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Chemotherapeutic Agents Nursing Pharmacology

Anti-infective Agents

Anti-infective Agents

Drug Therapy Across the Lifespan

Drug Therapy Across the Lifespan
Drug Therapy Across the Lifespan

Development of Anti-infective Therapy

  • 1920s
    • Paul Ehrlich worked on developing a synthetic chemical effective against infection-causing cells only
    • Scientists discovered penicillin in a mold sample
  • 1935
    • The sulfonamides were introduced

Mechanisms of Action

  • Interfere with biosynthesis of the bacterial cell wall
  • Prevent the cells of the invading organism from using substances essential to their growth and development
  • Interfere with steps involved in protein synthesis
  • Interfere with DNA synthesis
  • Alter the permeability of the cell membrane to allow essential cellular components to leak out

Mechanism of Anti-infective Agents

Mechanism of Anti infective Agents
Mechanism of Anti infective Agents

Anti-infective Activity

  • Anti-infectives vary in their effectiveness against invading organisms
  • Some are selective: they are effective only for a small number of organisms
  • Bactericidal: kill the cell
  • Bacteriostatic: prevent reproduction of the cell

Narrow Spectrum vs Broad Spectrum

  • Narrow spectrum of activity
    • Effective against only a few microorganisms with a very specific metabolic pathway or enzyme
  • Broad spectrum of activity
    • Useful in treating a wide variety of infections

Human Immune Response

  • Goal of anti-infective therapy is reduction of the population of the invading organism
  • Drugs that eliminate all traces of any invading pathogen might be toxic to the host as well
  • Immune response is a complex process involving chemical mediators, leukocytes, lymphocytes, antibodies, and locally released enzymes and chemicals

Problems With Treating Infections in Immunosuppressed Patients

  • Anti-infective drugs cannot totally eliminate the pathogen without causing severe toxicity in the host
  • These patients do not have the immune response in place to deal with even a few invading organisms

Resistance

  • Anti-infectives act on a specific enzyme system or biological process; many microorganisms that do not act on a specific system are not affected by the particular drug
  • This is considered natural or intrinsic resistance to that drug

Acquired Resistance

  • Microorganisms that were once sensitive to the particular drug have begun to develop acquired resistance
  • This results in serious clinical problems

Ways Resistance Develops

  • Producing an enzyme that deactivates the antimicrobial drug
  • Changing cellular permeability to prevent the drug from entering the cell
  • Altering transport systems to exclude the drug from active transport into the cell
  • Altering binding sites on the membranes or ribosomes, which then no longer accept the drug
  • Producing a chemical that acts as an antagonist to the drug

Preventing Resistance

  • Limit the use of antimicrobial agents to the treatment of specific pathogens sensitive to the drug being used
  • Make sure doses are high enough, and the duration of drug therapy long enough
  • Be cautious about the indiscriminate use of anti-infectives

Identification of the Pathogen

  • Identification of the infecting pathogen is done by culture
  • A culture of a tissue sample from the infected area is done
    • A swab of infected tissue is allowed to grow on an agar plate
    • Staining techniques and microscopic examination identify the bacterium
  • Stool can be examined for ova and parasites

Sensitivity of Pathogen

  • Shows which drugs are capable of controlling the particular microorganism
  • Important to be done for microorganisms that have known resistant strains
  • Along with a culture, identifies the pathogen and appropriate drug for treatment

Factors Affecting Prescribing Anti-infective Agents

  • Identification of the correct pathogen
  • Selection of the right drug
    • One that causes the least complications for that particular patient
    • One that is most effective against the pathogen involved

Combination Therapy

  • Use of a smaller dosage of each drug
  • Some drugs are synergistic
  • In infections caused by more than one organism, each pathogen may react to a different anti-infective agent
  • Sometimes, the combined effects of the different drugs delay the emergence of resistant strains

Adverse Reactions to Anti-infective Therapy

  • Kidney damage
  • Gastrointestinal (GI) tract toxicity
  • Neurotoxicity
  • Hypersensitivity reactions
  • Superinfections

Prophylaxis of Anti-infective Agents

  • People traveling to areas where malaria is endemic
  • Patients who are undergoing gastrointestinal or genitourinary surgery
  • Patients with known cardiac valve disease, valve replacements, and other conditions requiring invasive procedures
Categories
Chemotherapeutic Agents Nursing Pharmacology

Introduction to Cell Physiology

Introduction to Cell Physiology

Chemotherapeutic Agents

  • Alter cellular function or disrupt cellular integrity, causing cell death
  • Prevent cellular reproduction, eventually leading to cell death

Chemotherapeutic Drugs

  • Destroy organisms that invade the body
    • Bacteria, viruses, parasites, protozoa, fungi
  • Destroy abnormal cells within the body
    • Neoplasms and cancers

Parts of a Human Cell

  • Nucleus
  • Cell membrane
  • Cytoplasm

Structure of a Cell

Stucture of a Cell
Stucture of a Cell

Cell Nucleus

  • Contains genetic material
    • Necessary for cell reproduction
    • Regulates cellular production of proteins
  • Each cell is “programmed” by the genes for the production of specific proteins
    • Allows the cell to carry out its function
    • Maintains cell homeostasis or stability
    • Promotes cell division

Cell Membrane

  • Surrounds the cell
  • Separates the intracellular fluid from the extracellular fluid
  • Essential for cellular integrity

Structure of a Lipid Cell Membrane

Structure of a Lipid Cell Membrane
Structure of a Lipid Cell Membrane

Organelles of the Cytoplasm

  • Mitochondria
  • Endoplasmic reticulum
  • Free ribosomes
  • Golgi apparatus
  • Lysosomes

Components of Cell Membrane

  • Cell membrane is made up of lipids and proteins
  • Several lipids make up the cell membrane
    • Phospholipids
    • Glycolipids
    • Cholesterol
  • Lipid layer provides a barrier for the cell and maintains homeostasis of the cell

Receptor Sites

  • Found on the cell membrane
  • Specific receptor sites allow interaction with various chemicals

Identifying Markers

  • Surface antigens
  • Important in the role of cellular immunity
  • Histocompatibility proteins allow for self-identification
  • The body’s immune system recognizes these proteins and acts to protect self-cells and to destroy non–self-cells

Channels

  • Channels or pores allow for the passage of substances into and out of the cell
  • Some drugs are designed to affect certain channels within the cell

Cell Properties

  • Endocytosis
    • Involves incorporation of material into the cell
    • Pinocytosis and phagocytosis occur
  • Exocytosis
    • Allows a cell to move a substance to the cell membrane and secrete the substance outside the cell
    • Hormones, neurotransmitters, and enzymes are excreted into the body by this process

Homeostasis of the Cell

  • Passive transport
    • Happens without the expenditure of energy and can occur across any semipermeable membrane
    • Occurs by diffusion, osmosis, and facilitated diffusion
  • Active transport
    • Energy-requiring process
    • Movement of particular substances against a concentration gradient
    • Important in maintaining cell homeostasis

Passive Transport

  • Diffusion
    • Does not require energy
    • The movement of solutes from a region of high concentration to a region of lower concentration across a concentration gradient
  • Osmosis
    • Does not require energy
    • Movement of water from an area low in solutes to an area high in solutes

Phases of the Cell Cycle

  • G0 phase
    • Resting phase
  • G1 phase
    • Gathering phase
  • S phase
    • Synthesizing phase
  • G2 phase
    • Last substances needed for division are collected and produced
  • M phase
    • Actual cell division occurs, producing two identical daughter cells

Cell Cycle

Cell Cycle
Cell Cycle

Cell Physiology

  • May alter the cell membrane, causing the cell to rupture and die
  • May deprive the cell of certain nutrients, altering the proteins that the cell produces and interfering with normal cell functioning and cell division
  • May affect the normal cells of patients to some extent