Categories
Introduction to Nursing Pharmacology Nursing Pharmacology

Drugs and The Body

Drugs and the Body

Pharmacodynamics

  • 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

Enzymes

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

Pharmacokinetics

  • 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

Pharmacokinetics

  • 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

Absorption

  • 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

Distribution

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

Biotransformation

  • 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

Excretion

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

Half-Life

  • 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

Pharmacokinetics

Pharmacokinetics
Pharmacokinetics

Half-life

Half-Life
Half-Life

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
Categories
Introduction to Nursing Pharmacology Nursing Pharmacology

Introduction to Drugs

Nurses’ Responsibility

  • Administering drug
  • Assessing for adverse drug effects
  • Intervening to make the drug regimen more tolerable
  • Providing patient teaching about drugs and the drug regimen
  • Monitoring and prevention of medication errors

Pharmacology

  • Pharmacology is the study of the biological effects of chemicals
  • Health care providers focus on how chemicals act on living organisms

Pharmacotherapeutics

  • A branch of pharmacology that uses drugs to treat, prevent, and diagnose disease
  • Pharmacotherapeutics focuses on:
    • The drug’s effect on the body
    • The body’s response to the drugs
  • Drug effects
    • Therapeutic
    • Adverse

Sources of Drugs

  • Plants
  • Animal products
  • Inorganic compounds
  • Synthetic sources

Plants

Focus on Drugs Derived From Plants
Focus on Drugs Derived From Plants

Animal Products

  • Animal products are used to replace human chemicals
  • Used less frequently due to genetic engineering
  • Synthetic preparations are considered safer

Inorganic Compounds

Focus on Elements Used for Their Therapeutic Effects
Focus on Elements Used for Their Therapeutic Effects

Synthetic Sources

  • Genetic engineering is used to alter bacteria to produce chemicals that are therapeutic and effective
  • Changes in chemical structure can make drugs more potent, more stable, and less toxic

Drug Evaluation

  • Preclinical trials
    • Chemicals tested on laboratory animals
  • Phase I studies
    • Chemicals tested on human volunteers
  • Phase II studies
    • Drug tried on informed patients
  • Phase III studies
    • Drug used in vast clinical market
  • Phase IV studies
    • Continual evaluation of the drug

Legislation

Focus on Federal Legislation Affecting the Clinical Use of Drugs
Focus on Federal Legislation Affecting the Clinical Use of Drugs

Pregnancy Category

FDA Pregnancy Categories
FDA Pregnancy Categories

Controlled Substances

DEA Schedules of Controlled Substances
DEA Schedules of Controlled Substances

Drug Names

  • Chemical name
  • Generic name
  • Trade name

Drug Name

  • Chemical name
    • (+/-)-2-(p-isobutylphenyl) propionic acid
  • Generic name
    • Ibuprofen
  • Trade name
    • Motrin®, Advil®
Mosby Items and Derived Items
Mosby Items and Derived Items

Types of Drugs

  • Over-the-counter drugs
  • Prescription drugs

Over-the-Counter Drugs

  • Drugs considered very safe and useful to patients without a prescription
  • Drugs may previously have been prescription medications (eg, loratadine)

Concerns With OTC Medications

  • OTC drugs can mask the signs and symptoms of underlying disease
  • Taking OTC drugs with prescription medications can result in drug interaction
  • Taking prescription medication incorrectly with OTC drugs could result in serious overdose

Sources of Drug Information

  • Reference books
  • Journals
  • Internet

Chapter 1
Introduction to Drugs
Nurses’ Responsibility
Administering drug
Assessing for adverse drug effects
Intervening to make the drug regimen more tolerable
Providing patient teaching about drugs and the drug regimen
Monitoring and prevention of medication errors
Pharmacology
Pharmacology is the study of the biological effects of chemicals
Health care providers focus on how chemicals act on living organisms
Pharmacotherapeutics
A branch of pharmacology that uses drugs to treat, prevent, and diagnose disease
Pharmacotherapeutics focuses on:
The drug’s effect on the body
The body’s response to the drugs
Drug effects
Therapeutic
Adverse
Sources of Drugs
Plants
Animal products
Inorganic compounds
Synthetic sources
Plants
Animal Products
Animal products are used to replace human chemicals
Used less frequently due to genetic engineering
Synthetic preparations are considered safer
Inorganic Compounds
Synthetic Sources
Genetic engineering is used to alter bacteria to produce chemicals that are therapeutic and effective
Changes in chemical structure can make drugs more potent, more stable, and less toxic
Drug Evaluation
Preclinical trials
Chemicals tested on laboratory animals
Phase I studies
Chemicals tested on human volunteers
Phase II studies
Drug tried on informed patients
Phase III studies
Drug used in vast clinical market
Phase IV studies
Continual evaluation of the drug
Legislation
Pregnancy Categories
Controlled Substances
Drug Names
Chemical name
Generic name
Trade name
Drug Name
Chemical name
(+/-)-2-(p-isobutylphenyl) propionic acid
Generic name
Ibuprofen
Trade name
Motrin®, Advil®
Types of Drugs
Over-the-counter drugs
Prescription drugs
Over-the-Counter Drugs
Drugs considered very safe and useful to patients without a prescription
Drugs may previously have been prescription medications (eg, loratadine)
Concerns With OTC Medications
OTC drugs can mask the signs and symptoms of underlying disease
Taking OTC drugs with prescription medications can result in drug interaction
Taking prescription medication incorrectly with OTC drugs could result in serious overdose
Sources of Drug Information
Package insert
Reference books
Journals
Internet