Nabumetone

228.29

228.29

LW0TIW155Z

758623

DTXSID4045472

C47627

M01AX01|M - Musculo-skeletal system

2914509090

26.3

3.1

Solid

1.1±0.1 g/cm3

80 °C

372.3°C at 760 mmHg

165.4±14.5 °C

1.576

Practically insoluble in water;soluble in alcohol or chloroform

Refrigerator

148 Ų [M+H]+ [CCS Type: TW, Method: calibrated with polyalanine and drug standards]

NONH for all modes of transport

2

22-40

36/37

EL9085000

Xn

P201, P202, P260, P261, P264, P270, P271, P273, P280, P281, P301+P312, P302+P352, P304+P312, P304+P340, P305+P351+P338, P308+P313, P312, P314, P321, P330, P332+P313, P337+P313, P362, P391, P403+P233, P405, P501

H302

|Warning|H302 (50%): Harmful if swallowed [Warning Acute toxicity, oral]|P201, P202, P260, P261, P264, P270, P271, P273, P280, P281, P301+P312, P302+P352, P304+P312, P304+P340, P305+P351+P338, P308+P313, P312, P314, P321, P330, P332+P313, P337+P313, P362, P391, P403+P233, P405, and P501|Aggregated GHS information provided by 7 companies from 7 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

**LD50 Values** Mouse: 4290 mg/kg (Oral), 2380 mg/kg (IP) Rat: 3880 mg/kg (Oral), 1520 mg/kg (IP), >10 g/kg (SC) Monkey: 3200 mg/kg (Oral) **Overdose** Signs and symptoms of nabumetone overdose include lethargy, drowsiness, nausea, vomiting, and epigastric pain. These are considered reversible with supportive care. GI bleeding, hypertension, acute kidney injury, respiratory depression, and coma are rare but can occur. No antidote exists for nabumetone overdose although administration of activated charcoal and/or induction of emesis can reduce absorption if the nabumetone dose was taken less than 4 hours prior. 6-MNA is cannot be cleared by dialysis. **Carcinogenicity & Mutagenicity** Nabumetone was not significantly carcinogenic in rats or mice studied over 2 years. Neither the Ames test nor mouse micronucleus test showed nabumetone or it's active metabolite, 6-MNA, to be mutagenic. Chromosomal abberation has been observed in cultured lymphocytes exposed to concentrations of 80 mcg/mL and higher of nabumetone or 6-MNA equivalent to the maximum recommended human dose. **Reproductive Toxicity** No adverse effects on fertility have been observed in male and female rats at doses of 320 mg/kg/day.] No teratogenicity has been observed in pregnant rabbits or rats. Dystocia and delayed parturition have been noted in rats resulting in reduced survival of offspring. This has been attributed to the role of prostaglandins in uterine contraction. NSAIDs can also cause premature closure of the ductus ateriosus. **Lactation** 6-MNA has been detected in the milk of lactating rats. While no data is available in humans, 6-MNA is both highly protein bound and exists in its anionic form in circulation. For these reasons partitioning into breast milk is expected to be limited.

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.

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

**Indicated** for: 1) Symptomatic relief in rheumatoid arthritis. 2) Symptomatic relief in osteoarthritis.|FDA Label

Nabumetone is a long acting nonsteroidal antiinflammatory drug (NSAID) that is available by prescription only and is used in therapy of chronic arthritis. Nabumetone has been linked to rare instances of clinically apparent, idiosyncratic drug induced liver disease.

Nonsteroidal Antiinflammatory Drugs

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.

Anti-inflammatory agents that are non-steroidal in nature. In addition to anti-inflammatory actions, they have analgesic, antipyretic, and platelet-inhibitory actions.They act by blocking the synthesis of prostaglandins by inhibiting cyclooxygenase, which converts arachidonic acid to cyclic endoperoxides, precursors of prostaglandins. Inhibition of prostaglandin synthesis accounts for their analgesic, antipyretic, and platelet-inhibitory actions; other mechanisms may contribute to their anti-inflammatory effects. (See all compounds classified as Anti-Inflammatory Agents, Non-Steroidal.)|A subclass of cyclooxygenase inhibitors with specificity for CYCLOOXYGENASE-2. (See all compounds classified as Cyclooxygenase 2 Inhibitors.)

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.

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.

6-MNA has a mean half-life of 24 hours with a range of 19-36 hours.

Nabumetone's active metabolite, 6-MNA, is an inhibitor of both COX-1 and COX-2 although it exhibits some COX-2 selectivity. Inhibition of COX-1 and COX-2 reduces conversion of arachidonic acid to PGs and thromboxane (TXA₂). This reduction in prostanoid production is the common mechanism that mediates the effects of nambutone. PGE₂ is the primary PG involved in modulation of nociception. It mediates peripheral sensitization through a variety of effects. PGE₂ activates the G_q-coupled EP₁ receptor leading to increased activity of the inositol trisphosphate/phospholipase C pathway. Activation of this pathway releases intracellular stores of calcium which directly reduces action potential threshold and activates protein kinase C (PKC) which contributes to several indirect mechanisms. PGE₂ also activates the EP₄ receptor, coupled to G_s, which activates the adenylyl cyclase/protein kinase A (AC/PKA) signaling pathway. PKA and PKC both contribute to the potentiation of transient receptor potential cation channel subfamily V member 1 (TRPV1) potentiation, which increases sensitivity to heat stimuli. They also activate tetrodotoxin-resistant sodium channels and inhibit inward potassium currents. PKA further contributes to the activation of the P2X3 purine receptor and sensitization of T-type calcium channels. The activation and sensitization of depolarizing ion channels and inhibition of inward potassium currents serve to reduce the intensity of stimulus necessary to generate action potentials in nociceptive sensory afferents. PGE₂ act via EP₃ to increase sensitivity to bradykinin and via EP₂ to further increase heat sensitivity. Central sensitization occurs in the dorsal horn of the spinal cord and is mediated by the EP₂ receptor which couples to G_s. Pre-synaptically, this receptor increases the release of pro-nociceptive neurotransmitters glutamate, CGRP, and substance P. Post-synaptically it increases the activity of AMPA and NMDA receptors and produces inhibition of inhibitory glycinergic neurons. Together these lead to a reduced threshold of activating, allowing low intensity stimuli to generate pain signals. PGI₂ is known to play a role via its G_s-coupled IP receptor although the magnitude of its contribution varies. It has been proposed to be of greater importance in painful inflammatory conditions such as arthritis. By limiting sensitization, both peripheral and central, via these pathways NSAIDs can effectively reduce inflammatory pain. PGI₂ and PGE₂ contribute to acute inflammation via their IP and EP₂ receptors. Similarly to β adrenergic receptors these are G_s-coupled and mediate vasodilation through the AC/PKA pathway. PGE₂ also contributes by increasing leukocyte adhesion to the endothelium and attracts the cells to the site of injury. PGD₂ plays a role in the activation of endothelial cell release of cytokines through its DP₁ receptor. PGI₂ and PGE₂ modulate T-helper cell activation and differentiation through IP, EP₂, and EP₄ receptors which is believed to be an important activity in the pathology of arthritic conditions. By limiting the production of these PGs at the site of injury, NSAIDs can reduce inflammation. PGE₂ can cross the blood-brain barrier and act on excitatory G_q EP₃ receptors on thermoregulatory neurons in the hypothalamus. This activation triggers an increase in heat-generation and a reduction in heat-loss to produce a fever. NSAIDs prevent the generation of PGE₂ thereby reducing the activity of these neurons. The adverse effects of NSAIDs stem from the protective and regulatory roles of prostanoids which have been well-characterized. PGI₂ and PGE₂ regulate blood flow to the kidney by similar mechanisms to the vasodilation they produce in inflammation. Prevention of this regulation by NSAIDs produces vasoconstriction which limits renal function by reducing blood flow and the hydrostatic pressure which drives filtration. PGE₂ also regulates gastric protection via EP₃ receptors which are, in this location, coupled to G_i which inhibits the AC/PKA pathway. This reduces the secretion of protons by H⁺/K⁺ ATPase in parietal cells and increases the secretion of mucus and HCO₃^- by superficial endothelial cells. Disruption of this protective action by NSAIDs lead to ulceration of the gastric mucosa. Lastly, disruption of PGI₂, which opposes platelet aggregation, generation by COX-2 selective agents leads to an imbalance with TXA₂ generated by COX-1, which promotes aggregation of platelets, leading to increased risk of thrombosis. Since nabumetone is somewhat COX-2 selective it is thought to promote this imbalance and increase thrombotic risk.

4-(6-methoxy-2-naphthyl)-2-butanone

Human Drugs -> FDA Approved Drug Products with Therapeutic Equivalence Evaluations (Orange Book) -> Active Ingredients|Pharmaceuticals