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Non-steroidal Anti-inflammatory Drugs

Non-steroidal Anti-inflammatory Drugs. Dr.B.V.Venkataraman Professor in Pharmacology International Medical School Faculti Perubatan, New BEL Rd Bangalore - 560054 Venkataraman_bv@yahoo.com. COX. Physiological stimulus Inflammatory stimulus. Macrophages/other cells. COX-1 Constitutive.

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Non-steroidal Anti-inflammatory Drugs

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  1. Non-steroidal Anti-inflammatory Drugs Dr.B.V.Venkataraman Professor in Pharmacology International Medical School Faculti Perubatan, New BEL Rd Bangalore - 560054 Venkataraman_bv@yahoo.com

  2. COX

  3. Physiological stimulusInflammatory stimulus Macrophages/other cells COX-1 Constitutive Cox-2 Induced Other inflammatory mediators Proteases PGs TXA2 Platelets PGI2, endothelium Stomach mucosa etc PGE2, Kidney etc INFLAMMATION

  4. Classification of NSAID COX-1 and COX-2 inhibitors • Salicylates: Aspirin • Para-aminophenols: Phenacetin, Paracetamol. • Pyrazolons: Phenylbutazone • Indoles: Indomethacin, Sulindac, Tolmetin, Ketorolac. • Phenylacetates: Diclofenac • Propionates: Ibuprofen, Ketoprofen, • Fenamates: Flufenamic acid and Mefenamic acid. • Oxicams: Piroxicam

  5. Classification of NSADs (contd) • COX-2 inhibitors (Coxibs) Valdecoxib, etorocoxib • COX-3 inhibitors Paracetamol • Miscellaneous COX Inhibitors Nimesulide, Meloxicam, Etodolac etc • Drugs do not inhibit PGs Nefopam

  6. SALYCILATES • Source: bark of willow (used in malaria) • Now it is commercially synthesised. • Salicylic acid • Sodium salicylate • Acetyl salicylic acid (aspirin) • Methyl salicylic acid (oil of winter green) • Diflunisal is a derivative of aspirin.

  7. SALICYLATES LOCAL ACTIONS • Irritants • Salicylic acid: Keratolytic, used in ring worm infection • Methyl salicylate: counter irritant in relieving joints and muscular pain

  8. Aspirin: systemic effects • Analgesic Aspirin

  9. Types of Analgesis Two types • Narcotic analgesics Relieve pain and produce sedative/hypnotic effect e.g. morlphine, pethidine 2. Non-narcotic analgesics Relieve pain with out affecting the consciousness e.g. aspirin, paracetamol

  10. Systemic actions of aspirin • Antipyretic action: Inhibition of central PG • Antiplatelet action:

  11. (Anti inflammatory action)

  12. Systemic actions of aspirin • TxA2 is present in platelets • At any dose anti-platelet aggregation (inhibiting TXA2) • At low dose PGI2 not inhibited • At high dose PGI2 is inhibited. • PGI2 : vasodilator and anti-platelet aggregation. • Action is irreversible. • Duration 8-10 days (life of platelet)

  13. Systemic actions of Salicylates • Renal effect: PGE2 (vasodilator) coordinate with angiotensin-II. Chronic NSAIDs leads to inhibition of PGE2 and vasoconstriction. • Respiration: directly and indirectly. O2 leads to CO2 which stimulates respiratory centre. These events leads to hyper ventilation. • Low dose decrease the uric acid level. High dose uricosuric effect.

  14. Pharmacokinetics • Well absorbed from stomach and small intestine • Empty stomach and acid medium helps absorption • Deacetylation in gut wall, liver, plasma & other tissues after absorption. • Protein binding 80% • Conjugated with glycine. • 1/10 is excreted in active form which can be enhanced with alkalinisation.

  15. Side effects of aspirin • Intolerance (rare): rashes, urticaria, asthma etc. • Gastric irritation • Hypoprothrombinemia: Vit K is antidote • Reye’s syndrome: Children prescribed for viral fever. Syndrome consists of liver dysfunction (fatal) • Salicylism: headache, dizziness, vertigo, difficulty in hearing and dimness of vision. The symptoms are reversible once the drug is withdrawn.

  16. Treatment of acute salicylate poisoning • Symptomatic treatment • Patent airway • Hyperthermia: reduced by external cooling. • Dehydration should be corrected. • Vitamin K should be administered. • Metabolic acidosis is corrected by NaHCO3 which also promotes renal excretion of salicylates. • Forced diuresis is done by administration of furosemide (40 mg) in the infusion fluid. • Dialysis is done in renal failure.

  17. Clinical uses of Salicylates • Keratolytic and antifungal : salicylic acid • Counter irritant: Methyl salicylic acid • Acute rheumatic fever: Streptococcal infection induces antibodies reacting with lymphocytes. These antibodies react with heart valves and myocardium. Treatment: a. Penicillin for the streptococcal infection. b. Aspirin (5-8 g in divided doses) for the inflammation. c.corticosteroids can also be given.

  18. Clinical uses of aspirin • Arthritis and fibromyositis: In rheumatoid arthritis, aspirin at 5-6 g in divided doses is advised. • Ischaemic heart disease: In low doses (100 mg daily) aspirin is given to prevent platelet aggregation. • Pain: headache, fever, dysmenorrhoea etc. • For closure of patent ductus arteriosus.

  19. Drug interaction • Aspirin displaces oral anticoagulants, oral antidiabetics etc. • Interfers with uric acid excretion (analgesic dose inhibit) • Decreases the diuretic actions (thiazides and furosemide) • Reduces the K+ sparing action of spiranolactone.

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