Non-steroidal Anti-inflammataory Drugs (NSAIDs) DefinitionNonsteroidal anti-inflammatory drugs NSAIDs are a drug class that nonsteroidal anti-inflammatory drugs definition paindecrease nlnsteroidalprevent blood tren e dosage and, in higher doses, decrease inflammation. Side effects depend on the specific drug, but largely include an increased risk of gastrointestinal ulcers and bleedsheart attack and kidney disease. The term nonsteroidal distinguishes these drugs from steroidswhich while having a similar eicosanoid -depressing, anti-inflammatory action, have a broad range of other effects. First used inthe term served to distance these medications from steroids. In cells, these enzymes are involved in the synthesis of key biological mediators, namely prostaglandins which nonsteroidal anti-inflammatory drugs definition involved in inflammationand thromboxanes which are involved in blood clotting.
Definition of NSAID
Nonsteroidal anti-inflammatory drugs NSAIDs are a drug class that reduce pain , decrease fever , prevent blood clots and, in higher doses, decrease inflammation.
Side effects depend on the specific drug, but largely include an increased risk of gastrointestinal ulcers and bleeds , heart attack and kidney disease.
The term nonsteroidal distinguishes these drugs from steroids , which while having a similar eicosanoid -depressing, anti-inflammatory action, have a broad range of other effects. First used in , the term served to distance these medications from steroids. In cells, these enzymes are involved in the synthesis of key biological mediators, namely prostaglandins which are involved in inflammation , and thromboxanes which are involved in blood clotting.
As a result, COX-2 selective inhibitors are generally contraindicated due to the high risk of undiagnosed vascular disease. The most prominent NSAIDs are aspirin , ibuprofen and naproxen , all available over the counter in most countries. It treats pain mainly by blocking COX-2 mostly in the central nervous system, but not much in the rest of the body. NSAIDs are usually used for the treatment of acute or chronic conditions where pain and inflammation are present.
NSAIDs are generally used for the symptomatic relief of the following conditions: This is useful for the management of arterial thrombosis and prevention of adverse cardiovascular events like heart attacks. Aspirin inhibits platelet aggregation by inhibiting the action of thromboxane A 2. In a more specific application, the reduction in prostaglandins is used to close a patent ductus arteriosus in neonates if it has not done so physiologically after 24 hours.
NSAIDs are useful in the management of post-operative dental pain following invasive dental procedures such as dental extraction. When not contra-indicated they are favoured over the use of paracetamol alone due to the anti-inflammatory effect they provide. NSAIDs may be used with caution by people with the following conditions: NSAIDs should usually be avoided by people with the following conditions: The widespread use of NSAIDs has meant that the adverse effects of these drugs have become increasingly common.
In the s high doses of prescription NSAIDs were associated with serious upper gastrointestinal adverse events, including bleeding. NSAIDs, like all drugs, may interact with other medications.
For example, concurrent use of NSAIDs and quinolones may increase the risk of quinolones' adverse central nervous system effects, including seizure. There is an argument over the benefits and risks of NSAIDs for treating chronic musculoskeletal pain. Each drug has a benefit-risk profile  and balancing the risk of no treatment with the competing potential risks of various therapies is the clinician's responsibility.
Rofecoxib Vioxx was shown to produce significantly fewer gastrointestinal adverse drug reactions ADRs compared with naproxen. A statistically significant increase in the incidence of myocardial infarctions was observed in patients on rofecoxib. NSAIDs, aside from aspirin, increase the risk of myocardial infarction and stroke.
NSAIDs aside from low-dose aspirin are associated with a doubled risk of heart failure in people without a history of cardiac disease. A publication  in The Journal of Urology received widespread publicity. A link between NSAID use and erectile dysfunction still existed after controlling for several conditions.
However, the study was observational and not controlled, with low original participation rate, potential participation bias, and other uncontrolled factors. The authors warned against drawing any conclusion regarding cause. Inhibition of prostaglandin synthesis in the GI tract causes increased gastric acid secretion, diminished bicarbonate secretion, diminished mucus secretion and diminished trophic [ clarification needed ] effects on the epithelial mucosa.
Common gastrointestinal ADRs include: Ulceration risk increases with therapy duration, and with higher doses. To minimize GI ADRs, it is prudent to use the lowest effective dose for the shortest period of time—a practice that studies show is often not followed. There are also some differences in the propensity of individual agents to cause gastrointestinal ADRs. Indomethacin , ketoprofen and piroxicam appear to have the highest prevalence of gastric ADRs, while ibuprofen lower doses and diclofenac appear to have lower rates.
Certain NSAIDs, such as aspirin, have been marketed in enteric-coated formulations that manufacturers claim reduce the incidence of gastrointestinal ADRs. Similarly, some believe that rectal formulations may reduce gastrointestinal ADRs. However, consistent with the systemic mechanism of such ADRs, and in clinical practice, these formulations have not demonstrated a reduced risk of GI ulceration.
Commonly, gastric but not necessarily intestinal adverse effects can be reduced through suppressing acid production, by concomitant use of a proton pump inhibitor , e. Misoprostol is itself associated with a high incidence of gastrointestinal ADRs diarrhea. While these techniques may be effective, they are expensive for maintenance therapy. NSAIDs should be used with caution in individuals with inflammatory bowel disease e.
NSAIDs are also associated with a fairly high incidence of adverse drug reactions ADRs on the kidney and over time can lead to chronic kidney disease. The mechanism of these kidney ADRs is due to changes in kidney blood flow. Prostaglandins normally dilate the afferent arterioles of the glomeruli. This helps maintain normal glomerular perfusion and glomerular filtration rate GFR , an indicator of kidney function. This is particularly important in kidney failure where the kidney is trying to maintain renal perfusion pressure by elevated angiotensin II levels.
At these elevated levels, angiotensin II also constricts the afferent arteriole into the glomerulus in addition to the efferent arteriole it normally constricts. Common ADRs associated with altered kidney function include: These agents may also cause kidney impairment, especially in combination with other nephrotoxic agents.
Kidney failure is especially a risk if the patient is also concomitantly taking an ACE inhibitor which removes angiotensin II's vasoconstriction of the efferent arteriole and a diuretic which drops plasma volume, and thereby RPF —the so-called "triple whammy" effect.
NSAIDs in combination with excessive use of phenacetin or paracetamol acetaminophen may lead to analgesic nephropathy. The mechanism of photosensitivity, responsible for the high photoactivity of the 2-arylpropionic acids, is the ready decarboxylation of the carboxylic acid moiety. The specific absorbance characteristics of the different chromophoric 2-aryl substituents, affects the decarboxylation mechanism.
While ibuprofen has weak absorption, it has been reported as a weak photosensitising agent. NSAIDs are not recommended during pregnancy, particularly during the third trimester. Additionally, they are linked with premature birth  and miscarriage.
In contrast, paracetamol acetaminophen is regarded as being safe and well-tolerated during pregnancy, but Leffers et al. In France, the country's health agency contraindicates the use of NSAIDs, including aspirin, after the sixth month of pregnancy. These hypersensitivity reactions differ from the other adverse reactions listed here which are toxicity reactions, i. Other NSAID hypersensitivity reactions are allergy-like symptoms but do not involve true allergic mechanisms; rather, they appear due to the ability of NSAIDs to alter the metabolism of arachidonic acid in favor of forming metabolites that promote allergic symptoms.
Afflicted individuals may be abnormally sensitive to these provocative metabolites or overproduce them and typically are susceptible to a wide range of structurally dissimilar NSAIDs, particularly those that inhibit COX1. The use of NSAIDS for analgesia following gastrointestinal surgery remains controversial, given mixed evidence of an increased risk of leakage from any bowel anastomosis created.
Common adverse drug reactions ADR , other than listed above, include: However, the COX enzymes are expressed constitutively in some areas of the CNS, meaning that even limited penetration may cause adverse effects such as somnolence and dizziness. In very rare cases, ibuprofen can cause aseptic meningitis.
NSAIDs reduce kidney blood flow and thereby decrease the efficacy of diuretics , and inhibit the elimination of lithium and methotrexate. NSAIDs cause decreased ability to form a blood clot , which can increase the risk of bleeding when combined with other drugs that also decrease blood clotting, such as warfarin. NSAIDs may aggravate hypertension high blood pressure and thereby antagonize the effect of antihypertensives ,  such as ACE inhibitors.
Various widely used nonsteroidal anti-inflammatory drugs NSAIDs enhance endocannabinoid signaling by blocking the anandamide-degrading membrane enzyme fatty acid amide hydrolase FAAH. This inhibition is competitively reversible albeit at varying degrees of reversibility , as opposed to the mechanism of aspirin , which is irreversible inhibition.
Prostaglandins act among other things as messenger molecules in the process of inflammation. This mechanism of action was elucidated by John Vane — , who received a Nobel Prize for his work see Mechanism of action of aspirin.
COX-1 is a constitutively expressed enzyme with a "house-keeping" role in regulating many normal physiological processes. One of these is in the stomach lining, where prostaglandins serve a protective role, preventing the stomach mucosa from being eroded by its own acid. NSAIDs have been studied in various assays to understand how they affect each of these enzymes.
While the assays reveal differences, unfortunately, different assays provide differing ratios. Paracetamol acetaminophen is not considered an NSAID because it has little anti-inflammatory activity.
The COX-3 pathway was believed to fill some of this gap but recent findings make it appear unlikely that it plays any significant role in humans and alternative explanation models are proposed. NSAIDs are also used in the acute pain caused by gout because they inhibit urate crystal phagocytosis besides inhibition of prostaglandin synthase.
NSAIDs can be classified based on their chemical structure or mechanism of action. Older NSAIDs were known long before their mechanism of action was elucidated and were for this reason classified by chemical structure or origin. Newer substances are more often classified by mechanism of action. However, the majority are prepared in a racemic mixture. Typically, only a single enantiomer is pharmacologically active.
For some drugs typically profens , an isomerase enzyme in vivo converts the inactive enantiomer into the active form, although its activity varies widely in individuals. This phenomenon is likely responsible for the poor correlation between NSAID efficacy and plasma concentration observed in older studies, when specific analysis of the active enantiomer was not performed. Ibuprofen and ketoprofen are now available in single, active enantiomer preparations dexibuprofen and dexketoprofen , which purport to offer quicker onset and an improved side-effect profile.
Naproxen has always been marketed as the single active enantiomer. NSAIDs within a group tend to have similar characteristics and tolerability. Regarding adverse effects, selective COX-2 inhibitors have lower risk of gastrointestinal bleeding, and there is no significant increase in risk of myocardial infarction.
A consumer report noted that ibuprofen , naproxen, and salsalate are less expensive than other NSAIDs, and essentially as effective and safe when used appropriately to treat osteoarthritis and pain. Most nonsteroidal anti-inflammatory drugs are weak acids, with a pKa of 3—5. They are absorbed well from the stomach and intestinal mucosa. Most NSAIDs are metabolized in the liver by oxidation and conjugation to inactive metabolites that typically are excreted in the urine , though some drugs are partially excreted in bile.
Metabolism may be abnormal in certain disease states, and accumulation may occur even with normal dosage. Ibuprofen and diclofenac have short half-lives 2—3 hours.