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. |
| Molecular Weight | 293.32 |
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 | Avoid in first trimester unless potential benefit outweighs risk; associated with increased risk of spontaneous abortion and congenital malformations (e.g., cardiac septal defects) due to prostaglandin inhibition. |
| 2nd trimester | Avoid during second trimester; may cause oligohydramnios and fetal renal impairment via reduced fetal urine output. |
| 3rd trimester | Contraindicated in third trimester due to risk of premature closure of ductus arteriosus, persistent pulmonary hypertension of the newborn, oligohydramnios, and bleeding complications in both mother and neonate. |
Clinical note
ACE inhibitors and ARBs may have diminished antihypertensive effect Increases risk of serious cardiovascular thrombotic events and GI bleeding.
| Placental transfer | Oxaprozin crosses the placenta; exhibits extensive placental transfer with fetal drug levels reaching approximately 50% of maternal levels. |
| Breastfeeding |
■ 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 |
Hypersensitivity to oxaprozin or any NSAID componentHistory of asthma, urticaria, or allergic-type reactions after taking aspirin or other NSAIDsSevere uncontrolled heart failureActive gastrointestinal bleeding or peptic ulcer diseaseThird trimester of pregnancyDuring coronary artery bypass graft (CABG) surgerySevere renal impairment (eGFR <30 mL/min/1.73m²)Severe hepatic impairment (Child-Pugh Class C)
Loading safety data…
| Oxaprozin is excreted into human breast milk in low concentrations. Due to its long half-life (40-60 hours) and potential adverse effects on infant renal function and platelet aggregation, caution is advised. Use only if clearly needed and monitor infant for signs of gastrointestinal bleeding or renal impairment. |
| Lactation Rating | L3 - Moderately Safe (controversial, limited data) |
| 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. |
| 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. |
| Precautions |
| 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 |
| Food/Dietary | Oxaprozin may be taken with food or milk to minimize gastrointestinal irritation. Avoid alcohol consumption due to increased risk of GI bleeding. No specific food contraindications; however, a balanced diet is recommended during long-term therapy. Concomitant use with antacids may slightly alter absorption, but no significant interaction. |
| Clinical Pearls | Oxaprozin is a non-selective NSAID with a long half-life (~42-50 hours), allowing once-daily dosing. It is associated with higher gastrointestinal toxicity compared to some other NSAIDs; consider co-prescribing a proton pump inhibitor in high-risk patients. Peak analgesic effect may take up to 2 weeks. Monitor renal function especially in elderly, volume-depleted, or those on diuretics/ACE inhibitors. Avoid in patients with aspirin-sensitive asthma or severe hepatic impairment. |
| Patient Advice | Take with food or milk to reduce stomach upset. · Do not crush or chew tablets; swallow whole. · Avoid alcohol while taking this medication to lower GI bleeding risk. · Report black/tarry stools, vomiting blood, or severe stomach pain immediately. · May cause dizziness or drowsiness; avoid driving if affected. · Use lowest effective dose for shortest duration. · Do not take other NSAIDs or aspirin without consulting doctor. |