Relafen (nabumetone)
Last reviewed · Source: First Databank (FDB) drug data
Overview
Nabumetone is a nonsteroidal anti-inflammatory agent (NSAIA) It is a prodrug and has little pharmacologic activity until it undergoes oxidation in the liver to form an active metabolite that is structurally similar to naproxen.
Nabumetone, a naphthylalkanone derivative, is a prototypical nonsteroidal anti-inflammatory agent (NSAIA). Nabumetone is a prodrug and has little pharmacologic activity until it undergoes oxidation in the liver and forms 6-methoxy-2-naphthylacetic acid (6-MNA). This active metabolite is structurally similar to naproxen and exhibits analgesic, antipyretic, and anti-inflammatory activity partially attributed to inhibition of prostaglandin synthesis.
After oral administration, about 80% of a radiolabeled dose of nabumetone is found in the urine, suggesting significant oral absorption. Approximately 35% of a 1000 mg oral dose of nabumetone is converted to 6-MNA and 50% is converted into other metabolites. The 6-MNA metabolite is over 99% bound to plasma proteins.
The mean time to maximum plasma concentration of 6-MNA ranges from 2.5 to 4 hours, with the shorter time observed in young adults and the longer time in geriatric patients. Steady-state plasma concentrations were generally higher in geriatric patients than in young healthy subjects. Conjugation and O-demethylation are the primary mechanisms of 6-MNA metabolism.
An in vitro study evaluating the cytochrome P-450 (CYP) isoform that catalyzes 6-MNA oxidation found CYP2C9 to have the highest catalytic activity in human liver microsomes. In vitro and in vivo studies suggest that there is no evidence of enterohepatic recirculation of 6-MNA. Approximately 75% of a radiolabeled dose is recovered in urine at 48 hours and 80% in 168 hours.
About 9% is recovered in feces. The elimination half-life of 6-MNA is approximately 24 hours.
USES: See also Warning section. Nabumetone is used to reduce pain, swelling, and joint stiffness from arthritis. This medication is known as a nonsteroidal anti-inflammatory drug (NSAID).
If you are treating a chronic condition such as arthritis, ask your doctor about non-drug treatments and/or using other medications to treat your pain.
Generic name: nabumetone
Pronunciation: (nab-YOU-meh-tone)
Reference product & biosimilars
No reference, biosimilar or interchangeable associated with this drug.
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Indications
The following indications are listed for Relafen:
- Osteoarthritis
- Rheumatoid Arthritis
Also known as: Arthritis Deformans, Arthrosis Deformans, Degenerative Arthritis, Degenerative Joint Disease, Degenerative Polyarthritis, Hypertrophic Arthritis, Nodose Rheumatism, Osteoarthrosis, Rheumatic Arthritis, Rheumatic Gout.
Dosing
No dosing information is available for this tab.
Nabumetone is administered orally. It is available as a tablet and may be administered without regard to meals.
Store tablets at 20-25degreesC; excursions permitted between 15-30degreesC for the generic tablets.
No dosing information is available for this tab.
No dosing information is available for this tab.
Drug interactions
Nabumetone and its active metabolite, 6-methoxy-2-naphthylacetic acid (6-MNA), undergo hepatic biotransformation via conjugation and O-demethylation. In vitro studies suggest that the cytochrome P-450 (CYP) isoenzyme 2C9 is involved in the metabolism of 6-MNA. In vitro studies have shown that 6-MNA may displace other protein-bound drugs from their binding site.
No information is available indicating nabumetone or its metabolites inhibit microsomal enzymes or transporter proteins.
There are no contraindication interactions for this drug.
There are no severe interactions for this drug.
There are no moderate interactions for this drug.
Contraindications
*Known hypersensitivity to the drug or any ingredient in the formulation.
*History of asthma, urticaria, or other sensitivity reactions after taking aspirin or other nonsteroidal anti-inflammatory agents (NSAIAs).
*Setting of coronary artery bypass graft (CABG) surgery.
There are no contraindication contraindications for this drug.
There are no severe contraindications for this drug.
There are no moderate contraindications for this drug.
Adverse reactions
Adverse effects reported in >3% of patients receiving nabumetone in clinical trials include diarrhea, dyspepsia, abdominal pain, constipation, flatulence, nausea, positive stool guaiac, dizziness, headache, pruritus, rash, tinnitus, and edema.
There are no severe adverse reactions for this drug.
There are no less severe adverse reactions for this drug.
Precautions
No enhanced messaging available.
Safety and effectiveness in pediatric patients have not been established.
Use of NSAIAs, including nabumetone, during pregnancy at about 30 weeks' gestation or later increases the risk of premature closure of the fetal ductus arteriosus. NSAIA use at about 20 weeks' gestation or later has been associated with fetal renal dysfunction resulting in oligohydramnios and, in some cases, neonatal renal impairment.
Oligohydramnios or neonatal renal impairment has occurred, on average, after days to weeks of treatment. Infrequently, oligohydramnios has been reported as soon as 48 hours after initiation. The decrease in amniotic fluid is generally transient in most, but not all, cases, and is reversible upon cessation of the drug. A limited number of case reports describe maternal NSAIA use and irreversible neonatal dysfunction without oligohydramnios. Some cases required invasive procedures, such as exchange transfusion or dialysis. A reliable estimate of the risk of adverse fetal and neonatal outcomes with maternal NSAIA use is unknown due to the inherent limitations of postmarketing studies and reports. Because the published safety data on neonatal outcomes involved mostly preterm infants, the generalizability of certain reported risks to the full-term infant exposed to NSAIAs through maternal use is uncertain.
Observational data regarding other embryofetal risks with NSAIAs during the first or second trimester of pregnancy are inconclusive. Animal data indicate that prostaglandins have an important role in endometrial vascular permeability, blastocyst implantation, and decidualization. In animal studies, inhibitors of prostaglandin synthesis, such as nabumetone, resulted in increased pre- and post-implantation loss. Prostaglandins also have an important role in fetal kidney development. In animal studies, inhibitors of prostaglandin synthesis have been reported to impair kidney development at clinically relevant doses.
Nabumetone should be used in pregnancy only if the potential benefit justifies the potential fetal risk. If used, limit the dose and duration of nabumetone use between 20 and 30 weeks' gestation. Avoid nabumetone use at about 30 weeks' gestation and later in pregnancy.
The effects of nabumetone on labor and delivery are unknown. In animal studies with NSAIAs, an increased incidence of dystocia, delayed parturition, and decreased pup survival occurred.
The distribution of nabumetone in human milk is unknown. The presence of 6-methoxy-2- naphthylacetic acid (6-MNA) has been detected in the milk of lactating rats. Due to the potential for serious adverse reactions in nursing infants from nabumetone, discontinue nursing or discontinue the drug, taking into account the importance of the drug to the mother.
The manufacturer makes no recommendation for dosage adjustment in geriatric patients; however, increased monitoring for adverse effects is advised in this population.
Of the 1677 patients treated with nabumetone in clinical studies, 411 patients (24%) were 65 years or older; 22 patients (1%) were 75 years or older. No overall differences in efficacy or safety were observed between older and younger patients. Similar results were observed in a 1-year, non-US postmarketing surveillance study of 10,800 patients treated with nabumetone, of whom 4577 (42%) were 65 years or older. As with any NSAIAs, exercise caution in treating patients 65 years and older.
ICD codes
No ICD codes are available for this drug.
Formulary status
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Last reviewed · Source: First Databank (FDB) drug data
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