Post on 07-May-2015
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ANALGESICS
ANALGESIC
A drug that selectively relieves pain by acting on CNS or on peripheral pain mechanisms without significantly altering consciousness
ALGESIA or PAINIt is an illdefined, unpleasent sensation,
usually evoked by an external or internal noxious stimulus
PAIN RECEPTOR Pain receptor in our bodies are nerves that transmit pain.
These are free nerve endings located in various body tissues that respond to thermal, mechanical, & chemical stimuli.
When tissue becomes injured, they release chemicals called prostaglandins and leukotrienes that make the pain receptor more sensitive and these causing pain.
Types of PainPAINAccording to sourceVisceralSomatic
NeuropathicAccording to chronicity
ChronicAcute
Therapeutic management of painClassification: Peripheral (miscellaneous): -Causal -Non causal Central: -Narcotic -Non narcotic
Peripheral AnalgesicCausal: -Treat the cause
eg:- atropine
Non-causal: -Not treat the cause
Examples:1- Local anesthetics (for
superficial tumor)2- Counter-irritant (apply pain
that counteract or mask the original one e.g. acupuncture)
Central AnalgesicOpioids:
Morphine & morphine like drugs
NSAIDs: 1- Aspirin
2- Paracetamol3- Diclofenac4- Piroxicam5- Ibuprofin6- Ketoprofin
OPIOID ANALGESIC“Opium” is a Greek word meaning “juice,” or the
exudates from the poppy.Opium is extracted from poppy seeds (Paper
somniforum)“Opioid” is a natural or synthetic drug that binds
to opioid receptors producing agonist effects.
Fresh capsule of opium poppy Cut capsule showing latex exuding from cut
Classification Chemically
Phenanthrene groupEg: Morphine
Benzolisoquinoline groupEg: Papaverine
MORPHINE• Morphine is the most important alkalloid of opium.
• Many new opioids have been synthesized but none of them are superior to morphine as an analgesic.
• It is the protype of this group.
Mechanism of Action Opioids exert their major effects by interacting with opioid receptors in the CNS Opioids activate 7- transmembrane GPCRs located pre-symaptically and post-symaptically along pain
transmission pathways. High densities of opioid receptors known as mu, delta and kappa are found in the dorsal horn of the spinal
cord and higher CNS centers. Most currently used opioid analgesics act mainly at mu- opioid receptors Morphine acts at kappa receptors in lamina 1 and 11 of the substantia Granulose of the spinal cord and
decreases the release of substance p, which is modulates pain perception in the spinal cord. Opioids have an onset of action that depends on the route of administration . Opioids causes hyper polarization of nerve cells , inhibition of nerve firing and presynaptic inhibition of
transmitter relea Cellular effects of these drugs involve enhancement of neuronal potassium efflux ( hyperpolarizes neurons
and makes them less likely to respond to a pain stimulus ) and inhibition of calcium influx ( decreases neuro- transmitter release from neurons located along the pain transmission pathway )
Opioids relieve pain both by raising the pain threshold at the spinal cord level and more importantly by altering the brains perception of pain
Pharmacological actions Analgesia Respiratory depression Cough suppression Vagal stimulation (bradycardia) Sedation & hypnosis Hypothermia Itching Physical & pshycological dependence Euphoria Histamine release , hypotension….etc
Adverse effects• Morphine can produce a wide range of adverse effects like nausea, vomiting, dizziness,
mental clouding, respiratory depression, constipation, dysphoria, urinary retention, & hypotension, allergic reactions.
• Tolerance- Repeated administration of morphine results in the development of tolerance to some of its effects including respiratory depression, analgesia, sedation, etc .
• Dependence- Opium has been a drug of addiction for many centuries. Its ability to produce euphoria makes it a drug of addiction. Opioids produce both physiological & pshycological dependence. Manifestations are lacrimination, sweating, yawning, anxiety, restlessness..etc.
NSAIDsNon steroidal anti-inflamatory drugs are
aspirine-type or non-opioid analgesics. In addition they have anti-inflamatory,
anti pyretic & uricosuric properties without addiction liability.
The active principle is salicin, that is converted into salicylic acid in body.
Classification
Non selective COX inhibitor
• Salicylic acid derivatives. Eg: aspirine
• Para aminophenol derivatives. Eg: paracetamol
• Pyrazolone derivatives. Eg: Sphenylbutazone
• Indole acetic acid derivatives. Eg: sulindac
• Arylacetic acid derivatives. Eg: diclofenac
• Propionic acid derivatives. Eg: ibuprofen
• Anthralinic acid derivatives. Eg; flufenamic acid
• Oxicams. Eg: piroxicam• Alkanones. Eg: nabumetone
Selective COX-2 inhibitors• Nimesulidde,
celecoxib, rofecoxib…etc
Mechanism of action
Arachidonic acid
COX-1 COX-2
Leukotrienes\Prostaglandin
s
Prostaglandins
Primarily support platelet function
Primarily protect GI-tract mucosa
Primarily mediate inflamation, fever,
pain
NSAIDs COX-2 inhibitors
Pharmacological actions• Analgesia
• Antipyretic actions
• Anti-inflamatory actions
• Respiration stimulation
• Metabolic effects
• Immunological effects
• Uric acid excretion
• Blood- delayed clotting time
Adverse effects Analgesics doses are usually well tolerated but anti-inflamatory doses are
usually associated with adverse effects whed used for a long period.A. G.I tract:- Epigastric distress, nausea, vomiting, erosive gastritis, peptic
ulcer, increase occult blood loss in stools are commonB. Allergic reactions are not common and may be manifested as rashes,
photo sensitivity..etcC. HaemolysisD. NephrotoxicityE. Reye’s syndromeF. Salicylism G. Acute salicylate intoxication
Analgesics used in deintistry
• Non opiod analgesics are mostly used for mild to moderate pain.
• NSAIDsCOX1 & COX2:
Ibuprofen, aspirin, ketrolac, diclofenac COX-2:
celecoxib, rofecoxib, nimesulide.
Acetaminophen• Dose:
-Adult: 0.5 – 1g every 4-6 hrs.-6-12 years: 250-500mg every 4-6hrs.-1-5 years: 150-250mg every 4-6hrs.
• Contraindication: Renal failure, asthma, liver failure.
Nimesulide• Indication:- Acute pain
• Dose:- 100mg twice a day
• Contraindication:- Renal failure, asthma, liver failure
OPIOIDS Although opiod as a class are
effective analgesics, some commonly formulation shows poor analgesic efficacy for dental pain, and is not used for their adverse effects.
Tramadol• Tramadol is a synthetic centraly acting
analgesic indicated to moderate to moderately severe pain.
• Dose:- 50-100mg every 4-6 hours.(400mg/day- maximum)
Combination!!• Analgesic monotherapy has shown
equivocal success in treating dental pain.
• The goal of combining analgesics with different mechanisms of action is to use lower doses of the component drugs.
Acetaminophen combination
• Acetaminophen is an effective analgesic for mild pain, but to manage more severe pain it typically is combined with codeine or one of its derivatives.
• Acetaminophen 1000mg combined with codeine 60mg.• Acetaminophen 1000mg combined with oxycodone 10mg.• Acetaminophen 650mg combined with tramadol 75mg.• Acetaminophen 500mg combined with hydrocodone 7.5mg.
NSAIDs Combination• Ibuprofen 400mg combined
with codeine 60mg.• Ibuprofen 400mg combined
with oxycodone 10mg.• Ibuprofen 400mg combined
with hydrocodone 15mg.• Ibuprofen is also combined
with tramadol.
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