NABUMETONE
Clinical safety rating: avoid
Positive evidence of fetus risks but benefits may outweigh risks in some cases
Nonsteroidal anti-inflammatory drug (NSAID) that acts as a non-selective inhibitor of cyclooxygenase (COX-1 and COX-2), reducing prostaglandin synthesis. Its active metabolite, 6-methoxy-2-naphthylacetic acid (6MNA), is responsible for its therapeutic effects.
| Metabolism | Prodrug metabolized extensively in the liver to the active metabolite 6-methoxy-2-naphthylacetic acid (6MNA) via first-pass metabolism; primarily metabolized by CYP1A2 and CYP2C9. |
| Excretion | Approximately 80% of a dose is excreted in urine as metabolites (primarily 6-methoxy-2-naphthylacetic acid and its glucuronide conjugates), with about 10% excreted in feces. Biliary excretion is minimal. |
| Half-life | Terminal elimination half-life is approximately 22-30 hours in healthy adults, allowing once-daily dosing. Steady state is achieved after 3-5 days. |
| Protein binding | Greater than 99% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Volume of distribution is approximately 0.6-0.7 L/kg, indicating distribution into total body water and tissues. |
| Bioavailability | Oral bioavailability is absolute, as nabumetone is a prodrug completely converted to active metabolite 6-methoxy-2-naphthylacetic acid after first-pass metabolism. |
| Onset of Action | Oral: Onset of analgesic effect occurs within 1-2 hours after administration. |
| Duration of Action | Duration of analgesic and anti-inflammatory effect is approximately 24 hours with once-daily dosing, consistent with its long half-life. |
1000 mg orally once daily with food; may increase to 1500-2000 mg/day in divided doses if needed.
| Dosage form | TABLET |
| Renal impairment | GFR 30-49 mL/min: reduce dose to 50% of normal; GFR <30 mL/min: contraindicated. |
| Liver impairment | Child-Pugh Class A: no adjustment; Class B: reduce dose by 50%; Class C: contraindicated. |
| Pediatric use | Not recommended for pediatric patients as safety and efficacy have not been established. |
| Geriatric use | Use lowest effective dose, not to exceed 1000 mg/day; monitor renal function closely. |
| 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 | Nabumetone and its active metabolite 6-methoxy-2-naphthylacetic acid (6-MNA) are excreted into breast milk in low concentrations. The milk-to-plasma ratio (M/P) is not well established; limited data suggest M/P for 6-MNA is approximately 0.5-0.6. Due to the potential for adverse effects in the nursing infant (e.g., gastrointestinal bleeding, renal impairment), caution is advised. Consider using alternative analgesics such as acetaminophen or ibuprofen if breastfeeding. |
| Teratogenic Risk | NSAIDs including nabumetone are generally avoided in pregnancy, especially during the first and third trimesters. First trimester: possible increased risk of miscarriage and congenital malformations (e.g., cardiac defects) based on epidemiological data. Second trimester: considered relatively safer but should be used with caution. Third trimester (after 30 weeks): associated with premature closure of the ductus arteriosus, oligohydramnios, and fetal renal impairment; risk of neonatal complications including pulmonary hypertension and persistent pulmonary hypertension of the newborn (PPHN). |
■ FDA Black Box Warning
NSAIDs cause an increased risk of serious cardiovascular thrombotic events, including myocardial infarction and stroke, which can be fatal. This risk may increase with duration of use. Patients with cardiovascular disease or risk factors for cardiovascular disease may be at greater risk. Nabumetone is contraindicated for the treatment of perioperative pain in the setting of coronary artery bypass graft (CABG) surgery.
| Common Effects | rheumatoid arthritis |
| Serious Effects |
Hypersensitivity to nabumetone or any component of the formulation; history of asthma, urticaria, or other allergic-type reactions after taking aspirin or other NSAIDs; perioperative setting of CABG surgery; advanced renal disease; history of GI bleeding or perforation related to prior NSAID therapy; active peptic ulcer disease or GI bleeding.
| Precautions | Cardiovascular thrombotic events; gastrointestinal bleeding, ulceration, and perforation; renal toxicity; hepatic effects; hypertension; exacerbation of asthma; anemia; fluid retention and edema; serious skin reactions such as Stevens-Johnson syndrome; use in late pregnancy should be avoided. |
Loading safety data…
| Fetal Monitoring | Monitor fetal growth, amniotic fluid volume, and ductus arteriosus patency via ultrasound, especially if used in the third trimester. Monitor maternal renal function, blood pressure, and signs of gastrointestinal bleeding. In neonates exposed in utero, observe for signs of respiratory distress, persistent pulmonary hypertension, and renal dysfunction. |
| Fertility Effects | Nabumetone, like other NSAIDs, may impair female fertility by inhibiting prostaglandin synthesis, leading to delayed or disrupted ovulation. This effect is reversible upon discontinuation. Limited data on male fertility; no significant adverse effects reported. |