritis Rheum 1986; 15: 35-42. Not in PubMed  (Classic analysis of hepatic injury in the large clinical studies of oxaprozin, reporting some degree of AST elevation in 15.4% of 1135 subjects, usually transient, mild and asymptomatic; elevations >3x ULN occurred in 12 [1.1%] patients with values 95-433 U/L, one subject developed symptoms, but no jaundice).

  6. Freeland GR, Northington RS, Hedrich DA, Walker BR. Hepatic safety of two analgesics used over the counter: ibuprofen and aspirin. Clin Pharmacol Ther 1988; 43: 473-9. PubMed Citation  (Prospective study of safety of ibuprofen, aspirin and oxaprozin in 1468 patients; AST elevations occurred in 5-15% of those on oxaprozin, 6-16% aspirin and 3% ibuprofen, but were above 3 times ULN in only 0.4-1% on oxaprozin, 5% aspirin and none ibuprofen).

  7. Miller LG. Oxaprozin: a once-daily nonsteroidal anti-inflammatory drug. Clin Pharm 1992; 11: 591-603. PubMed Citation  (Thorough summary of chemistry, pharmacology, pharmacokinetics, clinical efficacy and safety of oxaprozin based upon prelicensure studies; no new information on hepatotoxicity).

  8. Purdum PP 3rd, Shelden SL, Boyd JW, Shiffman ML. Oxaprozin-induced fulminant hepatitis. Ann Pharmacother 1994; 28: 1159-61. PubMed Citation  (56 year old woman developed jaundice 6 weeks after switching from ketoprofen to oxaprozin [bilirubin 32.1 mg/dL, ALT 4325 U/L, Alk P 335 U/L], with progressive hepatic failure and death).

  9. Weaver A, Rubin B, Caldwell J, McMahon FG, Lee D, Makarowski W, et al. Comparison of the efficacy and safety of oxaprozin and nabumetone in the treatment of patients with osteoarthritis of the knee. Clin Ther 1995; 17: 735-45. PubMed Citation  (Review of safety of oxaprozin without new information on hepatotoxicity).

  10. Manoukian AV, Carson JL. Nonsteroidal anti-inflammatory drug-induced hepatic disorders. Incidence and prevention. Drug Saf 1996; 15: 64-71. PubMed Citation  (Review of hepatotoxicity of NSAIDs, recapitulation of oxaprozin data presented by Zimmerman [1986]).

  11. Kethu SR, Rukkannagari S, Lansford CL. Oxaprozin-induced symptomatic hepatotoxicity. Ann Pharmacother 1999; 33: 942-4. PubMed Citation  (41 year old man developed jaundice 6 weeks after starting oxaprozin for shoulder pain [bilirubin 3.7 mg/dL, ALT 1950 U/L, Alk P 357 U/L], resolving within 8 weeks of stopping).

  12. Lapeyre-Mestre M, de Castro AM, Bareille MP, Garcia del Pozo J, Requejo AA, Arias LM, Montastruc J-L, et al. Non-steroidal anti-inflammatory drug-related hepatic damage in France and Spain: analysis from national spontaneous reporting systems. Fundam Clin Pharmacol 2006; 20: 391-5. PubMed Citation  (Survey of NSAID adverse drug reaction reports in Spain and France between 1982 and 2001; oxaprozin is not listed among 24 NSAIDs analyzed).

  13. Chalasani N, Fontana RJ, Bonkovsky HL, Watkins PB, Davern T, Serrano J, Yang H, Rochon J; Drug Induced Liver Injury Network (DILIN). Causes, clinical features, and outcomes from a prospective study of drug-induced liver injury in the United States. Gastroenterology 2008; 135: 1924-34. PubMed Citation  (Among 300 cases of drug induced liver disease in the US collected from 2004 to 2008, NSAIDs were implicated as a sole agent in 8 cases [4 diclofenac, 2 celecoxib, 1 meloxicam and 1 oxaprozin] and as one of several agents in 3 cases [1 diclofenac, 1 celecoxib, 1 ibuprofen]: Case 1). 

  14. Reuben A, Koch DG, Lee WM; Acute Liver Failure Study Group. Drug-induced acute liver failure: results of a U.S. multicenter, prospective study. Hepatology 2010; 52: 2065-76. PubMed Citation  (Among 1198 patients with acute liver failure enrolled in a US prospective study between 1998 and 2007, 133 were attributed to drug induced liver injury and 7 to NSAIDs, including 4 to bromfenac, 2 diclofenac and 1 etodolac, but none to oxaprozin, ibuprofen or naproxen).

  15. Bessone F. Non-steroidal anti-inflammatory drugs: What is the actual risk of liver damage? World J Gastroenterol 2010; 16: 5651-61.  PubMed Citation  (Review of estimated frequency of drug induced liver injury due to NSAIDs from large published epidemiological studies; oxaprozin not discussed).

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  1. PubMed logoRecent References on Oxaprozin

  2. Clinical Trials logoTrials on Oxaprozin

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