Analgesics are drugs that relieve pain. They are divided into two main groups: opioid analgesics and nonopioid analgesics. Opioid analgesics act on opioid receptors in the brain and include natural alkaloids like morphine and codeine, semi-synthetic opiates, and synthetic opioids. They are effective for both short-term and long-term severe pain relief but can cause side effects like addiction, respiratory depression, and constipation. Nonopioid analgesics like NSAIDs alleviate pain by reducing inflammation and are used for mild to moderate pain relief with fewer side effects than opioids.
8. NONOPIOIDANALGESICS
NSAIDS (non-steroidal anti-inflammatory drugs) /
nonnarcotics/aspirinlikeanalgesics
Nonopioidanalgesicswhichalleviatepainbyreducinglocal
inflammatory responses. In contrast, the anti-inflammatory
compounds are used for short-term pain
reliefandformodestpain,suchasthatofheadache,musclestrain,
bruising,orarthritis.
14. Non opioid analgesics ( anti-
inflammatoryanalgesics)
Mostanti-
inflammatoryanalgesicsarederivedfromthreecompoundsd
iscoveredinthe19thcentury
salicylicacid,
pyrazolone,
phenacetin(oracetophenetidin).
Althoughchemicallyunrelated,thedrugsinthesefamilieshav
e the ability to relieve mild to moderate pain
throughactionsthatreduceinflammationatitssource.
15. SALICYLICACID
�SalicylicacidhastheformulaC7H6O3.
�itiscolorlesscrystallineorganicacid.
� Salicylic acid as a medication is used most commonly to help remove the
outerlayer of the skin. As such, it is used to treat warts (Warts are typically
small,rough, andhardgrowths thataresimilarincolortothe restof theskin)
psoriasis(Psoriasis is a long-lasting autoimmune disease characterized by
patches ofabnormalskin.Theseskinpatchesaretypicallyred,itchy,and
scaly),dandruff,acne,ringworm(Dermatophytosis,alsoknownasringworm, isa
fungalinfectionoftheskin).
17. PHENACETIN
Phenacetin(oracetophenetidin)is apain-relievingand fever-reducingdrug,whichwas
widely used between its introduction in 1887 and the 1983 ban imposed
bytheU.S.Foodand DrugAdministration.
Mechanismofactions;
itsanalgesiceffects areduetoitsactionson thesensory tractsof
thespinalcord.Inaddition,phenacetinhasadepressantactionon theheart,whereitactsas
a
negativeinotrope.Itis an antipyretic,actingon thebraintodecreasethe temperatureset
point. It is also used to treat rheumatoid arthritis (Rheumatoid arthritis (RA) is
along-term autoimmune disorder that primarily affects joints. It typically results
inwarm, swollen,and painfuljoints).Itis metabolizedinthe body
toparacetamol(acetaminophen),whichis alsoaclinicallyrelevantanalgesic.
Ahand affectedbyrheumatoidarthritis
19. PHENACETINDERIVATIVES;
Acetaminophen (a derivative of phenacetin) and the aspirin-
likedrugs,ornonsteroidalanti-
inflammatorydrugs(NSAIDs),which include compounds such
as ibuprofen, naproxen, andfenoprofen.
20. PYRAZOLONEDERIVATIVES
�Pyrazolone derivatives, with some exceptions, are
nolongerwidelyusedinmanycountries,becauseoftheirte
ndencytocauseanacuteinfectionknown
as agranulocytosis (Agranulocytosis, also known
asagranulosis or granulopenia, is an acute
conditioninvolving a severe and dangerous leukopenia
(loweredwhite blood cell count), most commonly of
neutrophilscausing a neutropenia in the circulating
blood. It is aseverelackofonemajor classofinfection-
fightingwhitebloodcells).
21. MECHANISMOFACTIONS
�Inhibitionofthesynthesisofprostaglandins;
�Aspirin and NSAIDs appear to share a similar molecular
mechanismofaction—namely,inhibitionofthesynthesis
ofprostaglandins(naturalproductsofinflamedwhitebloodcells)thatinduc
e the responses in local tissue that include pain andinflammation.
� In fact, aspirin and all aspirin-like analgesics, including
indomethacinand sulindac, which are derived from a heterocyclic
organiccompound known as indole, inhibit prostaglandin synthesis
andrelease.
24. CONTINUE…
�AdvantageofCOX-2inhibitors;
The use of COX-2 inhibitors (e.g., rofecoxib, celecoxib) seems
toresult in less gastric ulceration than occurs with other anti-
inflammatory analgesics, particularly aspirin. However, COX-
2inhibitorsdo notreducetheabilityofplateletsto
formclots,abenefitassociatedwithaspirinandothernonselectiveCOX
inhibitors.
26. CONTINUE…
�Despite this, acetaminophen is a popular mild analgesic
andantipyretic and is a suitable alternative to aspirin for patients
whodevelopseveresymptomsofstomachirritation,becauseitisnotash
armful tothe gastrointestinaltract.
30. PEPTIC ULCERS, LIVER DAMAGE
&RENALTOXICITY
�Inhibition of prostaglandin synthesis may result in other serious
sideeffects, such as peptic ulcers and a reduced ability of platelets
in thebloodto aggregateandformclots.
�Liver damage occasionally occurs after administration
ofacetaminophen.
�Renaltoxicityissometimesseenwith useofNSAIDs.
32. REYESYNDROME
�Aspirin is also thought to be a causative agent of Reye syndrome, a
rareandseriousdegenerativediseaseof
thebrainandfattytissueoftheliverthataccompaniescertainviralinfectionsin
childrenandyoungadults.
Someaspirin-likeanalgesicsalsohavespecifictoxiceffects
33. OPIOIDANALGESICS
�The term opioid has been adopted as a
generalclassification of all those agents that share
chemicalstructures, sites, and mechanisms of action
with
theendogenousopioidagonists(endogenoussubstancesare
thoseproducedinsidethehumanbody).
38. ADDICTIVEDRUGS
�Although interest in these drugs had always been
highbecause of their value in pain relief and because
ofproblemsofabuseandaddiction,interestintensifiedinthe19
70s and ’80s by discoveries about the naturallyoccurring
morphine like substances, the
endogenousopioidneuropeptides.
39. OPIUM
�Opiumis thepowder from thedried
juiceofthepoppyPapaversomniferum.
�When taken orally, opium produces sleep and induces a state
ofpeacefulwell-being.
�ItsusedatesbackatleasttoBabyloniancivilization.
�In the early 19th century opium extract was found to contain more
than20distinctcomplexorganicbases,calledalkaloids,ofwhichmorphine,
codeine, and papaverine are the most important. These
purealkaloidsreplacedcrudeopiumextractsintherapeutics.
40. MECHANISMOFACTION
�In the 1950s several new morphine like drugs
weredeveloped. Despite the increase in the number
ofcompoundsavailableforpainrelief,however,littlewasu
nderstoodof theirsitesandmechanisms ofaction.
41. ENKEPHALINS;
�The first real breakthrough came from the discovery,
byneuroscientistsJohnW.HughesandHansW.Kosterlitzatt
he University of Aberdeen in Scotland, of two
potentnaturally occurring analgesic Penta peptides
(peptidescontaining five linked amino acids) in extracts
of pigbrain. They called these compounds enkephalins,
andsincethenatleastsixmorehavebeenfound.
45. CONTINUE…
Relieveabdominaldistress;
�Opioids are also able to relieve the abdominal distress and fluid
lossofdiarrhea.
�Usedindrugtherapeutics;
�Several commonly used natural or synthetic derivatives of morphine
areusedindrugtherapeutics.
�Codeine;
�Codeine, a naturally occurring opium alkaloid that can be
madesynthetically,isausefuloralanalgesic,especiallywhenusedin
combinationwith aspirin.
46. �Meperidine
CONTINUE…
Meperidine was an early synthetic analog of morphine, marketed
underthetradename Demerol,
thatwasoriginallythoughttobeabletoprovidesignificant short-lasting
analgesia and little or no addiction because of
itsshorteneddurationofaction;however,thisbeliefprovedfalse.
�Methadone;
Methadone, a synthetic opioid analgesic, has long-lasting
analgesiceffects(sixtoeighthours)when
takenorallyandisusedtomoderatetheeffectofwithdrawalfrom
heroinaddiction.
47. OPIOIDANTAGONISTDRUGS;
�Among the opioid antagonist drugs, naloxone and its longer-
lastingorally active version, naltrexone, are used primarily to
reversemorphine overdoses and to reverse the chemical stupor of a
widervariety of causes, including alcohol intoxication and anesthesia.
Inopioid overdoses, these drugs provide recovery within minutes
ofinjection. They can, however, also precipitate severe
withdrawalreactionsin apersonaddictedto opiates.
49. Narcoticsapplicationsindentistry;
�Narcotics analgesics are extremely effective in
reducingacutedentalandpostoperativepain
�The narcotics analgesics have established a niche for
thetreatment of pain in those situations where the
NSAIDsarelesseffective.
�Hydrocodone, oxycodone. Codeine and
occasionallymeperidinearethenarcoticsusedto
treatdentalpain.
