Non steroidal anti-inflammatory drugs CLASSIFICATION & individual drugs

1. NSAIDS
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2. CONTENT
• INTRODUCTION
• HISTORY
• BIOSYNTHESIS OF PGs
• NSAIDS CLASSIFICATION
• COMMON FEATURES
• INDIVIDUAL DRUGS
• SCREENING METHODS FOR ANALGESIC DRUGS
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3. INTRODUCTION
• Pain is an unpleasant sensory & emotional experience associated with actual /
potential tissue damage.
• Steps in pain pathway include: Transduction, transmission, modulation &
perception.
• An analgesic is a drug that selectively relieves pain sensation by acting on CNS /
on peripheral pain mechanisms without altering consciousness.
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4. Major classes of analgesic drugs include
OPIOID ANALGESICS NSAIDs
Act via opioid receptors Acts mainly by inhibiting PG synthesis
Produce CNS depression -
Cause addiction, physical dependence &
tolerance
-
- Produce gastric irritation
- Have anti inflammatory & anti pyretic action
Used in visceral / severe pain Used in mild to moderate integumentary pain
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5.  NSAIDs are m/c prescribed category of drugs worldwide in the treatment of fever,
pain & inflammation in many conditions.
 Chemically heterogeneous group of compounds , which share certain therapeutic
action & adverse effects.
 Also known as nonnarcotic, nonopoid / aspirin like analgesic.
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6. HISTORY
• Willow bark was used as a medicine for many centuries to relieve fever.
• 1839-Salicylic acid was isolated
• 1875-Sodium salicylate was used for fever & pain
• 1899-Hoffmann developed Aspirin
• 1963-lndomerhacin was introduced
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7. BIOSYNTHESIS OF PGs
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8. NSAIDS
CLASSIFICATION
Non selective COX
inhibitor
Preferential COX-2
inhibitor
Selective COX-2
inhibitor
Analgesic antipyretic
with poor
antiinflammatory
action
Paracetamol
Nefopam
Celecoxib
Etoricoxib
Parecoxib
Nimesulide
Diclofenac
Aceclofenac
Meloxicam
Etodolac
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Non selective COX inhibitor
Salicylic acid
derivative
Aspirin
Propionic acid
derivatives
Ibuprofen
Naproxen
Ketoprofen
Flurbiprofen
Fenamate Mephenamic
acid
Acetic acid
derivatives
Ketrolac
Indomethacin
Nabumetone
Enolic Acid
derivatives
Piroxicam
Tenoxicam

9. 9
Classification based on anti inflammatory action
Markred anti
inflammatory
Moderate anti inflammatory Weak anti inflammatory
1.Salicylic acid
derivative-Aspirin
2.Acetic acid derivatives
Ketrolac
Indomethacin
Nabumetone
3.Enolic Acid derivatives
Piroxicam
Tenoxicam
1.Propionic acid derivatives
Naproxen>Flurbiprofen
>Ibuprofen=
Ketoprofen
2.Diclofenac
1.Fenamate
Mephenamic acid
2.Paracetamol

10. COMMON FEATURES-MOA
• All NSAIDs inhibit COX enzyme in arachidonic acid cascade thus blocking the synthesis of
prostanoids
• COX in 2 isoforms:
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COX-1 COX-2 COX-3
Constitutive to the cell Inducible- generated by
mediators of inflammation
Splice variant of COX-1 present
in cerebral cortex & heart
-Serves house keeping function
Eg: Gastro protective
Constitutive to the brain,
endothelium & JG cells of kidney
Involved in pain & fever.
Pro carcinogenic due to inhibitory
activity on apoptosis, stimulation
of cell migration & invasiveness

11. COMMON FEATURES- Beneficial action
1. Analgesia
2. Antipyresis
3. Anti-inflammatory action
4. Antithrombotic action
5. Closure of Ductus arteriosus in newborn
6. Relief from dysmenorrhoea
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12. Analgesia
• PGE2 & PGI2 is a hyperalgesic which act by :
- pain receptor sensitivity to algesic substances / pain mediators like histamine, 5-HT , IL-1,
TNF-α, Substance P & bradykinin.- thus helping pain transduction.
-In spinal cord & higher centers promotes transmission of pain sensation to brain
• NSAIDS inhibits both the components of pain.
 Peripheral component: By inhibiting COX-2-More effective against integumentary pain
associated with inflammation & tissue injury.
 Central Component: Inhibition of PGs release in spinal dorsal horn & subcortical region
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13. Antipyresis
• Fever is produced by pyrogens - ILs, TNFα & IF which induce PGE2 production in
hypothalamus-raise its temperature set point.
• NSAIDs block the action of pyrogens -by inhibiting PGE2 production - resets the
hypothalamic thermostat.
• Fever reduction by promoting heat loss by sweating & cutaneous vasodilation.
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14. Antiinflammatory
• By predominantly block COX-2 mediated PG synthesis & also COX-1 in initial stages
• vasodilatory PGE2 & PGI2
• Inhibiting other mediators like LT, PAF & cytokines etc
• Inhibiting adhesion molecules on endothelial cells – ECAM-1 & ICAM-1
• Inhibition of expression of Selectins & Integrins on inflammatory cells
• Inhibition of growth factors like GM-CSF, IL-6, lymphocytes transformation factors & TNF α
• Stabilization of lysosomal membrane of leukocytes.
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15. Dysmenorrhoea
• Caused by release of PGF2α
• Uncoordinated uterine contraction causing -Intermittent ischaemia of myometrium –
cramps
• NSAIDs - decrease PG release
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16. Closure of Ductus arteriosus
• DA is a shunt connecting the pulmonary artery to the aortic arch
• Maintained by local PGE2 produced by COX2
• Closes at birth
• Failure to close/PDA – small doses of NSAIDs (aspirin or indomethacin)
• NSAIDs C/I in pregnancy near term – premature closure of DA
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17. COMMON FEATURES- Toxicities
• Gastric mucosa damage
• Bleeding
• Limitation of renal blood flow : Na & water retention
• Delay/prolongation of labour
• Asthma & anaphylactoid reactions in susceptible individuals
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18. Gastric Mucosal damage
• COX-1 mediated synthesis of PGE2 & PGI2 have gastro protective effects- Mucus & HCO3
Acid
•NSAIDs inhibit COX-1– promote mucosal ischemia, erosion/ulceration & blood loss
– Also back diffusion of H+ in gastric mucosa
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19. Antiplatelet aggregator
• TXA2 produced by platelets is pro-aggregator (COX-1)
• PGI2 produced by vascular endothelium is anti-aggregator
• Most NSAIDs - effects on TXA2 predominates as the platelets lack nucleus , while
endothelium produce PGI2– prolonged bleeding time
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20. Renal effects
Conditions leading to hypovlaemia, renal perfusion & Na loss induce PG which causes
 Renal vasodilation ( GFR) (COX-1)
 Opposes ADH- water excretion
 Na & K excretion (COX-2)
 Inhibitory effect on Cl reabsorption.
 Facilitates renin release
NSAIDs opposes these effects - action become significant CHF, cirrhosis & renal impairment ,
Patent on antihypertensives & diuretics (renal insuffecency, Na+ retention &edema, papillary
necrosis )
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21. Analgesic nephropathy
• Caused by prolonged & regular/habitual use of high dose of NSAIDs/ combination
of NSAIDs
• Resulting in slowly developing renal failure characterized by chronic interstitial
nephritis/CIN, renal papillary necrosis & shrinkage of kidney
• Can progress to ESRD
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Inhibition of
vasodilatory
PGs
Medullary
hypoxia/ischemia
-
pappilary necrosis
tubular
atrophy&
interstitial
fibrosis

22. Anaphylactoid reactions
• Due to inhibition of COX cause diversion of arachidonic acid to LTs production
• Aspirin, ibuprofen & indomethacin precipitates asthma, angioneurotic swellings,
urticaria or rhinitis in certain susceptible individuals.
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23. SALICYLATES
• ASPIRIN is acetylsalicylic acid
• Prototype NSAID – converted in the body to salicylic acid.
• It acetylates serine residue of COX, irreversibly inhibiting it.
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24. PHARMACOLOGICAL ACTION
1.Analgesic, Antipyretic &Anti-inflammatory action
- Weaker analgesic than Morphine -Not much effective in visceral & ischemic pain
- Promote heat loss but does not heat production
- Anti-inflammatory action by COX inhibition & free radical scavenging
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25. 2. GIT
a)Ion trapping -Having pKa of 3.5 it remains unionized in acidic stomach & rapidly
absorbed to mucosal cell ( pH 7.1), but upon absorption becomes ionizes & indiffusible
.
b)Back diffusion of acid
 Irritant to mucosa causing epigastric distress, nausea & vomiting
 Focal necrosis of mucosa & arteries –erosive gastritis , ulceration, congestion &
micro haemorrhages – Occult blood loss in stools – haematemesis
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26. 3. Hematologic effects:
 At low dose it inhibit TXA2- inhibiting platelet aggregation– Bleeding time-lasts for a
week till new platelets are formed
 Prolonged use – clotting factors synthesis
4. Metabolic effects( at antiinflamatory dose):
 cellular metabolism by uncoupling of oxydative phosphorylation → O2 consumtion,
CO2 production & heat production
 utilization of glucose – blood sugar ( especially in diabetic) & glycogen depletion
 Toxic doses: Hyperglycaemia ( due to central sympathetic stimulation)
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27. 5.Respiration:
 Low dose -↑ CO2 → stimulates respiration
 In Poisoning - Hyperventilation f/b depression of respiratory center
6.Acid-base Balance at Anti-inflammatory doses
 Direct stimulation of RC - Respiratory stimulation , there is wash out of CO2–
Respiratory alkalosis – Compensated by excretion of HCO3– Compensated
Respiratory Alkalosis (Salicylism)
 Still Higher doses: Respiratory depression – retention of CO2 – Respiratory acidosis .
 Toxic dose: production of metabolic acids – pyruvic acid, lactic acid and dissociated
salicylic acid result is – Uncompensated Metabolic acidosis ( Salicylate poisoning)
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28. 7.CVS: – High doses- CO
– Toxic doses – VMC depressed– CCF in low cardiac reserve patients.
8. Urate Excretion:
 Dose < 2 gm/day : urate retention & antagonise uricosuric effect of probenecide.
 >5 gm/day – urate excretion by inhibiting its reabsorbtion, but cannot be used in
gout as high dose cannot be tolerated.
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29. Pharmacokinetics
• Absorbed from stomach & SI
• Its poor water solubility is the limiting factor in absorption.
• Converted to salicylic acid in gut, liver & plasma
• 80-85% PPB - can cross placenta
• Metabolized in liver by conjugation with glycine – salicyluric acid
• T1/2 life is 15-20 minutes
-anti inflammatory dose T1/2 is 8 – 12 Hrs
- High doses have long t1/2 as metabolic processes get saturated
• Excreted as glomerular filtration & tubular secretion
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30. 31
Effect Dose/day
Antiplatelet 75-150mg
Analgesic, Anti pyretic .3-.6g
Antiinflammatory 3-5g
Hyperventilation leading to
Respiratory alkalosis
5-10g
Metabolic acidosis, fever,
dehydration & respiratory
depression
10-20g
Convulsion coma & death >20g

31. Aspirin-A/E
1 Severe GI disturbances Epigastric distress, n, v
gastric mucosal damage , peptic ulceration & occult
blood in stools
2 Hypersensitivity reaction rash, urticaria, rhinorrhoea, angioedema, asthma
and anaphylactoid reaction
3 Acutely administered high dose/
chronic use resulting in high con in
blood.-50-75mg/dl
Salicylism: (3-5 gm/day)
Respiratory alkalosis, dizziness, tinnitus, vertigo,
reversible impairment of hearing & vision,
Excitement, mental confusion & hyperventilation
4 Hepatotoxicity TA – seen in children with RA
5 Nephrotoxicity Na+ & water retention, CRF, nephropathy
6 Reye`s Syndrome – rare disease of hepatic encephalopathy when aspirin is given to
children in viral conditions of influenza & varicella
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32. • Acute salicylate poisoning – m/c in children
 Fatal dose in adults is 15- 30 g
 Lower in children.
 Manifestations are:
-Vomiting, dehydration, metabolic acidosis
- acidotic breathing, hyper/hypoglycaemia.
-petechial hemorrhages
-restlessness, delirium, hallucinations, hyperpyrexia, convulsions, coma & death
due to respiratory failure + CV collapse.
 Treatment is symptomatic & supportive.
-gastric lavage, external cooling & i.v. fluid with Na, K+, HCO3-
- glucose according to need determined by repeated monitoring.
-Urine alkalization - Vit K if bleeding occurs
- Haemodialysis (>90mg/dl)
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33. Therapeutic uses
1.Analgesic (.3-.6gm 6- 8 Hrly) : Headache, migraine, backache, myalgia, joint pain,
toothache, neuralgia , dysmenorrhea etc.
2.Antipyretic (Paracetamol being safer is generally preferred)
3. Acute rheumatic fever : (4-5 g/day)
 First drug to be used in all cases
 Dose reduction after 1 week
 Maintenance doses are continued for 2-3 weeks
 W/d should be gradual over the next 2 weeks.
4. Osteoarthritis- Paracetamol is preferred
5. Rheumatoid arthritis (3- 5 g/day)-Poorly tolerated for long periods- newer NSAIDS
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34. 6. Post MI & Post stroke
 For prophylaxis purpose to prevent re-infarction (75 - 150 mg) due to platelet/ arterial
thrombi.
 New onset, sudden worsening angina
 Reduces TIA & lowers incidence of stroke
7. Prevention of preeclampsia in PIH
 Imbalance between synthesis of TXA2 & PGl2 is believed to be causative in PIH and
preeclampsia.
 Aspirin 80- 100 mg/day administered from 12th week of gestation till child birth.
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35. 8. Familial colonic polyposis: aspirin and other NSAIDs suppress polyp formation.
9.Prevention of colon cancer: Colonic tumors express large quantities of COX-2.
10.Topically used as
 counterirritant in muscle & joint pain ( oil of winter green/ methyl salicylate),
 keratolytic in case of corn (Salicylic acid)
 Epidermophytosis (With benzoic acid)
 Analgesic & sunscreen( Trolamine salicylate)
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36. Contraindications
1. Patients sensitive to aspirin.
2. Peptic ulcer & bleeding d/o
3. Children below 12yrs–Reye’s syndrome
4. Bronchial asthma
5. Chronic liver diseases- hepatic necrosis
6. Diabetes
7. Patients with poor cardiac reserve & in conditions where increased circulatory
volume may cause problem- CHF , HTN
8. G6-PD deficiency
9. Stop 1 week prior to surgery,
10. Near term pregnancy, breast feeding mothers
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37. DRUG INTERACTION
Warfarin, sulfonylurease,
phenytoin, valproate and
methotrexate
Competition from PPB Toxicity
Methotrexate, AG, Li, Digoxin Decreases renal excretion Toxicity
Probenecid 1.antagonizes uricosuric action
2. Inhibits tubular secretion of
uric acid
Worsening of gout
Corticosteroids, anticoagulants
& ethanol
Increase GI bleed
Anti-hypertensive (BB, ACE#) NSAIDs cause
vasoconstriction by inhibiting
PGI2 produced by kinin
Antihypertensive effects are
decreased
Diuretics: Na, K , Cl & water retention Reduce the diuretic action
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38. Propionic acid derivatives
Ibuprofen
• Analgesic, antipyretic & anti-inflammatory- efficacy is lower than aspirin
• Antiplatelet activity – short with Ibuprofen but longer with naproxen .
• A/E:
 Better tolerated than aspirin & indomethacin – milder gastric discomfort, n,v–m/c
 CNS effects - headache, dizziness, tinnitus & blurring of vision
 Precipitates aspirin induced asthma
• Uses
– Dysmenorrhoea
-Rh. Arthritis, OA & musculoskeletal d/o (Pain is the main component)
-Soft tissue injury, fractures, vasectomy, tooth extraction,
postpartum & post op pain
• C/I : Pregnancy & Peptic ulcer
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39. Naproxen
• Most potent propionic acid derivative
• Potent anti-inflammatory activity - inhibiting leucocytic migration
• t1/2: 12-16 hrs
• Uses:
Acute gout, Rheumatoid arthritis, Ankylosing spondylitis.
• A/E:
-Gastric bleeding is m/c than with ibuprofen.
-Lower thrombotic risk than diclofenac, etoricoxib etc. (Dose Reduction In Elderly)
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40. Fenamates - Mephenamic acid
• Analgesic, antipyretic & weak anti-inflammatory
• A/E: Diarrhoea, epigastric distress
skin rash, dizziness & other CNS manifestations
• Uses: as analgesic in muscle, joint & soft tissue pain ,dysmenorrhoea.
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41. Enolic acid derivatives- Piroxicam
• Long acting potent anti-inflammatory NSAID with good analgesic-antipyretic action
– free radicals & IgM rheumatoid factor & leucocyte chemotaxis
• A/E:
 GI side effects are more than ibuprofen
 low doses -better tolerated & less ulcerogenic than indomethacin.
 higher doses -ulcer and g.i. bleeding are frequent .
 Rashes , pruritus & serious skin reactions are possible.
 Edema & reversible azotaemia
• Uses: Long term anti-inflammatory – rheumatoid arthritis, osteo-arthritis, ankylosing
spondylosis, acute gout etc.
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42. Acetic acid - Indomethacin
• Indole acetic acid derivative
• Potent anti-inflammatory & prompt antipyretic
–Also inhibit neutrophil motility
• A/E: High incidence of gastric & CNS side effects (COX-1 related)
- gastric irritation, nausea, anorexia, bleeding & diarrhoea
-Frontal headache(Analgesic causing pain), dizziness, ataxia, mental confusion,
hallucination, depression & psychosis
-Increased risk of bleeding
- Precipitate asthma in sensitive people
• C/I: machinery operators, drivers, psychiatric & epileptic patients, kidney disease,
pregnancy & children
• Use: Reserve drug - ankylosing spondylitis, destructive arthropathies, psoriatic arthritis,
Acute gout, malignancy associated fever,
medical closure of PDA , Bartter’s syndrome
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43. Acetic acid -Ketorolac
• Aryl acetic acid derivative that is a potent analgesic –equal efficacy with Morphine
Short term management of moderate pain.
Concurrently used with morphine in severe pain (reduce dose-opoid sparing).
• Uses: Given i.m & orally
- Post-operative, dental, musculo-skeletal pain
- Renal colic, migraine & pain due to bony metastasis
• A/E: Nausea, abdominal pain, dyspepsia, ulceration, dizziness, nervousness, pain in
injection site, rise in serum transaminase, fluid retention etc
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44. Preferential COX-2 inhibitors
• Nimesulide
• Diclofenac
• Aceclofenac
• Meloxicam
• Etodolac
Advantage: less gastric ulceration & bleeding
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45. Nimesulide
• Weak PG synthesis inhibitor
– Other Mechanisms:
 Reduced superoxide generation by neutrophils & macrophage.
 inhibition of PAF, TNFα release
 inhibition or metalloproteinase activity in cartilage.
• Uses : (In short lasting painful inflammatory conditions)sports injuries, sinusitis &
other ENT d/o, dental surgeries, renal colic, bursitis, postoperative pain, OA &
fever
• A/E: Gastrointestinal(epigastric pain, nausea, loose motion)
Dermatological( Rash , pruritis)
Central (somnolence &dizziness)
Fulminant hepatic failure
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46. Diclofenac
• Analgesic-antipyrretic & antiinflammatory with efficacy similar to naproxen
 Reduced Neutrophil chemotaxis & reduced superoxide generation
 No antiplatelet action (COX-1 sparing)
• Uses: Most widely used drug – RA, OA, ankylosing spondylitis , bursitis,
toothache, dysmenorrhea, renal colic, post trauma
and post inflammatory conditions
• A/E: Mild epigastric pain, nausea, headache, dizziness & rashes
Elevation of serum amino transferase – less gastric ulceration & bleeding
Risk of heart attack and stroke
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47. Selective COX-2 inhibitors
 Advantage: Less gastric mucosal damage(COX-1 sparing)
Do not precipitate asthma
 Disadvantage: Increase chances of thrombus(COX-2 mediated PGI2 production )
Na & water retention, Pedal edema, precipitation of CHF & rise in BP
Delay gastric ulcer healing
 C/I : patients with h/o IHD, CRF, HTN & CVD
 Used (only in patients at hight risk of peptic ulcers, perforation/ bleed.)
 Celecoxib- OA & RA
 Etoricoxib (Longst acting coxib)- OA, RA, acute gouty arthritis, AS, dysmenorrhea
& acute dental surgery
 Parecoxib (Prodrug) – Post operative/ similar short term pain
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48. Paracetamol (acetaminophen)
• Deethylated active metabolite of Phenacetin
• The central analgesic action & antipyretic action is like aspirin- Selective COX3
inhibition in brain
• No peripheral anti-inflammatory action - inability to inhibit COX-1 in the
presence of peroxides which are generated at sites of inflammation by leukocytes.
• Do not affect respiration /acid base balance /cellular metabolism unlike aspirin–
No gastric toxicity or platelet function alteration/CVS effects
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49. Paracetamol
• Kinetics: orally absorbed, 1/4th PPB, t1/2: 2-3 hours; Metabolism by conjugation with
glucoronic acid & sulfate. Conjugates are excreted rapidly in urine
•Safe & well tolerated
• ACUTE PARACETAMOL POISONING
- m/c in Children – low hepatic glucuronidation conjugation capacity
- >10 gm in adults is toxic, >250mg/kg is fatal
- Manifestations: Nausea, vomiting, abdominal pain & liver tenderness
After 12 – 18 hours – centrilobular hepatic necrosis, renal tubular necrosis & hypoglycaemia
progressing to coma
– Jaundice after 2 days
– If plasma levels are still high– fulminating hepatic failure & death
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50. Paracetamol toxicity
Large dose of Paracetamol--- glucoronidation
capacity gets saturated
Highly reactive minor
metabolite N-acetyl-p-
benzoquinoneimine (NAQBI)
produce ––– normally
detoxified by conjugation with
glutathione
Hepatic glutathione
depleted at higher dose
– metabolites bind
covalently to proteins
in liver cells & renal
tubular cells – necrosis 52

51. • Treatment: Early cases - Induction of vomiting /Gastric lavage
-activated charcoal to prevent absorption
– N-acetylcysteine – 150 mg/kg iv for 15 min in 5% D
– F/B 50mg/kg iv infusion in 5% D over 4 hours
–F/B 100mg/kg iv in 5%D over 16hours to replenish
glutathione store & prevents further binding with cellular contents
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52. Paracetamol-Uses
• Headache, mild migraine, musculoskeletal pain & dysmenorrhoea .
• 1st choice in osteoarthritis
• Safest antipyretic except in case of fever due to heat stroke
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53. • Advantages –
1)Lesser gastric irritation, ulceration and bleeding (can be given in ulceration)
2) Does not prolong bleeding time
3) Hypersensitivity rarely
4) No metabolic disturbances
5) can be given in all age group – pregnancy- lactation
6) No significant drug interactions
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54. Choices of NSAIDS
1. Mild to moderate pain – Paracetamol or low dose Ibuprofen
2. Post operative acute short lasting pain – Ketorolac, Propionic acid derivatives, diclofenac
or nimesulide
3. Acute musculo-skeletal, osteoarthritic or injury pain – Paracetamol or propionic acid
4. Exacerbation of Rh. Arthritis, acute gout, ankylosing spondylosis – naproxen, piroxicam,
indomethacin
5. Gastric intolerance to NSAIDS - Selective COX-2 inhibitors
6. H/o asthma – nimesulide or selective COX-2 inhibitors
7. Hypertension or risk of heart attack – avoid COX-2 inhibitors , propionic acid
derivatives & low dose aspirin
8. Paediatric – paracetamol, ibuprofen & naproxen
9. Elderly – low dose of NSAIDS
10. Pregnancy – Paracetamol
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55. INVIVO SCREENING METHODS FOR ANALGESIC
DRUGS
 Models using thermal stimuli:
– The tail flick model using radiant heat/immersion of the tail in hot water
– Hot plate method
 Models using electrical stimuli:
– Electrical stimulation of the tail
– Stimulation of the tooth pulp
 Model using mechanical stimuli:
-Haffner’s tail clip method
 Models using chemical stimuli:
– Formalin test
–Acetic acid induced Writhing test
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56. Tail flick model using radiant heat
• Principle: Application of thermal radiation ( noxious stimuli )to the tail provoke
w/d of the tail by vigorous movement. Time taken for w/d of the tail from heat
source is referred as “tail flick latency”. Lengthening of this reaction time after
administration of drug interpreted its analgesic action.
• Procedure:
 Mice (18-22g) are placed into small cage leaving the tail exposed
 The proximal third of tail of the mice is placed on the radiant source .
 Time taken by the mice to w/d its tail is recorded.
 Tail-flick latency is recorded before & after 30, 60 & 120 minutes of administration
of standard & test compound.
• Evaluation
 The tail flick latency in the test, standard & control animals are compared.
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57. Tail flick model using immersion technique
The distal 5cm of tail is immersed in a cup filled with hot water at 55 C .
• The obvious difference is that the area of stimulation is far greater.
• It provokes an abrupt movement of tail& sometimes recoiling of whole body
• Reaction time is measured periodically before & after 15, 30,45 & 60 min in test as
well as standard drug group
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58. Hot plate method
• Rationale
 The paws of mice & rats are sensitive to heat, at temperatures which are
not damaging to skin.
 The responses are jumping & licking of the paws.
 The latency in responses is prolonged after administration of centrally
acting analgesics.
• Procedure
 Mice (18-22g) are used
 The temperature of the hot plate is maintained at 55° to 56°C.
 The animals are placed on the hot plate & time until either licking/ jumping
occurs is recorded.
 The latency is recorded before & after 20, 60 and 90 min after the
administration of standard & test compound.
• Evaluation
 The prolongation of latency time between the test, standard & control
animals are compared.
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59. Electrical stimulation of tail
• Electrical stimuli of gradually increasing intensities are applied in sequence
( lasting few milliseconds) through s/c electrodes places in tail of rat.
• When constant voltage of 40-50V is applied reflex movement of tail,
vocalization at the time of stimulation and continued beyond the time of
stimulation is observed.
• Morphine & morphine like drugs are effective in these models.
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60. Stimulation of the tooth pulp in rabbits
• Rabbit is anesthetized, pulp chambers are exposed using dental drill close to upper
incisors .
• Clamping electrodes are placed into the drilled holes
• After 30 min of accommodation, electrical stimulus is applied at 50Hz for 1 sec
starting with 0.2mA & increased until the animal starts licking.
• This response time increases after administration of analgesic.
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61. Haffner’s tail clip method
• Used for centrally acting analgesic agents.
• To the mice a noxious stimulus in form of artery clip is placed at root of tail
• Animal suddenly shows response in form of biting the clip/tail.
• Using a stop watch the reaction time between application of clip & response is
noted.
• Same procedure is repeated after 15, 30 & 60 min of drug administration.
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62. Acetic acid induced writhing
• Rationale
 When pain is induced by injecting 0.6% acetic acid into peritoneal cavity of mice, it
reacts with stereotyped behavior which is writhing.
 Characterized by stretching of the abdomen with simultaneous stretching of at
least 1 hind limb.
 The test is suitable to detect analgesic activity of peripherally acting drugs.
• Procedure
 Mice of either sex (20 - 25 g) is used
 Pain is induced by intraperitoneal injection of acetic acid that irritate serous
membranes
 The test and standard drug is administered 15 min prior to the acetic acid
administration.
 The writhing episodes were recorded for 30 mins .
• Evaluation
 The writhing period is recorded & compared with the standard group.
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63. FORMALIN TEST
• Chronic pain model.
• Pain is induced in Male Wistar rats (180–300 g) by a s/c injection of 0.05ml of
10% formalin on the dorsal surface of the right hind paw.
• Each individual rat is placed into a clear plastic cage for observation.
• The response is the amount of time the animals spend licking & biting of the
injected paw.
• Two distinct periods of high licking activity can be identified:
1.Early phase lasting the first 3-5 min
2.Late phase lasting from 15 to 30 min after the injection of formalin.
• Centrally acting analgesics(Morphine) are antinociceptive in both phases.
• NSAIDS(indomethacin and naproxen) inhibit only the late phase
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64. THANK YOU
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65. INVIVO SCREENING METHODS FOR
ANTI INFLAMMATORY AGENTS
Based on the symptoms observed during the inflammation invivo screening methods
for anti inflammatory drugs are characterized in to three phases:
 Acute/transient phase: ( vasodilation & increased capillary permeability)
 Sub acute phase : (Infiltration of leucocytes & phagocytes in blood. )
 Chronic inflammatory phase: (granuloma formation is observed in this phase.)
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66. ANIMAL MODELS
A.ACUTE PHASE
The methods that include acute phase are as follows:
 Carrageenan induced paw oedema in rats
 Histamine induced paw oedema in rats
 Arachidonic acid induced ear edema
 Croton-oil induced ear edema
 Oxazolone induced ear edema
 U V erythema in guinea pigs
 Vascular permeability
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67. B.SUBACUTR PHASE EXPERIMENTAL MODELS
 Carrageenan induced granuloma pouch model
 Formalin induced paw edema
C. CHRONIC PHASE
 Cotton pellet granuloma
 Glass rod granuloma
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68. CARRAGEENAN INDUCED PAW OEDEMA IN RATS
• Methodology :
 Male / female sprague-dawley rats weighing between 150 - 170g
 Starved for overnight .
 The animal are grouped into- test / standard drugs
 Drugs are administered one hour prior to the procedure.
 After 1hr, a subcutaneous injection of 0.05ml of 1% solution of carrageenan into
the plantar side of the left hind paw.
 The paw is marked with ink at the level of lateral malleolus and immersed in the
mercury up to this mark.
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69. • Evaluation:
 The paw volume was measured using plenthysmometer at 3 and 6 hr, eventually at
24 hr immediately after the injection.
 The increase in paw volume at 3 and 6 hr is calculated.
 % odema inhibition=[(Vc – Vt)/Vc]* 100 V-paw volume increase
 Generally the treated group animal show much less edema than control group
animal.
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70. CROTON-OIL INDUCED EAR EDEMA IN MICE
 In this methodology, administer varying dose of test compound to right ear of test
animal
 After 1 hour apply the acetonic solution croton-oil with a micropipette (15
muL/ear) to the inner surface of the right ear.
 Control animals receive only irritant.
 6 hours after croton oil application, the mouse is killed by cervical dislocation &
immediately remove both left & right ears.
 Degree of inflammation is measured.
 Difference in weight between the two ears is taken as the measure of edematous
response
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71. UV ERYTHEMA IN GUINEA PIGS
• Methodology:
 Albino guinea pigs of both the sexes weighing about 350g are used.
 Four animals are used each for test and the control.
 18hrs prior to the experiment, the animals are shaved on both the flanks and on the
back, chemically by means of a depilatory cream
 The next day the test compound is dissolved in the vehicle and half of it is
administered to the animal by gavage, 30min before the UV exposure.
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72.  Control animals are treated with the vehicle alone.
 The guinea pigs are placed in a leather cuff with a hole of 1.5x2.5cm size punched
in it, allowing the UV radiation to reach only this area.
 During this time, the remaining half of the test compound is administered.
 Generally the erythema is scored after 2 and 4 hr of exposure.
• Evaluation:
 The degree of erythema is evaluated in a double blinded manner. The following
scores are given:
0 – no erythema
1 – weak erythema
2 – strong erythema
4 – very strong erythema
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73. VASCULAR PERMEABILITY
Methodology:
 Albino Wistar are used –divided into groups, each group containing 4 rats.
 Control group will receive distilled water 1ml/100g by oral route and other group
will receive test compound by oral route and standard group will receive diclofenac
10ml/kg by intraperitoneal route.
 After 1hr of the administration, rats are injected with 0.25ml of 0.6% solution of
acetic acid intraperitoneally.
 Immediately, 10 ml/kg of 10% Evans blue is injected intravenously via tail vain.
 After 30 min, the animals are anesthetized with ether anesthesia and sacrificed.
 The abdomen is cut open and exposed viscera.
 The animals are held by a flap of abdominal wall over a Petri dish.
 The peritoneal fluid (exudates) collected, filtered and made up the volume to 10 ml
using normal saline solution and centrifuged at 3000 rpm for 15 min.
 The absorbance (A) of the supernatant is measured at 590 nm using
spectrophotometer.
Evaluation: Decreased concentration of dye with respect to absorbance indicates
reduction in permeability.
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74. COTTON WOOL INDUCED GRANULOMA
• Methodology:
 Male rats weighing about 180-200g are used.
 Two sterilized pellets of cotton wool were implanted subcutaneously, one on each
side of abdomen of the animal, under the light ether anaesthesia and sterile
technique.
 The test drugs were administered orally once on a dosage regimen for 7 days and
the control group received the vehicle.
 The rats were sacrificed on the 8th day, the implanted pellet was dissected out and
the wet weight was recorded.
 Both of these were dried at 60 celsius for 18 hrs and the dry weight was recorded.
• Evaluation: Average weight of the pellet of the control group as well as of the
test groups were calculated.
• % inhibition= [ (Wc-Wd)/Wc] * 100
Wc- difference in pellet weight of the control group
Wd- Difference in pellet weight of drug treated group
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75. questions
• Hit and run drugs-
• Drugs causing hyperuriceamia -
• Type of interation btw aspirin & mtx-Displacement
interationreaction.
• NSAID with immunosuppresant action-indomethacin
• Basic nsaid-nabumeton
• Common pk properties of nsaid
• WHY asthma & anaphylactoid reaction -
• Iv nsaid- Keterolac
• Advantage and dis adv of cox 2 inhibitors
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