Adverse Reactions Chapter 3 PDF

Adverse Reactions Chapter 3 Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 1  Drugs  Accomplish desired effects  Lack absolute specificity  Create undesirable or adverse drug reactions...

Adverse Reactions Chapter 3 Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 1  Drugs  Accomplish desired effects  Lack absolute specificity  Create undesirable or adverse drug reactions Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 2  More than One Action  Therapeutic effects: desirable actions  Adverse effects: undesirable reactions  Could the adverse effect be a therapeutic effect? Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 3  Adverse Drug Reactions  Response to a drug that is not desired, potentially harmful, and occurs at usual therapeutic doses Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 4  Categories of Adverse Drug Reactions  Toxic reaction  Side effect  Drug Allergy  Idiosyncratic reaction  Interference with natural defense mechanisms  Teratogenic Effects  Local Effects  Drug Interactions Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 5  Toxic Reaction  Extension of the pharmacological effect; dose related; exaggerated response on target tissues  Ex. Patient given therapeutic dose of oral hypoglycemic agent for diabetes; blood sugar falls too low Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 6  Side effect  Not part of the desired therapeutic action; dose related; drug acts on non-target tissues to produce undesirable effects  Ex. ibuprofen given for pain and causes an upset stomach Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 7  Drug Allergy  Hypersensitivity response to a drug to which the patient was previously exposed; NOT dose related or predictable  Acts as an antigen (hapten) and reacts with an antibody in a previously sensitized patient  Less than 5% of all adverse reactions  4 types of reactions (ABCD) Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 8  Type I Drug Allergy (Occurs within minutes)  Anaphylactic shock – acute life threatening  Rhinitis  Asthma  Urticaria  Dermatitis  Hypotension  Bronchospasm  Laryngeal edema  Cardiac arrhythmias  Local anesthetics and penicillins Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 9  Type II: Cytotoxic/Cytolytic Drug Reaction (occurs hours to days later)  Antigen/Antibody complex is fixed to a circulating blood cell causing cell death  Ex. Bad Blood penicillin-induced hemolytic anemia Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 10  Type III: Immune Complex, Arthus, Serum Sickness (2-3 weeks later)  Clumps of antigen-antibody complexes deposit in the vascular endothelium  Manifested as: Serum sickness Urticarial skin eruptions Arthralgia Arthritis Lymphadenopathy Fever Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 11  Type IV: Delayed Hypersensitivity (2-3 days later)  Reactions are mediated by sensitized T lymphocytes and macrophages; antibodies not responsible  Ex. Poison oak, cheap jewelry, autoimmune disease  ABCD Reactions Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 12  Idiosyncratic Reaction  A reaction that is neither the drug’s side effect nor an allergic reaction; genetically related Abnormal reaction Immunological issue  Example: Eskimos metabolize certain drugs faster than others therefore larger dose may be needed. Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 13  Interference with Natural Defense Mechanisms  A drug’s effect on the body’s defense mechanisms can result in an adverse reaction  Long term use of corticosteroids can lead to decreased resistance to infection. Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 14  Teratogenic Effect  terato- = monster  -genic = producing  Teratogens are agents that cause congenital malformations and developmental abnormalities if introduced during gestation  Table 22.1 page 250 Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 15  Teratogenic Effect  NO drug can be  Drugs contraindicated considered “safe” during pregnancy  Safest drugs to use tetracycline during pregnancy Nonsteroidal penicillin antiinflammatory erythromycin agents acetaminophen* benzodiazepines Local anesthetic metronidazole lidocaine thalidomine Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 16  Local Effect  Local reactions are characterized by local tissue irritation  Injectable drugs can produce irritation, pain, and tissue necrosis at the site of injection  Topically applied agents can produce irritation at the site of application  Drugs taken orally can produce gastrointestinal symptoms such as nausea or dyspepsia Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 17  Drug Interactions  The effect of one drug is altered by another drug Drug-drug Drug-food Drug-disease  Table 3-1 page 26 Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 18  Toxicological Evaluation of Drugs  Evaluations of the toxic effects of drugs are based on experiments performed on animals and clinical trials conducted in humans  Lethal dose: Dose of drug that kills 50% of the experimental animals  Median effective dose: Dose required to produce a specified intensity of effect in 50% of the animals Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 19 Toxicological Evaluation of Drugs (Cont.) Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 20 Toxicological Evaluation of Drugs (Cont.) Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 21  Recognizing Adverse Effects  Patient education  Communication Determine drugs patient is taking Determine when patient is taking each drug Determine if symptoms occurred after beginning drug therapy Determine how long after beginning drug therapy that symptoms began Identify drug causing adverse effect Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 22  Dental Hygiene Considerations  Know the difference between side effect, toxic effect, and allergic reaction  Ask patient for more information  Allergic to one drug = allergic to drugs in same chemical class  Educate patients about possible adverse drug effects and what should be done if they occur  Ask if patient may be pregnant Copyright © 2016 by Mosby, Inc., an imprint of Elsevier Inc. All rights reserved. 23