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Adverse drug reactions


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ADVERSE DRUG REACTIONS Presented by:- Sonu M.Pharma Ist year RBIP, Mohali , Punjab

Adverse Drug Reactions (ADR):

Adverse Drug Reactions (ADR) Harm associated with the use of a given medications OR Unwanted or harmful reaction experienced after the administration of a drug or combination of drugs under normal conditions of use


Definition WHO defines an ADRs as, “any noxious and unintended effects of drug which occur at doses normally used in man foe the prophylaxis, diagnosis or therapy of disease or for the modification of physiological functions”

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ADR= significant morbidity & mortality Range from mild reactions (drowsiness, nausea, itching& rash); disappear after discontinuation of drug OR Severe reactions (respiratory depression, neutorpenia, hepatocellualr injury, hemorrhage, anaphylaxis

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ADR most common in Women Elderly (>60 yr old) Very young (1-4 y) Patients taking more than one drug

Classification of ADR:

Type-I (Augmented or Mechanism based adverse reaction) include side effects, toxic effects. Type-II (Bizzare) include hypersensitivity allergy and idiosyncrasy Type-III (Both Type-I and II or severe reactions) Classification of ADR

Classification of ADR:

Classification of ADR Rawlin & Thompson classification ABCD Traditional classification A & B About 80% of ADR----Type A reactions 1) Type A Reactions a) Related to pharmacological action of drug Extensions of the principal pharmacological action of the drug Cont.

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b) Predictable Relatively easily predicted by preclinical and clinical pharmacological studies c) Common Type A reactions not serious---common d) Dose-dependent Usually dose dependent

Type A reactions (classes) :

Type A reactions (classes) i) Toxicity of overdose (Drug overdose) An adverse drug reaction caused by excessive dosing e.g., hepatic failure with dose of paracetamol Headache with antihypertensives hypoglycemia with sulfonylurea;

ii) Side Effects:

ii) Side Effects Nearly unavoidable secondary drug effect produced by therapeutic doses intensity is dose dependent Occur immediately after initially taking drug or may not appear until weeks after initiation of drug use E.g., sedation with antihistamines

iii) Secondary Effects:

iii) Secondary Effects Secondary pharmacological effect E.g., development of diarrhea with antibiotic therapy due to altered GIT bacterial flora Orthostatic hypotension with a phenothiazine

iv) Drug Interactions:

iv) Drug Interactions When two drugs taken together & they effect each other’s response pharmacologically or kinetically E.g., one drug slow metabolism of 2 nd drug blood conc.= toxicity Theophylline toxicity in presence of erythromycin

2) Type B Reactions:

2) Type B Reactions Unrelated to known pharmacological actions of drug Unpredictable Often caused by immunological & pharmacogenetic mechanisms Unrelated to dosage Comparatively rare & cause serious illness or death cont.

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Results (more likely ) in withdrawal of marketing authorization Often not discovered until after drug is marketed Both environmental & genetic factors = important in this reaction

Type B Reactions (classes):

Type B Reactions (classes) i) Drug Intolerance Lower threshold to normal pharmacological action of a drug e.g., tinnitus (single average dose of aspirin) ii) Hypersensitivity (immunological reaction) Immune mediated response to a drug agent in sensitized patient e.g., anaphylaxis with penicillin

iii) Pseudoallergic Reaction:

iii) Pseudoallergic Reaction Direct mast cell activation & degranulation by drugs (opiates, vancomycin & radiocontrast media) Clinically indistinguishable form Type I hypersensitivity but not involve IgE (non immunologic reactions)

iv) Idiosyncratic Reactions :

iv) Idiosyncratic Reactions It is the term used to describe abnormal drug response. (Unexpected drug response) Characteristics of idiosyncracy are as follows: It occurs in genetically abnormal subjects. It arises only for few drugs. Prior drugs exposure is necessary. Its response is dose dependent. Its mechanism is explained by drug receptor interactions.

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An uncommon & abnormal response to drug Usually due to genetic abnormality Affect drug metabolism & receptor sensitivity Harmful even fatal, appear in low doses E.g., Anemia (hemolysis) by antioxidant drugs (G6PD deficiency) Paralysis due to succinylcholine (enzyme deficiency)

3) Type C (chronic) Reactions:

3) Type C (chronic) Reactions Associated with long-term drug therapy Well known and can be anticipated Adaptation occurs = discontinuation of drug=abstinence syndrome E.g. opoids, alcohol, barbiturates

4) Type D (delayed) Reactions:

4) Type D (delayed) Reactions Carcinogenic & teratogenic effects Delayed in onset Very rare Carcinogenic Effect Medication lead to cancer; take >20 y to develop Teratogenic Effect Drug- induced birth defects

Sign & Symptoms of ADR:

Sign & Symptoms of ADR Mild, moderate, severe or lethal Sign & symptoms manifest soon after 1 st dose or only after chronic use e.g., Allergic reactions occur soon after drug is taken usually 2 nd time ( itching, rash, eruption, upper or lower airway edema with dyspnea & hypotension) Idiosyncratic reactions =any unpredicted symptom

How to avoid Adverse effects::

How to avoid Adverse effects: ADRs can be minimised by: Decrease rate of parenterals administration. Decrease frequency of administration by use of prolonged action formulation. Adjusting tonicity to suit body fluids. Administering minimum effective dose for the shortest possible time. Monitoring closely the blood levels of toxic drugs particularly those which are hepatotoxic or nephrotoxic.

Mechanisms of ADR:

Mechanisms of ADR Type A =non immunological, reversible with reduction of dose, non serious, extension of pharmacological effects Type B Biochemical mechanism unrelated to pharmacological Immunologic = Hypersensitivity ( Type I, II, III, IV ) OR Non immunologic (direct)= Pseudoallergic, idiosyncratic, intolerance

Mechanism of Type B Reactions:

Mechanism of Type B Reactions i ) Often mediated by a chemically reactive metabolite Non detoxification of metabolite Direct cytotoxicity Direct tissue damage + necrosis

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ii) Bind to NA altered gene product Bind to a larger macromolecule inducing immune response (produce Ab & bind to Ab)

Drug Hypersensitivity (allergic) Reaction :

Drug Hypersensitivity (allergic) Reaction Common form of adverse response to drugs Classification (Gell & Coombs) Type I reactions (IgE-mediated) Type II reactions (cytotoxic) Type III reactions (immune complex) Type IV (delayed, cell mediated)

Examples of drugs which induces various diseases::

Examples of drugs which induces various diseases: Carcinogenic – e.g. Androgens, Estrogens and Oral contraceptives. Hepatotoxic – e.g. Amphetamine, Chloramphenicol, and PAS. Nephrotoxic – e.g. Corticosteroids, Aldosterone, Salicylates, Furosemide. Diabetogenics – e.g. Ascorbic acid derivatives, Nicotinic acid, Furosemide.

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GIT toxicity – e.g. Haematinics , Tricyclic anti-depressants. Dermatological toxicity – e.g. PAS, laxis , Nitrofurantoin . Diarrhoea – e.g. Antibiotics, digoxin , Neomycin. Pancreatitis – e.g. Cimetidine , Methyldopa.

Role of Pharmacist in Monitoring ADRs::

Role of Pharmacist in Monitoring ADRs: Pharmacist is involved in following steps of monitoring of ADRs: Literature review. Patient history. Drug level studies. Therapeutics decision making.

Any Query..? :

Any Query..?  Thank You…  

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