NAPROSYN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for NAPROSYN (NAPROSYN).
Nonsteroidal anti-inflammatory drug (NSAID) that inhibits cyclooxygenase (COX-1 and COX-2) enzymes, thereby reducing prostaglandin synthesis. This results in decreased inflammation, pain, and fever.
| Metabolism | Extensively metabolized in the liver via glucuronidation and oxidation; CYP450 involvement is minor. Major metabolite is 6-desmethylnaproxen. |
| Excretion | Renal excretion of conjugated metabolites accounts for approximately 95% of a dose, with 1-2% as unchanged naproxen. Fecal excretion is minimal (<5%). |
| Half-life | Terminal elimination half-life is 12-17 hours. This long half-life allows twice-daily dosing, but may lead to drug accumulation in elderly or renally impaired patients. |
| Protein binding | >99% bound to albumin. |
| Volume of Distribution | 0.16 L/kg (approximately 10-12 L in a 70 kg adult). Low Vd indicates distribution primarily in plasma and extracellular fluid. |
| Bioavailability | Oral: 95% (completely absorbed). Rectal: approximately 80% of oral bioavailability. |
| Onset of Action | Oral: 1-2 hours for analgesic effect. Rectal: similar to oral, 1-2 hours. |
| Duration of Action | Analgesic effect lasts up to 12 hours. Anti-inflammatory effect may persist longer with repeated dosing. |
| Molecular Weight | 230.26 |
| Action Class | NSAID's- Non-Selective COX 1&2 Inhibitors (propionic acid) |
| Brand Substitutes | Naptrox 250mg Tablet, Naprostar 250mg Tablet, Nalyxan 250mg Tablet, Naprozee 250mg Tablet, Antesvel 250mg Tablet, Xenobid Gel |
250-500 mg orally twice daily; maximum 1500 mg/day. For extended-release: 750-1000 mg orally once daily.
| Dosage form | SUSPENSION |
| Renal impairment | GFR 30-59 mL/min: decrease dose by 50% or use alternative; GFR <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 | For juvenile arthritis: 10-15 mg/kg/day divided twice daily; maximum 1000 mg/day. For other indications: 5-10 mg/kg/dose every 8-12 hours. |
| Geriatric use | Start at lowest effective dose (250 mg twice daily); monitor renal function and gastrointestinal bleeding risk. |
| 1st trimester | Avoid due to potential increased risk of miscarriage and cardiac defects; NSAIDs are not recommended. |
| 2nd trimester | Use only if clearly needed; risk of oligohydramnios and premature ductus arteriosus constriction. |
| 3rd trimester | Contraindicated after 30 weeks gestation due to risk of premature closure of ductus arteriosus and oligohydramnios. |
Clinical note
Comprehensive clinical and safety monograph for NAPROSYN (NAPROSYN).
| Placental transfer | Crosses placenta; detected in cord blood and fetal tissues. |
| Breastfeeding | Naproxen enters breast milk in small amounts; due to long half-life, avoid use while breastfeeding, especially in infants with known hypersensitivity or thrombocytopenia. |
| Lactation Rating |
■ FDA Black Box Warning
Increased risk of serious cardiovascular thrombotic events, including myocardial infarction and stroke, which can be fatal. Increased risk of serious gastrointestinal adverse events including bleeding, ulceration, and perforation, which can be fatal.
| Serious Effects |
History of aspirin or NSAID-induced asthmaActive peptic ulcer diseaseSevere renal impairment (CrCl <30 mL/min)Third trimester pregnancy (after 30 weeks)
| Precautions | Cardiovascular risk: Use lowest effective dose for shortest duration; avoid in coronary artery bypass graft surgery., Gastrointestinal risk: History of peptic ulcer disease or GI bleeding increases risk., Renal effects: May cause renal toxicity, especially in patients with impaired renal function, heart failure, or on diuretics., Hepatic effects: Elevation of liver enzymes may occur; discontinue if signs of hepatic toxicity., Anaphylactoid reactions: May occur in patients with aspirin sensitivity., Hypertension: May worsen blood pressure control., Fluid retention: Use with caution in patients with heart failure or hypertension., Hematologic effects: May inhibit platelet aggregation; monitor for bleeding. |
| Food/Dietary |
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| L3 (Moderately Safe) |
| Teratogenic Risk | First trimester: Case-control studies suggest a small increased risk of cardiac defects and oral clefts; absolute risk remains low. Second/third trimester: Exposure may cause premature constriction of the ductus arteriosus, oligohydramnios due to fetal renal effects, and risk of necrotizing enterocolitis, intracranial hemorrhage, and renal dysfunction in the neonate; avoid after 30 weeks gestation. |
| Fetal Monitoring | Monitor maternal renal function and blood pressure regularly. In third trimester, assess amniotic fluid volume (oligohydramnios). Fetal echocardiography for ductus arteriosus constriction if used beyond 30 weeks. Neonatal monitoring for bleeding, renal function, and gastrointestinal symptoms. |
| Fertility Effects | Reversible inhibition of ovulation due to effects on prostaglandin synthesis; use may impair fertility in women attempting conception, but effect ceases upon discontinuation. |
| Naproxen may be taken with food or milk to minimize gastrointestinal irritation. Avoid alcohol, as it increases the risk of stomach bleeding. No specific food restrictions beyond general NSAID precautions. |
| Clinical Pearls | Naprosyn (naproxen) is a nonsteroidal anti-inflammatory drug (NSAID) with a long half-life (~12-17 hours), allowing twice-daily dosing. Use with caution in patients with cardiovascular disease, renal impairment, or history of GI bleeding. It can mask signs of infection. Monitor renal function and blood pressure regularly. Avoid concurrent use with other NSAIDs or anticoagulants due to increased bleeding risk. Naprosyn may cause photosensitivity; advise sun protection. |
| Patient Advice | Take with food or milk to reduce stomach upset. · Do not take more than the recommended dose; overdose can cause serious side effects. · Avoid alcohol while taking this medication to lower the risk of stomach bleeding. · Tell your doctor if you have a history of stomach ulcers, high blood pressure, or kidney disease. · Watch for signs of stomach bleeding: black/tarry stools, vomit that looks like coffee grounds. · Stop taking and seek medical help if you experience chest pain, weakness, slurred speech, or shortness of breath. · Store at room temperature away from moisture and heat. · Do not combine with other products containing naproxen or other NSAIDs. |