OXAPROZIN
Clinical safety rating: avoid
Positive evidence of fetus risks but benefits may outweigh risks in some cases
Oxaprozin is a nonsteroidal anti-inflammatory drug (NSAID) that inhibits cyclooxygenase (COX-1 and COX-2) enzymes, thereby reducing prostaglandin synthesis, which results in anti-inflammatory, analgesic, and antipyretic effects.
| Metabolism | Primarily hepatic via cytochrome P450 (CYP) enzymes, including CYP2C9, with minor contributions from CYP2C8. Oxaprozin is extensively metabolized to glucuronide conjugates and other metabolites. |
| Excretion | Primarily hepatic metabolism (glucuronidation and hydroxylation) with renal excretion of metabolites; less than 1% excreted unchanged in urine; fecal elimination accounts for ~20%. |
| Half-life | Terminal elimination half-life is approximately 50–60 hours in healthy adults; clinical context: once-daily dosing achieves steady-state in 7–10 days. |
| Protein binding | 99.5% bound (primarily to albumin). |
| Volume of Distribution | 0.1–0.2 L/kg; low Vd indicates limited extravascular distribution, consistent with high protein binding. |
| Bioavailability | Oral: approximately 90%. |
| Onset of Action | Oral: 30–60 minutes; full analgesic effect may take 1–2 weeks due to cumulative anti-inflammatory action. |
| Duration of Action | Analgesic: 6–12 hours; anti-inflammatory: up to 24 hours due to long half-life; clinical note: sustained concentrations allow once-daily dosing. |
600-1200 mg orally once daily; maximum 1800 mg/day.
| Dosage form | TABLET |
| Renal impairment | CrCl 30-60 mL/min: reduce dose by 50%; CrCl <30 mL/min: contraindicated. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose by 50%; Child-Pugh C: avoid use. |
| Pediatric use | Not indicated for children <16 years; for juvenile rheumatoid arthritis: 10-20 mg/kg/day (max 1000 mg/day) in divided doses. |
| Geriatric use | Start at 600 mg/day; reduce dose by 50% in elderly with renal impairment; monitor renal function. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
ACE inhibitors and ARBs may have diminished antihypertensive effect Increases risk of serious cardiovascular thrombotic events and GI bleeding.
| Breastfeeding | Oxaprozin is excreted into breast milk in low concentrations. The milk-to-plasma concentration ratio is approximately 0.15. Although the relative infant dose is estimated to be less than 2% of the maternal weight-adjusted dose, caution is advised due to potential adverse effects on the infant's renal function and cardiovascular system. Alternatives with a shorter half-life are preferred. |
| Teratogenic Risk | Oxaprozin is a nonsteroidal anti-inflammatory drug (NSAID) that inhibits prostaglandin synthesis. Use during the first trimester is associated with an increased risk of miscarriage and congenital malformations (specifically cardiac defects and gastroschisis). During the second trimester, risks are lower but may include oligohydramnios and fetal renal dysfunction. Use in the third trimester is contraindicated due to risk of premature closure of the ductus arteriosus, oligohydramnios, neonatal renal impairment, and bleeding tendencies. Maternal NSAID use near term may prolong labor. |
■ FDA Black Box Warning
Cardiovascular risk: NSAIDs may increase the risk of serious cardiovascular thrombotic events, myocardial infarction, and stroke, which can be fatal. This risk may increase with duration of use. Patients with cardiovascular risk factors may be at greater risk. Oxaprozin is contraindicated for treatment of perioperative pain in the setting of coronary artery bypass graft (CABG) surgery. Gastrointestinal risk: NSAIDs cause an increased risk of serious gastrointestinal adverse events including bleeding, ulceration, and perforation of the stomach or intestines, which can be fatal. These events can occur at any time without warning symptoms. Elderly patients and patients with a prior history of peptic ulcer disease and/or GI bleeding are at greater risk.
| Common Effects | rheumatoid arthritis |
| Serious Effects |
["Known hypersensitivity to oxaprozin or any component of the formulation","History of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDs","Perioperative pain in the setting of CABG surgery","Active peptic ulcer disease or gastrointestinal bleeding","Advanced renal disease","Third trimester of pregnancy"]
| Precautions |
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| Fetal Monitoring | Monitor maternal renal function, blood pressure, and signs of fluid retention. Assess for oligohydramnios via ultrasound if used in the second or third trimester. Fetal echocardiography may be considered if used in the first trimester. Neonates should be monitored for respiratory status, bleeding, and renal function after in utero exposure. |
| Fertility Effects | Oxaprozin may impair female fertility by interfering with prostaglandin synthesis required for ovulation and implantation. This effect is reversible upon discontinuation. Effects on male fertility are not well established but may theoretically affect sperm function. |
| ["Cardiovascular thrombotic events","Gastrointestinal bleeding, ulceration, and perforation","Hypertension and fluid retention","Renal toxicity including papillary necrosis and renal failure","Anaphylactoid reactions","Exacerbation of asthma","Hepatic effects including elevated liver enzymes and hepatic failure","Hematologic effects including anemia and bleeding","Photosensitivity","Use in pregnancy, especially during third trimester"] |