An analgesic (colloquially known as a painkiller) is any member of the diverse group of drugs used to relieve pain (achieve analgesia). This derives from Greek an-, "without", and -algia, "pain". Analgesic drugs act in various ways on the peripheral and central nervous systems; they include paracetamol (acetaminophen), the nonsteroidal anti-inflammatory drugs (NSAIDs) such as the salicylates, narcotic drugs such as morphine, synthetic drugs with narcotic properties such as tramadol, and various others. Some other classes of drugs not normally considered analgesics are used to treat neuropathic pain syndromes; these include tricyclic antidepressants and anticonvulsants. This article does not cite any references or sources. ... “Hurting” redirects here. ... The peripheral nervous system or PNS, is part of the nervous system, and consists of the nerves and neurons that reside or extend outside the central nervous system (the brain and spinal cord) to serve the limbs and organs, for example. ... A diagram showing the CNS: 1. ... Paracetamol (INN) (IPA: ) or acetaminophen (USAN), is the active metabolite of phenacetin, a so called coal tar analgesic. ... Non-steroidal anti-inflammatory drugs, usually abbreviated to NSAIDs, are drugs with analgesic, antipyretic and anti-inflammatory effects - they reduce pain, fever and inflammation. ... Salicylic acid is a colorless, crystalline organic carboxylic acid. ... This article does not cite any references or sources. ... Morphine (INN) (IPA: ) is a highly potent opiate analgesic drug and is the principal active agent in opium and the prototypical opiate. ... Tramadol (INN) (IPA: ) is an atypical opioid which is a centrally acting analgesic, used for treating moderate to severe pain. ... Neuropathy is usually short for peripheral neuropathy, meaning a disease of the peripheral nervous system. ... Chemical structure of the tricyclic antidepressant amitriptyline Tricyclic antidepressants are a class of antidepressant drugs first used in the 1950s. ... The anticonvulsants, sometimes also called antiepileptics, belong to a diverse group of pharmaceuticals used in prevention of the occurrence of epileptic seizures. ...

The major classes

Paracetamol and NSAIDs

The exact mechanism of action of paracetamol/acetaminophen is uncertain, but it appears to be acting centrally. Aspirin and the other NSAIDs inhibit cyclooxygenase, leading to a decrease in prostaglandin production; this reduces pain and also inflammation (in contrast to paracetamol and the opioids).^{[citation needed]} Aspirin, or acetylsalicylic acid (IPA: ), (acetosal) is a drug in the family of salicylates, often used as an analgesic (to relieve minor aches and pains), antipyretic (to reduce fever), and as an anti-inflammatory. ... Wikipedia does not yet have an article with this exact name. ... Cyclooxygenase (COX) is an enzyme (EC 1. ... Chemical structure of prostaglandin E1 (PGE1). ... An abscess on the skin, showing the redness and swelling characteristic of inflammation. ...

Paracetamol has few side effects, but dosing is limited by possible hepatotoxicity (potential for liver damage). NSAIDs may predispose to peptic ulcers, renal failure, allergic reactions, and hearing loss.^{[citation needed]} They may also increase the risk of hemorrhage by affecting platelet function. The use of certain NSAIDs in children under 16 suffering from viral illness may contribute to Reye's syndrome. Hepatotoxicity (from hepatic toxicity) is chemical-driven liver damage. ... The liver is an organ present in vertebrates and some other animals. ... A benign gastric ulcer (from the antrum) of a gastrectomy specimen. ... Renal failure is the condition in which the kidneys fail to function properly. ... An allergy is an abnormal, acquired sensitivity to a given substance, including pollen, drugs, or numerous environmental triggers. ... Hearing impairment or deafness is decreased or absent ability to perceive auditory information. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... A 250 ml bag of newly collected platelets. ... Reyes syndrome is a potentially fatal disease that causes numerous detrimental effects to many organs, especially the brain and liver. ...

COX-2 inhibitors

Main article: COX-2 inhibitor

These drugs have been derived from NSAIDs. The cyclooxygenase enzyme inhibited by NSAIDs was discovered to have at least 2 different versions: COX1 and COX2. Research suggested that most of the adverse effects of NSAIDs were mediated by blocking the COX1 (constitutive) enzyme, with the analgesic effects being mediated by the COX2 (inducible) enzyme. The COX2 inhibitors were thus developed to inhibit only the COX2 enzyme (traditional NSAIDs block both versions in general). These drugs (such as rofecoxib and celecoxib) are equally effective analgesics when compared with NSAIDs, but cause less gastrointestinal hemorrhage in particular. However post-launch data indicated increased risk of cardiac and cerebrovascular events with these drugs, and rofecoxib was subsequently withdrawn from the market. The role for this class of drug is currently hotly debated. COX-2 selective inhibitor is a form of Non-steroidal anti-inflammatory drug (NSAID) that directly targets COX-2, an enzyme responsible for inflammation and pain. ... Cyclooxygenase (COX) is an enzyme (EC 1. ... Rofecoxib (IPA: ) is a nonsteroidal anti-inflammatory drug (NSAID) developed by Merck & Co. ... Celecoxib (INN) (IPA: ) is a non-steroidal anti-inflammatory drug (NSAID) used in the treatment of osteoarthritis, rheumatoid arthritis, acute pain, painful menstruation and menstrual symptoms, and to reduce numbers of colon and rectum polyps in patients with familial adenomatous polyposis. ... 2006 is a common year starting on Sunday of the Gregorian calendar. ...

Opiates and morphinomimetics

Morphine, the archetypal opioid, and various other substances (e.g. codeine, oxycodone, hydrocodone, diamorphine, pethidine) all exert a similar influence on the cerebral opioid receptor system. Tramadol and buprenorphine are thought to be partial agonists of the opioid receptors. Dosing of all opioids may be limited by opioid toxicity (confusion, respiratory depression, myoclonic jerks and pinpoint pupils), but there is no dose ceiling in patients who tolerate this. Morphine (INN) (IPA: ) is a highly potent opiate analgesic drug and is the principal active agent in opium and the prototypical opiate. ... Codeine (INN) or methylmorphine is an opiate used for its analgesic, antitussive and antidiarrheal properties. ... Not to be confused with oxytocin. ... Hydrocodone or dihydrocodeinone (marketed as Vicodin, Anexsia, Dicodid, Hycodan (or generically Hydromet), Hycomine, Lorcet, Lortab, Norco, Novahistex, Hydroco, Tussionex, Vicoprofen, Xodol) is a semi-synthetic opioid derived from two of the naturally occurring opiates, codeine and thebaine. ... For other uses, see Heroin (disambiguation). ... Pethidine (INN) or meperidine (USAN) (also referred to as: isonipecaine; lidol; pethanol; piridosal; Algil®; Alodan®; Centralgin®; Demerol®; Dispadol®; Dolantin®; Dolargan® (in Poland);[1] Dolestine®; Dolosal®; Dolsin®; Mefedina®) is a fast-acting opioid analgesic drug. ... To meet Wikipedias quality standards, this article may require cleanup. ... Tramadol (INN) (IPA: ) is an atypical opioid which is a centrally acting analgesic, used for treating moderate to severe pain. ... Buprenorphine, is an opioid drug with partial agonist and antagonist actions. ... Agonists An agonist is a substance that binds to a receptor and triggers a response by the cell. ... Myoclonus is brief, involuntary twitching of a muscle or a group of muscles. ...

Opioids, while very effective analgesics, may have some unpleasant side-effects. Up to 1 in 3 patients starting morphine may experience nausea and vomiting (generally relieved by a short course of antiemetics). Pruritus (itching) may require switching to a different opioid. Constipation occurs in almost all patients on opioids, and laxatives (lactulose, macrogol-containing or co-danthramer) are typically co-prescribed. For other uses, see Nausea (disambiguation). ... Vomiting (also throwing up or emesis) is the forceful expulsion of the contents of ones stomach through the mouth and sometimes the nose. ... An antiemetic is a drug that is effective against vomiting and nausea. ... An itch (Latin: pruritus) is a sensation felt on an area of skin that makes a person or animal want to scratch it. ... Constipation or irregularity, is a condition of the digestive system where a person (or animal) experiences hard feces that are difficult to egest; it may be extremely painful, and in severe cases (fecal impaction) lead to symptoms of bowel obstruction. ... Laxatives are foods, compounds, or drugs taken to induce bowel movements, most often taken to treat constipation. ... Lactulose is a synthetic sugar used in the treatment of constipation and hepatic encephalopathy, a complication of liver disease. ...

When used appropriately, opioids and similar narcotic analgesics are safe and effective, carrying relatively little risk of addiction. Occasionally, gradual tapering of the dose is required to avoid withdrawal symptoms. This article does not cite any references or sources. ... For other uses, see addicted. ...

Specific agents

In patients with chronic or neuropathic pain, various other substances may have analgesic properties. Tricyclic antidepressants, especially amitriptyline, have been shown to improve pain in what appears to be a central manner. The exact mechanism of carbamazepine, gabapentin and pregabalin is similarly unclear, but these anticonvulsants are used to treat neuropathic pain with modest success. Chemical structure of the tricyclic antidepressant amitriptyline. ... Amitriptyline (or Amitryptyline) hydrochloride (sold as Elavil, Tryptanol, Endep, Elatrol, Tryptizol, Trepiline, Laroxyl) is a tricyclic antidepressant drug. ... Carbamazepine (CBZ) is an anticonvulsant and mood stabilizing drug, used primarily in the treatment of epilepsy and bipolar disorder. ... Gabapentin (brand name: Neurontin®) was initially synthesized to mimic the structure of GABA for the treatment of epilepsy. ... Pregabalin (brand name: Lyrica®) is a new anticonvulsant drug indicated as an add on therapy for partial onset seizures and for certain types of neuropathic pain. ... The anticonvulsants, sometimes also called antiepileptics, belong to a diverse group of pharmaceuticals used in prevention of the occurrence of epileptic seizures. ...

Specific forms and uses

Combinations

Analgesics are frequently used in combination, such as the paracetamol and codeine preparations found in many non-prescription pain relievers. They can also be found in combination with vasoconstrictor drugs such as pseudoephedrine for sinus-related preparations, or with antihistamine drugs for allergy sufferers. Codeine (INN) or methylmorphine is an opiate used for its analgesic, antitussive and antidiarrheal properties. ... Pseudoephedrine (commonly abbreviated as PSE) is a sympathomimetic amine commonly used as a decongestant. ... This article does not cite any references or sources. ... An antihistamine is a drug which serves to reduce or eliminate effects mediated by histamine, an endogenous chemical mediator released during allergic reactions, through action at the histamine receptor. ...

The use of paracetamol, as well as aspirin, ibuprofen, naproxen, and other NSAIDS concurrently with weak to mid-range opiates (up to about the hydrocodone level) has been shown to have beneficial synergistic effects by combating pain at multiple sites of action—NSAIDs reduce inflammation which, in some cases, is the cause of the pain itself while opiates dull the perception of pain—thus, in cases of mild to moderate pain caused in part by inflammation, it is generally recommended that the two are prescribed together.[1] Wikipedia does not yet have an article with this exact name. ...

Topical or systemic

Topical analgesia is generally recommended to avoid systemic side-effects. Painful joints, for example, may be treated with an ibuprofen- or diclofenac-containing gel; capsaicin also is used topically. Lidocaine and steroids may be injected into painful joints for longer-term pain relief. Lidocaine is also used for painful mouth sores and to numb areas for dental work and minor medical procedures. Ibuprofen (INN) (IPA: ) (from the earlier nomenclature iso-butyl-propanoic-phenolic acid) is a non-steroidal anti-inflammatory drug (NSAID) originally marketed as Nurofen and since under various trademarks including Act-3, Advil, Brufen, Dorival, Herron Blue, Panafen, Motrin, Nuprin and Ipren or Ibumetin (Sweden), Ibuprom (Poland), IbuHEXAL, Moment (Italy... Diclofenac (marketed as Voltaren®, Voltarol®, Diclon®, Dicloflex® Difen and Cataflam®) is a non-steroidal anti-inflammatory drug (NSAID) taken to reduce inflammation and an analgesic reducing pain in conditions such as in arthritis or acute injury. ... Capsaicin (8-methyl-N-vanillyl-6-nonenamide) is the active component of chili peppers, which are plants belonging to the genus Capsicum. ... Lidocaine (INN) (IPA: ) or lignocaine (former BAN) (IPA: ) is a common local anesthetic and antiarrhythmic drug. ... Glucocorticoids are a class of steroid hormones characterised by an ability to bind with the cortisol receptor and trigger similar effects. ... Lidocaine (INN) (IPA: ) or lignocaine (former BAN) (IPA: ) is a common local anesthetic and antiarrhythmic drug. ... A mouth ulcer or canker sore is a painful open sore inside the mouth caused by a break in the mucous membrane. ... A Dentist and Dental Assistant perform surgery on a patient. ...

Psychotropic agents

Tetrahydrocannabinol (THC) and some other cannabinoids, either from the Cannabis sativa plant or synthetic, have analgesic properties, although the use of cannabis derivatives is illegal in many countries. Other psychotropic analgesic agents include ketamine (an NMDA receptor antagonist), clonidine and other α₂-adrenoreceptor agonists, and mexiletine and other local anaesthetic analogues. Tetrahydrocannabinol, also known as THC, Δ9-THC, Δ9-tetrahydrocannabinol (delta-9-tetrahydrocannabinol), Δ1-tetrahydrocannabinol (using an older numbering scheme), or dronabinol, is the main psychoactive substance found in the Cannabis plant; and additionally so in a variety of other plants. ... Cannabinoids are a group of chemicals which activate the bodys cannabinoid receptors. ... Binomial name Linnaeus Subspecies L. subsp. ... Ketamine is a dissociative anesthetic for use in human and veterinary medicine. ... Clonidine is a direct-acting adrenergic agonist prescribed historically as an anti-hypertensive agent. ... Mexiletine (INN, sold under the trade name Mexitil®) belongs to the Class IB anti-arrhythmic group of medicines. ...

Atypical and/or adjuvant analgesics

Orphenadrine, cyclobenzaprine, scopolamine, atropine, gabapentin, first-generation antidepressants and other drugs possessing anticholinergic and/or antispasmodic properties are used in many cases along with analgesics to potentiate centrally acting analgesics such as opioids when used against pain especially of neuropathic origin and to modulate the effects of many other types of analgesics by action in the parasympathetic nervous system. Dextromethorphan has been noted to slow the development of tolerance to opioids and exert additional analgesia by acting upon the NMDA receptors; some analgesics such as methadone and ketobemidone and perhaps piritramide have intrinsic NMDA action. Orphenadrine (Norflex®, Disipal®, Banflex®, Flexon® and others) is an anticholinergic and NMDA receptor antagonist [1]drug belonging to the ethanolamine class of antihistamines. ... Cyclobenzaprine is a skeletal muscle relaxant and a central nervous system (CNS) depressant. ... Scopolamine, also known as hyoscine, is a tropane alkaloid drug obtained from plants of the family Solanaceae (nightshades), such as henbane or jimson weed (Datura species). ... Atropine is a tropane alkaloid extracted from the deadly nightshade (Atropa belladonna) and other plants of the family Solanaceae. ... Gabapentin (brand name: Neurontin®) was initially synthesized to mimic the structure of GABA for the treatment of epilepsy. ... An antidepressant is a medication used primarily in the treatment of clinical depression. ... An anticholinergic agent is a member of a class of pharmaceutical compounds which serve to reduce the effects mediated by acetylcholine in the central nervous system and peripheral nervous system. ... An antispasmodic is a drug that suppresses smooth muscle contraction, especially in tubular organs. ... An opioid is any agent that binds to opioid receptors found principally in the central nervous system and gastrointestinal tract. ... Autonomic nervous system innervation, showing the sympathetic and parasympathetic (craniosacral) systems, in red and blue, respectively The parasympathetic nervous system is one of three divisions of the autonomic nervous system. ... Dextromethorphan (DXM or DM) is an antitussive (cough-suppressant) drug found in many over-the-counter cold and cough medicines. ... NMDA (N-methyl-D-aspartic acid) is an amino acid derivative acting as a specific agonist at the NMDA receptor, and therefore mimics the action of the neurotransmitter glutamate on that receptor. ... Methadone is a synthetic opioid, used medically as an analgesic and in the treatment of narcotic addiction. ... Ketobemidone structure Ketobemidone is a powerful opioid analgesic. ... Piritramide (Dipidolor®) is a synthetic opioid analgesic with about 65-75 percent of the mg-for-mg strength of morphine. ...

The use of adjuvant analgesics is an important and growing part of the pain-control field and new discoveries are made practically every year. Many of these drugs combat the side effects of opioid analgesics, an added bonus. For example, antihistamines including orphenadrine combat the release of histamine caused by many opioids, methylphenidate, caffeine, ephedrine, dextroamphetamine, and cocaine work against heavy sedation and may elevate mood in distressed patients as do the antidepressants. The one indisputably true benefit of THC to chronic pain patients on opioids may be its superior anti-nauseant action. However, it would make more sense to use the Marinol capsule, or oral, rectal, or vapour administration of hash oil, rather than smoking cannabis, for the same reasons most doctors advise against smoking tobacco. In medicine, adjuvants are agents which modify the effect of other agents while having few if any direct effects when given by themselves. ... An antihistamine is a drug which serves to reduce or eliminate effects mediated by histamine, an endogenous chemical mediator released during allergic reactions, through action at the histamine receptor. ... Vitamin R redirects here. ... Caffeine is a xanthine alkaloid compound that acts as a stimulant in humans. ... Ephedrine (EPH) is a sympathomimetic amine similar in structure to the synthetic derivatives amphetamine and methamphetamine. ... Dextroamphetamine is a powerful psychostimulant which produces increased wakefulness, energy and self-confidence in association with decreased fatigue and appetite. ... Cocaine is a crystalline tropane alkaloid that is obtained from the leaves of the coca plant. ...

Addiction

In the United States in recent years, there has been a wave of new addictions to prescription narcotics such as oxycodone (Percocet) and hydrocodone (Vicodin, Lortab etc.) when available in pure formulations as opposed to combined with other medications (as in Percocet which contains both oxycodone and acetaminophen/paracetamol). Hydrocodone is only available in pure form in some European countries as the original hydrocodone pharmaceutical, Dicodid tablets. Far from reducing addiction liability, the paracetamol content of many codeine, dihydrocodeine, hydrocodone, and oxycodone pharmaceuticals in the United States only saddles users with the high risk of severe liver damage, and extraction of the opioids with cold water or solvents reduces this problem for the sophisticated abuser, self-medicator, and legitimate prescription holder alike [2]. Most hydrocodone, codeine, and dihydrocodeine cough syrups available in the United States also contain active ingredients such as acetaminophen which are dangerous in overdose. For other uses, see addicted. ... Not to be confused with oxytocin. ... Hydrocodone or dihydrocodeinone (marketed as Vicodin, Anexsia, Dicodid, Hycodan (or generically Hydromet), Hycomine, Lorcet, Lortab, Norco, Novahistex, Hydroco, Tussionex, Vicoprofen, Xodol) is a semi-synthetic opioid derived from two of the naturally occurring opiates, codeine and thebaine. ... It has been suggested that this article or section be merged into Hydrocodone. ... Oxycodone is a very powerful and potentially addictive opioid analgesic medication synthesized from thebaine. ... Paracetamol (INN) (IPA: ) or acetaminophen (USAN), is the active metabolite of phenacetin, a so called coal tar analgesic. ...

See also

• Pain management
• Patient-controlled analgesia
• Co-proxamol

Pain management (also called pain medicine) is the discipline concerned with the relief of pain. ... Patient-controlled analgesia (PCA) is any method of allowing a person in pain to adminster their own pain relief. ... Dextropropoxyphene is an analgesic in the opioid category. ...

References

• Cancer pain relief and palliative care. Report of a WHO expert committee [World Health Organization Technical Report Series, 804] . Geneva, Switzerland: World Health Organization; 1990. pp. 1–75. ISBN 92-4-120804-X.
• Bandolier pain site (Oxford pain group)

External links

• FDA proposes new pain reliever warnings