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Adverse drug reaction 2.pptx

  1. ADVERSE DRUG REACTIONS: A response to a drug which is noxious & Unintended & which occurs at normal doses used in man. ADVERSE DRUG EVENTS: Any untoward medical occurance that may present during treatment with a pharmaceutical product(drug),but which does not necessarily have a causal relationship with this treatment.
  2. ⦁ WHO defined it as the “science & activities related to the detection, assessment, understanding & prevention of adverse effects or any other drug related problems.” ⦁ The information generated by pharmacovigilance is useful in educating doctors about ADRs & in the official regulation of drug use. ⦁ It has important role in rational use of medicines & assessing safety of medicines.
  3. ADRs can be minimised but not eliminated by observing the following practices:  Avoid all inappropriate use of drugs in the context of patient’s clinical condition.  Use correct dose,route & frequency of drug administration based on patient’s specific variables.  Take into consideration about previous history of drug reactions,allergic diseases &exercise caution(drug allergy is more common in allergic patients)
  4.  Rule out possibility of drug interactions when more than one drug is prescribed.  Adopt correct drug administration technique (eg:iv inj of vancomycin must be slow).  Carry out appropriate laboratory monitoring (serum drug levels with lithium). SEVERITY OF ADVERSE DRUG REACTIONS: Minor:No therapy,antidode or prolongation of hospitalization is required. Moderate:Requires change in drug therapy,specific treatment or prolongs hospital stay atleast one day. Severe:Potentially life threatening,causes permanent damage/requires intensive medical treatment. Lethal:Directly/indirectly contributes to death of the patient.
  5. Adverse drug effects may be categorized into: 1).Side effects: Unwanted & unavoidable p’dynamic effects occurs at therapeutic doses.  Reduction of dose generally ameliorates the symptoms.  Side effects may be based on same action as the therapeutic effect. eg; Atropine is used as preanaesthetic for its antisecretory action,the same action produces dryness of mouth as side effect.  Many drugs have been developed from observation of side effects. eg; sulfonamides (antibacterial) used as hypoglycemic sulfonylureas.
  6. ⦁ These are indirect consequences of a primary action of drug. Eg;corticosteroids weekens host defence mechanisms so that latent TB gets activated. 3).Toxic effects: ⦁ Due to excessive p’cological action of the drug due to overdose & prolonged use. ⦁ The effects are predictable & dose related. ⦁ They result from functional alteration(high dose of ATROPINE causes DELIRIUM)or drug induced tissue damage(Hepatic necrosis from PARACETAMOL overdose).
  7. Poisoning: ⦁ Due to large doses of drugs. ⦁ Poison endangers life by severely affecting one or more vital functions. MEASURES:  Resuscitation & maintenance of vital functions: Adequate ventilation,artificial respiration, maintenance of BP, heart beat, body temperature & blood sugar level.  Termination of exposure: Removing patient to fresh air,washing skin & eyes,induction of emesis with syrup ipecac/gastric lavage [avoided in kerosine & CNS poisoning]
  8.  Prevention of absorption of ingested poisons:  20-40g(1g/kg) of activated charcoal suspension should be administered in 200ml of water. Strong acids& alkalies,metallic salts,iodine, cyanides,alcohol,organic solvents are not adsorbed by charcoal.  Hastening elimination: Quick removal of poison from the body by haemodialysis,inducing diuresis/altering urinary pH.
  9. 4).Intolerance: known as inability to withstand/consume the drug. Eg; only few doses of carbamazepine may cause ataxia in some people. 5).Idiosyncrasy: It is genitically determined abnormal reactivity to a chemical. Peculiar to an individual because the drug reacts with the specific gene which is specific to an individual. Eg; Barbiturates causes excitement & mental confusion in some individuals.
  10. 6).Drug allergy: ⦁ A medical condition that makes a individual to feel ill when a drug is taken. ⦁ Allergic reactions occur only in a small proportion of the population exposed to the drug & cannot be produced in other individuals. ⦁ Occur even with smaller doses & have a different time course of onset & duration,also called as HYPERSENSITIVITY but not supersensitivity. ⦁ The drug/its metabolites acts as AG/HAPTEN & induce production of AB/sensitized lymphocytes. ⦁ They are of two types: HUMORAL & CELLMEDIATED.
  11. A. HUMORAL:  TYPE-I(anaphylactic)REACTIONS: On exposure to the drug,AG:AB reaction takes place on the mast cell surface releasing mediators like histamine,5HT,leukotrienes Prostaglandins etc.,resulting in itching, angioedema, bronchospasm, rhinitis.  TYPE-II(cytolytic)REACTIONS: Drug+component of a specific tissue cells act as AG.The resulting antibodies(IgG,IgM)bind to the target cells on reexposure AG:AB reaction takes place on the surface of these cells,complement is activated and cytolysis occurs.
  12.  TYPE-III(retarded)REACTIONS: AG:AB complexes bind complement & precipitate on vascular endothelium giving rise to a destructive inflammatory response. Manifestations are rashes, serum sickness, mental symptoms, myocarditis, nephritis(usually in 1-2weeks) B.CELL MEDIATED:  TYPE-IV(delayed hypersensitivity)REACTIONS: These are mediated through production of sensitized T- lymphocytes carrying receptors for the AG.They form inflammatory response. Eg:dermatitis,rashes,fever,photosensitization takes>12hrs to develop.
  13. TREATMENT:  Administration of oxygen.  0.5mg adrenaline i.m injection.  Administer a H1 antihistaminic i.m/slow i.v.  I.V of glucocorticoids should be added in many cases.  Adrenaline followed by a short course of glucocorticoids is indicated for bronchospasm attending drug hypersensitivity.  Glucocorticoids are the only drug in type II,III,IV reactions.
  14. 7).Photosensitivity: It is a cutaneous reaction resulting from drug induced sensitization of the skin to Uvrays.the reactions are of two types: a) Phototoxic: Drugs/its metabolites accumulates in the skin,absorbs light & undergoes a photochemical reaction followed by a photobiological reaction resulting in local tissue damage.[edema,blistering etc drugs involved are tetracyclines,thiazides] b) Photoallergic: Rarely AB mediate photoallergy & the reaction takes form of flare&wheal on exposure to sun drugs involved are sulfonamides,chloroquines etc.
  15. 8).Drug dependence: It is a state in which use of drugs for personal satisfaction is accorded a higher priority than other basic needs,often in the face of known risks to health. a].Psychological dependance:individual believes optimal state of wellbeing is achieved only through the actions of the drugs[cocaine,opioids,BZPs]. b].Physical dependance:an altered physiological state produced by repeated administration of a drug which necessitates the continued presence of the drug to maintain physiological equilibrium.  Discontinuation of the drug leads to withdrawl syndrome.[BZDs,alcohol,cocaine].
  16. c].Drug abuse:social disapproval of the manner & purpose of drug use. d].Drug addiction:strong physiological & psycological dependence on a drug. Eg;Narcotics,cocaine,Amphetamines. e].Drug habituation:a psychological dependence on drug due to repeated consumption with a desire to continue its use,withdrawal produces only mild discomfort. Eg:coffee,tea,social drinking.
  17. 9).Drug withdrawal reactions: These reactions are produced when there is sudden cessation of the drug or interruption of therapy with certain other drugs. Eg;precipitation of MI may result from stoppage of beta blockers. 10).Teratogenicity: It refers to capacity of a drug to cause foetal abnormalities when administered to the pregnant mother. Eg; Warfarindepressed nose,growth retardation.
  18. 11).Mutagenicity & Carcinogenicity: The capacity of a drug to cause genitic defects &cancer respectively. Usually oxidation of the drug results in the production of reactive intermediates which effects genes & may cause structural changes in the chromosomes. Eg; anticancer drugs, tobacco, estrogens, radioisotopes. 12).Drug induced diseases: These are iatrogenic(physician induced)diseases & functional distrubances(disease)caused by drugs which persists even after the offending drug has been withdrawn & largely eliminated. eg:peptic ulcer by salicylates & corticosteroids.
  19. References    Essentials of Medical pharmacology by K.D Tripathi pg;no :78-86