Chapter 3
Adverse Reactions
Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc.
Adverse Reactions

Side Effects

Predictable
 Dose-related
 Acts on nontarget organs
 Examples include stomachache, headache,
nausea, vomiting, local effects
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Adverse Reactions

Toxic Reactions

Predictable
 Dose-related
 Acts on target organs
 Extension of the drug’s pharmacologic effects
 Examples include hypoglycemia with an oral
hypoglycemic agent or insulin
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Adverse Reactions

Allergic Reactions

Not predictable
 Not dose-related
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Adverse Reactions

Allergic Reactions

Type 1
• Mediated by immunoglobulin E (IgE) antibodies
• Anaphylactic shock or immediate hypersensitivity
reactions

Type 2
• Complement-dependent reactions involving IgG or
IgM antibodies
• Examples include penicillin-induced hemolytic
anemia
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Adverse Reactions

Allergic Reactions


Type III
• Mediated by IgG
• It is manifested as serum sickness
Type IV
• Delayed hypersensitivity reaction
• Mediated by T lymphocytes and macrophages
• Examples include allergic contact dermatitis
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Adverse Reactions

Idiosyncratic Reactions



This is a reaction that is neither a side effect or
an allergic reaction .
Some are genetically determined abnormal
reactions.
Some are due to an immunologic mechanism.
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Toxicologic Evaluation of Drugs

Therapeutic Index (TI = LD50)
ED50

An approximate statement of the relative safety of
the drug expressed as the ratio of the lethal or toxic
dose to the therapeutic dose of a drug
 LD50: Minimum dose causing death in 50% of a
sample population
 ED50: Dose required to produce a specified
intensity of effect in 50% of a sample population
Mosby items and derived items © 2007 by Mosby, Inc., an affiliate of Elsevier Inc.
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Drug Testing

Phase I Trials


Phase II Trials


The main purpose of this phase is to test for drug
effectiveness and adverse effects
Phase III Trials


Determines the biologic effects, safe dose range in
humans, and toxic effects of the drug
Patients with the actual drug indication receive the drug.
The drug is evaluated for safety and efficacy
Phase IV Trials

Postmarketing surveillance
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