Introduction to Nursing Pharmacology Nursing Pharmacology

Toxic Effects of Drugs

Toxic Effects of Drugs

Adverse Drug Reaction

  • Definition
    • Adverse effects are undesired effects that may be unpleasant or even dangerous
  • Reasons adverse drug reactions occur:
    • The drug may have other effects on the body besides the therapeutic effect
    • The patient is sensitive to the drug given
    • The drug’s action on the body causes other responses
    • The patient is taking too much or too little of the drug

Types of Adverse Reactions

  • Primary actions
    • Overdose: extension of the desired effect
  • Secondary actions
    • Undesired effects produced in addition to the pharmacologic effect
  • Hypersensitivity reactions
    • Excessive response to the primary or secondary effect of the drug

Types of Drug Allergies

  • Anaphylactic reaction
  • Cytotoxic reaction
  • Serum sickness reaction
  • Delayed allergic reaction

Variety of Adverse Effects Associated With Drug Use

Types of Drugs Allergies
Types of Drugs Allergies

Drug-Induced Tissue & Organ Damage

Drug-Induced Tissue and Organ Damage
Drug-Induced Tissue and Organ Damage

Dermatologic Reactions

  • Rash/hives
    • Assessment
      • Abnormalities in the skin, red areas, blisters
    • Interventions
      • May need to discontinue the medication
  • Stomatitis
    • Assessment
      • Inflammation of the mucous membranes
    • Interventions
      • Frequent mouth care

Drug-Induced Tissue and Organ Damage

  • Superinfections: destruction of the body’s normal flora
    • Assessment
      • Fever, diarrhea, and vaginal discharge
    • Interventions
      • Supportive care (mouth/skin care), give antifungal medications, stop drug responsible for the infection
  • Blood dyscrasia: bone marrow suppression
    • Assessment
      • Fever, chills, and weakness
    • Interventions
      • Monitor blood counts and protective isolation


  • Liver
    • Assessment
      • Fever, nausea, jaundice, change in color of urine or stool, and elevated liver enzymes
    • Interventions
      • Discontinue medication
  • Kidney
    • Assessment
      • Change in urinary pattern or elevated BUN and creatinine
    • Interventions
      • Notify physician, stop medication, or decrease dosage


  • Poisoning occurs when an overdose of a drug damages multiple body systems
  • Damage to multiple systems can lead to a fatal reaction

Altered Glucose Metabolism

  • Hypoglycemia
    • Assessment finding: low serum blood glucose level
    • Intervention: restore glucose to the body (D50)
  • Hyperglycemia
    • Assessment finding: high serum glucose level
    • Intervention: administer medications to decrease glucose level (insulin)

Electrolyte Imbalances

  • Hypokalemia
    • Assessment finding: decrease in serum potassium level
    • Interventions: replace serum potassium (IV or oral supplement) and monitor serum level of potassium
  • Hyperkalemia
    • Assessment finding: increase in serum potassium level
    • Interventions: decrease the serum potassium concentration (using sodium polystyrene sulfonate), monitor serum level of potassium, and monitor cardiac rhythm

Sensory Effects

  • Ocular toxicity
    • Assessment finding: visual changes
    • Interventions: monitor for visual changes when giving medication known to cause ocular damage; discontinue medication after notifying physician
  • Auditory damage
    • Assessment finding: damage to the eighth cranial nerve
    • Interventions: monitor for hearing loss; discontinue medication after notifying physician

Neurologic Effects

  • General central nervous system (CNS) effects
    • Assessment: altered level of consciousness
    • Intervention: prevent injury
  • Atropine-like (anticholinergic) effects
    • Assessment: dry mouth, urinary retention, and blurred vision
    • Interventions: sugarless lozenges to keep mouth moist; advise the patient to void before administration of the medication
  • Parkinson-like syndrome
    • Assessment: muscle tremors and changes in gait
    • Intervention: discontinue medication
  • Neuroleptic malignant syndrome
    • Assessment: extrapyramidal symptoms
    • Intervention: discontinue medication


  • Drugs may harm the developing fetus or embryo
  • Prevent teratogenicity through teaching
    • Advise pregnant women that any medication may adversely affect the baby
    • Weigh the actual benefits against the potential risks
    • Advise pregnant women that they should not take medications without checking with their health care provider first
Introduction to Nursing Pharmacology Nursing Pharmacology

Drugs and The Body

Drugs and the Body


  • Pharmacodynamics is the science of dealing with interactions between living organisms and foreign chemicals
  • Chemical reactions occur continuously in the body of each living system
  • When other chemicals (drugs) are added to the body, additional effects occur

Drug Actions

  • To replace or act as substitutes for missing chemicals
  • To increase or stimulate certain cellular activities
  • To depress or slow certain cellular activities
  • To interfere with the functioning of foreign cells

Receptor Cells

  • Receptor site reacts to certain chemicals
  • The better the fit between receptor site and chemical, the more pronounced the reaction
  • Enzymes within the body are needed to break down the chemicals to open up the receptor site

Lock & Key

Drugs and The Body: Lock and Key
Drugs and The Body: Lock and Key


  • Drugs can interfere with the enzymes that may be catalysts for chemical reactions
  • Enzymes produce a cascade effect


  • Onset of drug action
  • Drug half-life
  • Timing of the peak effect
  • Duration of drug effects
  • Metabolism or biotransformation of the drug
  • Site of excretion

The Processes by Which Drugs Are Handled in the Body

The Processes by Which Drugs Are Handled in the Body
The Processes by Which Drugs Are Handled in the Body


  • Critical concentration
    • The amount of a drug that is needed to cause a therapeutic effect
  • Loading dose
    • A higher dose than that usually used for treatment
  • Dynamic equilibrium
    • The actual concentration that a drug reaches in the body

Dynamic Equilibrium

  • The actual amount of drug that reaches the body results in a dynamic equilibrium
  • Dynamic equilibrium is affected by:
    • Absorption
    • Distribution
    • Biotransformation
    • Excretion


  • Administration
    • Affected by route of administration
    • Oral medications affected by presence of food in the stomach
  • First-pass effect
    • Medications are extensively metabolized by the liver

Factors Affecting Absorption

Factors That Affect Absorption of Drugs
Factors That Affect Absorption of Drugs


  • Protein binding
  • Blood–brain barrier
  • Placenta/breast milk


  • The liver is the single most important site for biotransformation (metabolism)
  • This process breaks down medications
  • It helps to prevent medications from causing adverse effects on the body


  • Removal of drugs from the body
  • Kidneys play the most important role in the excretion of medication


  • Half-life is the time it takes for the amount of drug in the body to decrease to one-half the peak level
  • Half-life is affected by the absorption, distribution, metabolism, and excretion





Calculating Half-Life

Focus on Calculations
Focus on Calculations

Factors Influencing Drug Effects

  • Weight
  • Age
  • Gender
  • Physiologic factors
  • Pathologic factors
  • Genetic factors
  • Immunologic factors
  • Psychological factors
  • Environmental factors
  • Drug tolerance
  • Cumulative effect

Drug-to-Drug Interactions

  • Can occur any time two or more drugs are taken together
  • Can occur at:
    • Site of absorption
    • During distribution
    • During biotransformation
    • During excretion
    • At the site of action

Drug–Food Interaction

  • Certain foods interact with drugs
  • Drugs are best taken on an empty stomach

Drug–Laboratory Test Interaction

  • Drugs may alter the results of lab testing
  • Laboratory tests may be used to monitor the effects of other medications