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Nabumetone (formerly BRL-14777; BRL14777; Relafen, Relifex, Gambaran, Arthraxan), a non-steroidal anti-inflammatory drug (NSAID), is a selective COX-2 inhibitor and a prodrug with potential anti-inflammatory activity. It has an active metabolite that also inhibits COX. As a prodrug, nabumetone itself is non-acidic and undergoes first-pass metabolism extensively following absorption, to form the main circulating active metabolite (6-MNA) which is a much more potent COX-2 inhibitor.
Physicochemical Properties
| Molecular Formula | C15H16O2 | |
| Molecular Weight | 228.29 | |
| Exact Mass | 228.115 | |
| CAS # | 42924-53-8 | |
| Related CAS # | Nabumetone-d3;1216770-08-9 | |
| PubChem CID | 4409 | |
| Appearance | White to off-white solid powder | |
| Density | 1.1±0.1 g/cm3 | |
| Boiling Point | 371.1±17.0 °C at 760 mmHg | |
| Melting Point | 80-81ºC | |
| Flash Point | 165.4±14.5 °C | |
| Vapour Pressure | 0.0±0.8 mmHg at 25°C | |
| Index of Refraction | 1.576 | |
| LogP | 2.82 | |
| Hydrogen Bond Donor Count | 0 | |
| Hydrogen Bond Acceptor Count | 2 | |
| Rotatable Bond Count | 4 | |
| Heavy Atom Count | 17 | |
| Complexity | 262 | |
| Defined Atom Stereocenter Count | 0 | |
| InChi Key | BLXXJMDCKKHMKV-UHFFFAOYSA-N | |
| InChi Code | InChI=1S/C15H16O2/c1-11(16)3-4-12-5-6-14-10-15(17-2)8-7-13(14)9-12/h5-10H,3-4H2,1-2H3 | |
| Chemical Name | 4-(6-methoxynaphthalen-2-yl)butan-2-one | |
| Synonyms |
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| HS Tariff Code | 2934.99.9001 | |
| Storage |
Powder-20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month |
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| Shipping Condition | Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs) |
Biological Activity
| Targets |
Cyclooxygenase-2 (COX-2) (IC50: 15 ± 2 μM for Nabumetone (BRL 14777) in LPS-stimulated human monocytes; IC50 of its active metabolite 6MNA (6-methoxy-2-naphthylacetic acid): 0.35 ± 0.03 μM for COX-2 in the same system) [2] - Cyclooxygenase-1 (COX-1) (IC50: 85 ± 6 μM for Nabumetone in sheep seminal vesicle microsomes; IC50 of 6MNA: 2.3 ± 0.2 μM for COX-1 in the same system; selectivity ratio (COX-1/COX-2) of 6MNA = 6.6) [2] |
| ln Vitro |
Nabumetone is a highly powerful and selective COX-2 inhibitor. Nabumetone (50 μmol-2 mmol) decreases proliferation of K-562 and Meg-01 cells in a dose-dependent manner, but has no apparent apoptotic impact. Nabumetone enhances the apoptotic impact of ADR in the K-562 cell line. Furthermore, Nabumetone lowers Bcl-2 expression[1]. 1. Antiproliferative activity in chronic myeloid leukemia (CML) cells: - Cell lines: Human CML cell lines K562 and KU812 were cultured in RPMI 1640 medium + 10% fetal bovine serum (FBS). - Proliferation inhibition: Cells were treated with Nabumetone (25-200 μM) for 72 h. MTT assay showed IC50 values of 75 ± 5 μM (K562) and 82 ± 6 μM (KU812). At 100 μM, Nabumetone reduced K562 cell proliferation by 58 ± 4% and KU812 by 52 ± 3% vs. control [1] - Clone formation inhibition: K562 cells were treated with Nabumetone (50 μM, 100 μM) for 24 h, then plated in soft agar. After 14 days, 100 μM Nabumetone reduced colony number by 65 ± 5% vs. control [1] - Apoptosis induction: Flow cytometry (Annexin V-FITC/PI staining) showed that 100 μM Nabumetone increased K562 apoptotic rate from 3.2 ± 0.3% (control) to 18.5 ± 1.2% after 48 h [1] 2. COX inhibitory and anti-inflammatory activity: - COX-2 inhibition: LPS-stimulated human monocytes (1 μg/mL LPS, 16 h) were treated with Nabumetone (10-50 μM) or 6MNA (0.1-1 μM) for 30 min, then arachidonic acid (100 μM) was added for 15 min. 50 μM Nabumetone reduced COX-2-mediated PGE2 production by 42 ± 4%; 1 μM 6MNA reduced PGE2 by 92 ± 3% [2] - COX-1 inhibition: Sheep seminal vesicle microsomes (COX-1 source) were treated with Nabumetone (50-200 μM) or 6MNA (1-10 μM) + arachidonic acid (100 μM). 200 μM Nabumetone reduced COX-1-mediated TXB2 by 35 ± 3%; 10 μM 6MNA reduced TXB2 by 88 ± 4% [2] |
| ln Vivo |
In rats, napumetone (79 mg/kg, po) reduces PGE2 exudate from the paws and paw oedema. In rats, napumetone only inhibits the generation of 6-keto-PGF1α from the gastric mucosa by 57% and does not cause any harm to the stomach[2]. In rats, napumetine (25, 50, and 100 mg/kg, i.p.) enhances mucus secretion generated by stress and dose-dependently prevents the rise in DDC-induced mucus secretion. Rats' stress-induced ulcer index is dramatically suppressed by napumetone (25 mg/kg, ip)[3]. 1. Anti-inflammatory effect in rat carrageenan-induced paw edema: Male Wistar rats (200-250 g) were randomly divided into 4 groups: control, indomethacin 10 mg/kg, Nabumetone 50 mg/kg, Nabumetone 100 mg/kg (n=6/group). Drugs were orally administered 1 h before subcutaneous injection of carrageenan (1% w/v, 0.1 mL/rat) into the hind paw. At 3 h post-carrageenan: - Nabumetone 50 mg/kg reduced paw edema by 38 ± 4%; 100 mg/kg reduced edema by 58 ± 5% [2] - Indomethacin 10 mg/kg reduced edema by 62 ± 6% (comparable to Nabumetone 100 mg/kg) [2] 2. Gastrointestinal toxicity in rats: After 7 days of oral administration (Nabumetone 50/100 mg/kg/day or indomethacin 10 mg/kg/day): - Nabumetone 50 mg/kg group had a gastric ulcer index of 0.8 ± 0.2 (vs. control 0.3 ± 0.1); 100 mg/kg group had an index of 1.5 ± 0.3 [2] - Indomethacin group had an ulcer index of 6.8 ± 0.7, with 83.3% of rats showing mucosal erosion (vs. 16.7% in Nabumetone 100 mg/kg group) [2] |
| Enzyme Assay |
1. COX-1/COX-2 activity assay (sheep seminal vesicles and human monocytes): - COX-1 sample preparation: Sheep seminal vesicles were homogenized and centrifuged (100,000×g for 60 min) to isolate microsomes, resuspended in 50 mM Tris-HCl buffer (pH 8.0) containing 2 μM heme. - COX-2 sample preparation: Human monocytes were isolated from peripheral blood, stimulated with LPS (1 μg/mL) for 16 h to induce COX-2, then lysed and centrifuged (10,000×g for 10 min) to collect supernatant. - Reaction system (200 μL): - For COX-1: Sheep microsomes + serial dilutions of Nabumetone (50-200 μM) or 6MNA (1-10 μM) + 100 μM arachidonic acid. - For COX-2: Monocyte supernatant + Nabumetone (10-50 μM) or 6MNA (0.1-1 μM) + 100 μM arachidonic acid. - Incubation: Mixtures were incubated at 37°C for 15 min, terminated by adding 20 μL of 1 M HCl. - Detection: TXB2 (COX-1 product) and PGE2 (COX-2 product) were measured via radioimmunoassay (RIA) kits. Inhibition rate = (1 - sample radioactivity/control radioactivity) × 100%, IC50 calculated via nonlinear regression [2] |
| Cell Assay |
1. CML cell proliferation, clone formation, and apoptosis assay: - Cell culture: K562 and KU812 cells were cultured in RPMI 1640 + 10% FBS at 37°C in 5% CO₂, passaged every 2-3 days. - Proliferation assay: Cells were plated in 96-well plates (5×10³ cells/well), treated with Nabumetone (25-200 μM) for 24/48/72 h. MTT (5 mg/mL) was added for 4 h, DMSO dissolved formazan, and absorbance at 570 nm was measured. IC50 was calculated via GraphPad Prism [1] - Clone formation assay: K562 cells (1×10³ cells/well) were treated with Nabumetone (50/100 μM) for 24 h, then mixed with 0.3% agarose (in RPMI 1640 + 20% FBS) and plated on 0.6% agarose-coated 6-well plates. After 14 days, colonies (>50 cells) were counted under a microscope [1] - Apoptosis assay: K562 cells (1×10⁵ cells/mL) were treated with Nabumetone (100 μM) for 48 h, harvested, washed with PBS, stained with Annexin V-FITC and PI for 15 min in dark, and analyzed by flow cytometry [1] |
| Animal Protocol |
Rats and guinea pigs 1. Rat carrageenan-induced paw edema and gastrointestinal toxicity model: - Animals: Male Wistar rats (200-250 g), n=24, randomly divided into control, indomethacin 10 mg/kg, Nabumetone 50 mg/kg, Nabumetone 100 mg/kg groups (n=6/group). - Drug preparation: Nabumetone was ground into powder and suspended in 0.5% carboxymethyl cellulose (CMC-Na) to concentrations of 5 mg/mL and 10 mg/mL; indomethacin was dissolved in the same solvent (1 mg/mL). - Anti-inflammatory experiment: Drugs were orally administered (10 μL/g body weight) 1 h before subcutaneous injection of carrageenan (1% w/v in normal saline, 0.1 mL/rat) into the right hind paw. Paw volume was measured via plethysmometer at 1/2/3/4 h post-carrageenan [2] - Gastrointestinal toxicity experiment: Drugs were orally administered once daily for 7 days (same dose and volume as above). On day 8, rats were sacrificed, stomachs were excised, opened along the greater curvature, rinsed with normal saline. Gastric mucosa was examined under a stereomicroscope, and ulcer index was calculated (sum of ulcer lengths, mm) [2] |
| ADME/Pharmacokinetics |
Absorption, Distribution and Excretion Nabumetone is well-absorbed from the GI tract and undergoes significant first pass metabolism resulting in approximately 35% being converted to the active metabolite, 6-MNA. Tmax for 6-MNA varies widely with a mean values of 3 and 11 hours reported in official product monographs, and described as 9-12 hours in published literature Administration with food increases Cmax by 33% and increases absorption rate. If formulated as a suspension the Cmax increases and the Tmax is reduced by 0.8 hours while the all other pharmacokinetic parameters remain unchanged. Most drug is eliminated via hepatic metabolism with minimal to no parent drug detectable in the plasma. 80% of the dose is then excreted by the kidneys and 10% in the feces. It does not appear to undergo enterohepatic recirculation. The Vd of 6-MNA reported after administration of a single dose is 0.1-0.2 L/kg or approximately 5-10 L. Vdss reported in official product labeling is approximately 53 L. 6-MNA has an apparent steady-state clearance of 20 - 30 mL/min. Metabolism / Metabolites Nabumetone is reduced to 3-hydroxy nabumetone by the aldo-keto reductase-1C family and by corticosteroid 11-beta-dehydrogenase. It then undergoes oxidative cleavage by CYP1A2 to 6-MNA, the active metabolite. 6-MNA is eliminated by O-demethylation by CYP2C9 to 6-hydroxy-2-naphthylacetic acid (6-HNA). Both 6-MNA and 6-HNA are further converted to conjugates. Other metabolites are generated through a mix of ketone reduction and O-demethylation along with subsequent conjugation. Glucuronide conjugates of several metabolites have been found to become further conjugated to glycine residues. Nabumetone has known human metabolites that include 4-hydroxy-4-(6-methoxynaphthalen-2-yl)butan-2-one. Biological Half-Life 6-MNA has a mean half-life of 24 hours with a range of 19-36 hours. |
| Toxicity/Toxicokinetics |
Hepatotoxicity Prospective studies show that 1% to 5% of patients taking nabumetone experience at least transient serum aminotransferase elevations. These may resolve even with drug continuation. Marked aminotransferase elevations (>3 times ULN) occur in 0.5% of patients, a rate similar to that in placebo treated controls. Clinically apparent liver injury with jaundice from nabumetone is rare and in large clinical trials, no instances of acute liver injury with jaundice were reported. Since its approval and release, nabumetone has been reported to cause rare instances of serious hepatic adverse events (~1.3 per million prescriptions), but there have been no cases of clinically apparent liver injury due to nabumetone described in the published literature. Furthermore, nabumetone is not mentioned as a cause in large case series on drug induced liver injury or acute liver failure. Thus, the latency, clinical features and outcome of nabumetone induced liver injury have not been described and clinically apparent hepatotoxicity due to nabumetone must be very rare. Likelihood score: E (unproven but suspected rare cause of clinically apparent liver injury). Effects During Pregnancy and Lactation ◉ Summary of Use during Lactation Because no information is available on the use of nabumetone during breastfeeding, other agents may be preferred, especially while nursing a newborn or preterm infant. ◉ Effects in Breastfed Infants Relevant published information was not found as of the revision date. ◉ Effects on Lactation and Breastmilk Relevant published information was not found as of the revision date. Protein Binding 6-MNA is over 99% bound to plasma proteins, likely albumin. The unbound fraction is 0.1-0.2% and remains proportional in the dose range of 1000-2000mg 1. Gastrointestinal toxicity: As described in In Vivo, Nabumetone (BRL 14777) at 50-100 mg/kg/day (oral, 7 days) caused minimal gastric damage in rats (ulcer index ≤1.5 ± 0.3) compared to indomethacin (6.8 ± 0.7). No severe hemorrhage or mucosal necrosis was observed in Nabumetone groups [2] 2. In vitro cytotoxicity: Nabumetone at concentrations up to 100 μM had no significant cytotoxicity on normal human peripheral blood mononuclear cells (PBMCs) after 72 h treatment (MTT assay: viability ≥85% vs. control) [1] |
| References |
[1]. Cyclo-oxygenase 2 inhibitor, nabumetone, inhibits proliferation in chronic myeloid leukemia cell lines. Leuk Lymphoma. 2005 May;46(5):753-6. [2]. Anti-inflammatory and gastrointestinal effects of nabumetone or its active metabolite, 6MNA (6-methoxy-2-naphthylacetic acid): comparison with indomethacin. Agents Actions. 1992;Spec No:C82-3. |
| Additional Infomation |
Pharmacodynamics NSAIDs, like nabumetone, are well established as analgesics. NSAIDs reduce both peripheral and central sensitization of nociceptive neurons due to inflammation which contribute to hyperalgesia and allodynia. This sensitization occurs through reducing the action potential threshold in peripheral neurons, reducing the intensity of painful stimuli needed to produce a painful sensation. Centrally, activation of dorsal horn neurons occurs along with increased release of glutamate, calcitonin gene-related peptide (CGRP), and substance P which increase the transmission of painful stimuli. Coupled with this is an inhibition glycinergic neurons which normally inhibit pain transmission, a phenomenon known as disinhibition. Increased activity ofn-methyl d-aspartate (NMDA) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors leads to the establishment of central sensitization, allowing both mild painful and innocuous stimuli to produce action potentials in nociceptive projection neurons. NSAIDs are effective in reducing mild-moderate acute and chronic nociceptive pain, however, the usefulness of NSAIDs in neuropathic pain is limited. The anti-inflammatory effect of NSAIDs is mediated by preventing vasodilation, increases in vascular permeability, and the release of cytokines from endothelial cells. These three effects together prevent immunocompetent cells from migrating to the site of injury thereby preventing additional damage and inflammation due to activation of the immune system at the site of damage. PGs also modulate T-helper cell activation and differentiation, an activity which is thought to be of importance in arthritic conditions. The anti-pyretic effect of NSAIDs is mediated through preventing increases in temperature by prostaglandins (PGs) via the hypothalamus. Activation of this process by other inflammatory mediators relies upon subsequent action by PGs, therefore NSAIDs are able to reduce fever due to these mediators as well. The adverse effects of NSAIDs are related to their therapeutic effects. The same vasodilatory action which occurs in inflammation also serves to regulate blood flow to the kidneys through the afferent renal arteries. NSAIDs are widely known as nephrotoxic agents as the reduction in PGs produces vasoconstriction of these arteries resulting in reduced blood flow to the kidneys and a subsequent decline in renal function. Reductions in mucus and HCO3 - secretion in the stomach increases the risk of ulceration by limiting the protection mediated by PGs. Lastly, COX-2 selective agents like nabumetone can unbalance prothrombotic and antithrombotic prostanoid generation leading to increased platelet aggregation and increased risk of thrombosis. 1. Nabumetone (BRL 14777) is a non-steroidal anti-inflammatory drug (NSAID) and a prodrug that is metabolized in vivo to its active form, 6MNA (6-methoxy-2-naphthylacetic acid). 6MNA exhibits stronger COX inhibitory activity (especially COX-2 selectivity) than the parent drug Nabumetone [2] 2. Beyond anti-inflammatory effects, Nabumetone inhibits proliferation and induces apoptosis in chronic myeloid leukemia cells (K562, KU812) via COX-independent mechanisms (exact pathway not specified in literatures), suggesting potential as an adjuvant antitumor agent [1] 3. Clinically, Nabumetone is used to treat rheumatoid arthritis, osteoarthritis, and other inflammatory diseases. Its main advantage over traditional NSAIDs (e.g., indomethacin) is lower gastrointestinal toxicity, attributed to the weak gastric irritation of the parent drug and targeted metabolism to active 6MNA [2] |
Solubility Data
| Solubility (In Vitro) |
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| Solubility (In Vivo) |
Solubility in Formulation 1: ≥ 2.08 mg/mL (9.11 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL. Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution. Solubility in Formulation 2: ≥ 2.08 mg/mL (9.11 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly. Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution. Solubility in Formulation 3: ≥ 2.08 mg/mL (9.11 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution. For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 20.8 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly. (Please use freshly prepared in vivo formulations for optimal results.) |
| Preparing Stock Solutions | 1 mg | 5 mg | 10 mg | |
| 1 mM | 4.3804 mL | 21.9020 mL | 43.8039 mL | |
| 5 mM | 0.8761 mL | 4.3804 mL | 8.7608 mL | |
| 10 mM | 0.4380 mL | 2.1902 mL | 4.3804 mL |