McKenna's Pharmacology, 2e

3

Toxic effects of drugs

Learning objectives Upon completion of this chapter, you should be able to: 1. Define the term adverse drug reaction and explain the clinical significance of this reaction. 2. List four types of allergic responses to drug therapy. 3. Discuss five common examples of drug-induced tissue damage. 4. Define the term poison. 5. Outline the important factors to consider when applying the clinical decision making process to selected situations of drug poisoning.

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Glossary of key terms blood dyscrasia: bone marrow depression caused by drug effects on the rapidly multiplying cells of the bone marrow; lower-than- normal levels of blood components can be seen dermatological reactions: skin reactions commonly seen as adverse effects of drugs; can range from simple rash to potentially fatal exfoliative dermatitis drug allergy: formation of antibodies to a drug or drug protein; causes an immune response when the person is next exposed to that drug hypersensitivity: excessive responsiveness to either the primary or the secondary effects of a drug; may be caused by a pathological condition or, in the absence of one, by a particular person’s individual response iatrogenesis/iatrogenic artifact: inadvertent adverse effects or complications caused by, or as a result of, medical treatment or advice poisoning: overdose of a drug that causes damage to multiple body systems and has the potential for fatal reactions stomatitis: inflammation of the mucous membranes related to drug effects; can lead to alterations in nutrition and dental problems superinfections: infections caused by the destruction of bacteria of the normal flora by certain drugs, which allow other bacteria to enter the body and cause infection; may occur during the course of antibiotic therapy

A ll drugs are potentially dangerous. Even though chemi­ cals are carefully screened and tested in animals and in people before they are released as drugs, drug products often cause unexpected or unacceptable reactions when they are administered. Drugs are chemicals, and the human body operates by a vast series of chemical reac­ tions. Consequently, many effects can be seen when just one chemical factor is altered. Today’s potent and amazing drugs can cause a great variety of reactions, many of which are more severe than those seen before.

ADVERSE EVENTS, ADVERSE DRUG EVENTS AND ADVERSE DRUG REACTIONS An adverse event (AE) is a drug-related harm in a person adminstered the drug but not necessarily caused by the drug. An adverse drug event (ADE) is harm that is caused by the use of a drug or inappropriate use of a drug while an adverse drug reaction (ADR) is harm directly caused by a drug at normal doses and is usually preventable.