DHE122 Chapter#3

  1. Adverse Reactions of drugs:
    • Drugs may act on biologic systems to accomplish a desired effect, but they lack absolute specificity
    •    They can act on many different organs or tissues
    •    This is the reason for undesirable or adverse drug reactions
    • No drug is free from producing some adverse effects in a certain number of patients
  2. Therapeutic effects
    are clinically desirable actions
  3. Adverse effects
    are clinically undesirable reactionsNot desired, potentially harmful, and occurs at usual therapeutic doses
  4. Toxic reaction:
    • an extension of the pharmacologic effect resulting from a drug’s effect on the target organs
    • The amount of the desired effect is excessive
  5. Side effect:
    • a dose-related reaction that is not part of the desired therapeutic outcome
    • Drowsiness related to antihistamine use
  6. Idiosyncratic reaction:
    a genetically related abnormal drug response
  7. Drug allergy:
    • hypersensitive response following previously exposure to drug. not dose related
    • Neither predictable nor dose related
    • Interferes with natural defense mechanisms
    •    The drug reduces body’s ability to fight infection
  8. Exaggerated Effect on Target Tissues:
    • An extension of therapeutic effect caused by the overreaction of a sensitive patient or by a dose that is too large for that patient.
    • Occasionally, this may result from liver or kidney disease
  9. Effect on Nontarget Tissues:
    • Nontherapeutic action of the drug:Reactions can occur at usual doses
    • Appear more often at higher doses
    • A reduction in dose = reduction in adverse reactions
  10. Effect on Fetal Development (Teratogenic Effect)
    • The relationship between drugs and congenital abnormalities has been recognized since the middle of the twentieth century
    • “Although more information is now available about the safety of drugs in pregnant women, sufficient information is still lacking”
    • The U.S. Food and Drug Administration (FDA) has attempted to address concerns about the lack of adequate knowledge of drugs by defining five FDA pregnancy categories
    • They are A, B, C, D, and X (from least to most risky)
  11. Local effect- local reactions
    • characterized by local tissue irritation
    • Injectable drugs produce irritation, pain, and tissue necrosis at the site of injection
    • Topically agents produce irritation at the site of application
    • PO drugs can produce gastrointestinal upset such as nausea
  12. Drug Interactions can occur when?
    • A drug interaction can occur when the effect of one drug is altered by another drug:
    • Interactions may result in
    • Toxicity
    • Lack of efficacy
    • or produce beneficial effects
    • The more often the drug is taken the more likely drug interactions occur.
  13. Hypersensitivity (Allergic Reaction)
    • Occurs when the immune system of an individual responds to the drug administered or applied
    • The drug must act as an antigen, stimulates antibody production in a previously sensitized patient
    • Neither dose dependent nor predictable
    • Drug allergy can be divided into four types of reactions, depending on the type of antibody produced or the cell mediating the reaction
  14. Type I (Immediate)
    • Mediated by immunoglobulin E (IgE) antibodies
    • When a drug antigen binds to IgE antibody, histamine, leukotriene, and prostaglandins are released, producing vasodilation, edema, and inflammation
    • The targets of this reaction are
    • Bronchioles, resulting in anaphylactic shock
    • Respiratory system, resulting in rhinitis and asthma
    • Skin, resulting in urticaria and dermatitis
    • Because these reactions can occur quickly after drug exposure, they are known as immediate hypersensitivity reactionsAnaphylaxis is an acute, life-threatening allergic reaction characterized by hypotension, bronchospasm, laryngeal edema, and cardiac arrhythmias
  15. Type II (Cytotoxic/Cytolytic)
    • Complement-dependent reactions involving either immunoglobulin G (IgG) or immunoglobulin M (IgM) antibodies
    • The antigen-antibody complex is fixed to a circulating red blood cell, resulting in lysis
    • Examples are penicillin-induced hemolytic anemia and methyldopa-induced autoimmune hemolytic anemia
  16. Type III (Arthus reactions)
    • Mediated by IgG antibodies
    • The drug antigen-antibody complex fixes complement and deposits in the vascular endothelium
    • Manifested as serum sickness; includes urticarial skin eruptions, arthralgia – joint pain, arthritis, lymphadenopathy, and fever
    • Can be caused by penicillins and sulfonamides
  17. Type IV (Delayed Hypersensitivity)
    • Mediated by sensitized T lymphocytes and macrophages
    • When the cells contact the antigen, an inflammatory reaction is produced by lymphokines, neutrophils, and macrophages
    • An example is contact dermatitis caused by topical application of drugs
  18. Interference with Natural Defense Mechanisms
    • A drug’s effect on the body’s defense mechanisms can result in an adverse reaction
    • Long-term administration of corticosteroids results in decreased resistance to infection
  19. Toxicologic Evaluation of Drugs
    • Evaluations of the toxic effects of drugs are based on experiments performed with lower animals and clinical trials conducted in humans
    • Animal experiments can often elicit adverse reactions that could occur in humans, but drug reactions in animals do not always predict reactions in humans
  20. LD50
    is the dose the kills 50% of experimental animals
  21. ED50
    is the dose required to produce a specified intensity of effect in 50% of the animals
  22. The ratio LD50/ED50
    is the therapeutic index (TI) of a drug
  23. If TI is small (narrow TI),
    then toxicity is more likely
  24. If TI is large (wide TI),
    then the drug will be safer
  25. A TI of greater than 10 is usually needed to produce a
    therapeutically useful drug
  26. Agonist –
  27. Antagonist –
  28. Receptor –
    molecule that plays role in regulatory system
  29. Chemical antagonists –
    drugs that interact with other drugs
  30. Hormones –
    drugs synthesized in the body
  31. Sympathetic neurons include –
    norepinephrine and epinephrine
  32. Adrenal glands release
  33. _____ the neurotransmitter released in acetylcholine.  In order for the nerve to quit synapsing ______ is released and the nerve quits contracting.
    • Parasympathetic
    • acetylcholinesterase
  34. Autonomic Nervous System (ANS) is a —Body system that is made up of two divisions?
    • ◦Parasympathetic autonomic nervous system (PANS)
    • ◦Sympathetic autonomic nervous system (SANS)
  35. ANS drugs used in dentistry such as:
    ◦Vasoconstrictors and drugs used to increase salivary flow
  36. —Some ANS drugs produce oral adverse reactions -
    ◦Anticholinergics produce xerostomia
  37. Autonomic Nervous System (ANS)is in charge of ______
    many of the body systems i.e regulation of blood pressure, heart rate, gastrointestinal (GI) tract motility, salivary gland secretions, and bronchial smooth muscle
  38. The ANS relies on specific neurotransmitters and receptors to initiate communication between ______
    neuron and target tissues
  39. Each division of the ANS has
    afferent (sensory) fibers, central integrating areas, and efferent motor preganglionic and postganglionic fibers
  40. Neurotransmitters:
    Between postganglionic nerves and effector tissues
  41. PANS: the neurotransmitter released from the preganglionic nerve is?
  42. PANS: the neurotransmitter released from the postganglionic nerve is?
    • acetylcholine
    • It is also termed cholinergic
    • Because the postsynaptic tissue responds to muscarine, it is called muscarinic
  43. In the (SANS)sympathetic division, the preganglionic neuron releases?
    ACh acetylcholine
  44. SANS: What transmitter substance is released by the postganglionic nerve ?
    • ( NE) norepinephrine
    • adrenergic
Card Set
DHE122 Chapter#3
DHE122 Chapter#3