Naproxen is a nonselectiveCOX inhibitor.[8] As an NSAID, naproxen appears to exert its anti-inflammatory action by reducing the production of inflammatory mediators calledprostaglandins.[10] It is metabolized by the liver to inactive metabolites.[8]
Naproxen was patented in 1967 and approved for medical use in the United States in 1976.[11][8][12] In the United States it is availableover-the-counter and as ageneric medication.[8][13] In 2022, it was the 88th most commonly prescribed medication in the United States, with more than 7million prescriptions.[14][15]
Naproxen sodium is available as both an immediate-release and an extended-release tablet. The extended-release formulations (sometimes called "sustained release", or "enteric coated") take longer to take effect than the immediate-release formulations and therefore are less useful when immediate pain relief is desired. Extended-release formulations are more useful for the treatment of chronic, or long-lasting, conditions, in which long-term pain relief is desirable.[17]
250mg tablet of naproxen
220mg tablet of naproxen sodium. Imprint L490 (upside-down). Round, light blue tablet[17]
As with all non-steroidal anti-inflammatory medications (NSAIDs), naproxen use should be avoided in pregnancy due to the importance of prostaglandins in vascular and renal function in the fetus. NSAIDs should especially be avoided in the third trimester. Small amounts of naproxen are excreted in breast milk.[1] However, adverse effects are uncommon in infants breastfed from a mother taking naproxen.[18]
Common adverse effects include dizziness, drowsiness, headache, rash, bruising, and gastrointestinal upset.[11][1] Heavy use is associated with an increased risk of end-stage renal disease and kidney failure.[11][19] Naproxen may causemuscle cramps in the legs in 3% of people.[20]
In October 2020, the U.S.Food and Drug Administration (FDA) required thedrug label to be updated for all nonsteroidal anti-inflammatory medications to describe the risk of kidney problems in unborn babies that result in low amniotic fluid.[21][22] They recommend avoiding NSAIDs in pregnant women at 20 weeks or later in pregnancy.[21][22]
As with other non-COX-2 selective NSAIDs, naproxen can causegastrointestinal problems, such as heartburn, constipation, diarrhea, ulcers and stomach bleeding.[23] Naproxen should be taken orally with, or just after food, to decrease the risk ofgastrointestinal side effects.[24] Persons with a history ofulcers orinflammatory bowel disease should consult a doctor before taking naproxen.[24] In U.S. markets, naproxen is sold withboxed warnings about the risk of gastrointestinal ulceration or bleeding.[1] Naproxen poses an intermediate risk of stomach ulcers compared withibuprofen, which is low-risk, andindometacin, which is high-risk.[25] To reduce stomach ulceration risk, it is often combined with aproton-pump inhibitor (a medication that reducesstomach acid production) during long-term treatment of those with pre-existing stomach ulcers or a history of developing stomach ulcers while on NSAIDs.[26][27]
COX-2 selective and nonselectiveNSAIDs have been linked to increases in the number of serious and potentially fatal cardiovascular events, such asmyocardial infarctions andstrokes.[28] Naproxen is, however, associated with the smallest overall cardiovascular risks.[29][30] Cardiovascular risk must be considered when prescribing any nonsteroidal anti-inflammatory drug. The drug had roughly 50% of the associated risk of stroke compared withibuprofen and was also associated with a reduced number of myocardial infarctions compared withcontrol groups.[29]
A study found that high-dose naproxen induced near-complete suppression of plateletthromboxane throughout the dosing interval and appeared not to increasecardiovascular disease (CVD) risk, whereas other non-aspirin high-dose NSAID regimens had only transient effects on plateletCOX-1 and were associated with a small but definite vascular hazard. Conversely, naproxen was associated with higher rates of upper gastrointestinal bleeding complications compared with other NSAIDs.[30]
NSAIDs such as naproxen may interfere with and reduce the efficacy ofSSRI antidepressants,[31] as well as increase the risk of bleeding greater than the individual bleeding risk of either class of agent, when taken together.[32] Naproxen is not contraindicated in the presence of SSRIs, though concomitant use of the medications should be done with caution.[32]Alcohol consumption increases the risk ofgastrointestinal bleeding when combined with NSAIDs like naproxen in adose-dependent manner (that is, the higher the dose of naproxen, the higher the risk of bleeding).[33] The risk is highest for people who are heavy drinkers.[33]
Naproxen is a minor substrate ofCYP1A2 andCYP2C9. It is extensively metabolized in the liver to 6-O-desmethylnaproxen, and both the parent drug and the desmethyl metabolite undergo further metabolism to their respective acylglucuronide conjugated metabolites.[39] An analysis of twoclinical trials shows that naproxen's time topeak plasma concentration occurs between 2 and 4 hours after oral administration, though naproxen sodium reaches peak plasma concentrations within 1–2 hours.[7][clarification needed]
Thepharmacogenetics of naproxen has been studied to better understand its adverse effects.[40] In 1998, a smallpharmacokinetic (PK) study failed to show that differences in a patient's ability toclear naproxen from the body could account for differences in a patient's risk of experiencing the adverse effect of a serious gastrointestinal bleed while taking naproxen.[40] However, the study failed to account for differences in the activity ofCYP2C9, a drug-metabolizing enzyme that is necessary for clearing naproxen.[40] Studies on the relationship between CYP2C9genotype and NSAID-induced gastrointestinal bleeds have shown that genetic variants in CYP2C9 that reduce the clearance of major CYP2C9 substrates (like naproxen) increase the risk of NSAID-induced gastrointestinal bleeds, especially forhomozygous defective variants.[40]
Naproxen is a member of the2-arylpropionic acid (profen) family of NSAIDs.[41] The free acid is an odorless, white to off-white crystalline substance.[citation needed] Naproxen free base islipid-soluble and practically insoluble in water, while naproxen sodium and many other salts are freely soluble in water, often soluble in methanol, and sparingly soluble in alcohol; check the specific solubility of each salt before use. Naproxen has amelting point of 152–155°C, while naproxen salts tend to have higher melting points.[citation needed]
Naproxen and naproxen sodium are marketed under variousbrand names, including Accord, Aleve, Anaprox, Antalgin, Apranax, Feminax Ultra, Flanax, Inza, Maxidol, Nalgesin, Naposin, Naprelan, Naprogesic, Naprosyn, Narocin, Pronaxen, Proxen, Soproxen, and Xenifar.[2] It is also available as the combinationnaproxen/esomeprazole magnesium in delayed-release tablets under the brand name Vimovo.[2][43]
Syntex first marketed naproxen in 1976, as theprescription drug Naprosyn. They first marketed naproxen sodium under the brand name Anaprox in 1980. It remains a prescription-only drug in much of the world.[citation needed] In the United States, theFood and Drug Administration (FDA) approved it as anover-the-counter (OTC) drug in 1994. OTC preparations of naproxen in the U.S. are mainly marketed byBayer HealthCare under the brand name Aleve and genericstore brand formulations in 220mg tablets.[44] In Australia, packets of 275mg tablets of naproxen sodium areSchedule 2 pharmacy medicines, with a maximum daily dose of five tablets or 1375mg. In the United Kingdom, 250mg tablets of naproxen were approved for OTC sale under the brand name Feminax Ultra in 2008, for the treatment of primarydysmenorrhoea in women aged 15 to 50.[45] In the Netherlands, 220mg and 275mg tablets are available OTC in drugstores, 550mg is OTC only at pharmacies. Aleve became available over the counter in some provinces in Canada[46] on 14 July 2009, but notBritish Columbia,Quebec orNewfoundland and Labrador;[47] it subsequently became available OTC in British Columbia in January 2010.[48]
Naproxen has been found in groundwater and drinking water in concentrations high enough to have adverse effects on invertebrates including fungi, algae, bacteria and fishes.[49] Naproxen is not thoroughly removed by conventional water treatment methods,[50] and its degradation pathways in the environment are limited.[51][52] Some methods more successfully remove naproxen from wastewater, includingmetal-organic complexes andporous carbon.[53] Although the levels are generally low enough to not be acutely toxic, sub-lethal effects may still occur,[54] such as reduced photosynthetic ability.[55]
Naproxen may have antiviral activity againstinfluenza. In laboratory research, it blocks the RNA-binding groove of the nucleoprotein of the virus, preventing the formation of the ribonucleoprotein complex—thus taking the viral nucleoproteins out of circulation.[56]
Naproxen is given by mouth to horses at a dose of 10mg/kg and has shown to have a wide safety margin (no toxicity when given at three times the recommended dose for 42 days).[57] It is more effective formyositis than the commonly used NSAIDphenylbutazone, and has shown especially good results for treatment ofequine exertional rhabdomyolysis,[58] a disease of muscle breakdown; it is less commonly used formusculoskeletal disease.[medical citation needed]
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^Mulkiewicz E, Wolecki D, Świacka K, Kumirska J, Stepnowski P, Caban M (October 2021). "Metabolism of non-steroidal anti-inflammatory drugs by non-target wild-living organisms".The Science of the Total Environment.791: 148251.Bibcode:2021ScTEn.79148251M.doi:10.1016/j.scitotenv.2021.148251.PMID34139498.
^Huynh NC, Nguyen TT, Nguyen DT, Tran TV (November 2023). "Occurrence, toxicity, impact and removal of selected non-steroidal anti-inflammatory drugs (NSAIDs): A review".The Science of the Total Environment.898: 165317.Bibcode:2023ScTEn.89865317H.doi:10.1016/j.scitotenv.2023.165317.PMID37419350.
^Parolini M (October 2020). "Toxicity of the Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) acetylsalicylic acid, paracetamol, diclofenac, ibuprofen and naproxen towards freshwater invertebrates: A review".The Science of the Total Environment.740: 140043.Bibcode:2020ScTEn.74040043P.doi:10.1016/j.scitotenv.2020.140043.hdl:2434/747078.PMID32559537.
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