Questions and Answers
What is the primary purpose of drug therapy?
Which key property of a drug refers to its ability to specifically target the desired action without affecting non-desired targets?
What does the term 'concentration' in relation to drug properties refer to?
What aspect of a drug relates to how long it maintains its therapeutic effect before being depleted?
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Which of the following statements best describes the concept of drug selectivity?
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What is a common way that antibacterials interfere with bacterial life?
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Which structure can antibacterials interfere with to kill or inhibit bacteria?
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What is a characteristic of antimicrobial agents?
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Which of the following mechanisms is NOT targeted by antibacterials?
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How do antibacterials achieve selectivity towards bacteria without harming the host?
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The two common routes of administration are _____ and ________
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What are the three common routes of injection?
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Which of the following ADME principles primarily determines the duration of a drug's effect in the body?
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Which ADME principle is directly responsible for the concentration of a drug in the blood after administration?
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Which ADME principle explains why a drug might be more concentrated in certain tissues than others?
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Which ADME principle is MOST influenced by the drug's chemical structure and properties?
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Which ADME principle is primarily responsible for eliminating a drug from the body?
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What does pharmacodynamics primarily study?
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Which of the following best describes potency in pharmacology?
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How is the relationship between drug concentration and its effects characterized?
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What aspect of pharmacokinetics involves the elimination of the drug from the body?
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What relationship do PK and PD together represent?
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What is the primary difference between bacteriostatic and bactericidal agents?
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Which of the following statements is TRUE regarding the spectrum of activity of antimicrobials?
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The minimum inhibitory concentration (MIC) of an antibiotic is defined as:
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Which of the following is NOT a factor that influences the killing of a pathogen within the host?
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Which of the following describes the killing pattern of an antimicrobial that exhibits a time-dependent effect?
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What is the purpose of setting breakpoints for antimicrobial agents?
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What is the maximum concentration of a drug residue in an animal consumable product that is legally tolerated?
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What is the time period that must elapse between the last administration of a veterinary medicine and the slaughter or production of food from that animal?
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What is a factor that influences the choice of an antimicrobial agent?
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What is defined as the daily intake of a substance that, over the entire lifetime of a human, appears to be without adverse effects or harm to the health of that human?
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What is the primary way in which acquired antibiotic resistance arises?
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How does the use of antibiotics contribute to the spread of antibiotic resistance?
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Which of the following statements BEST describes the role of innate resistance in bacteria?
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How do resistant bacteria contribute to the spread of antibiotic resistance?
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Which of the following is NOT a direct consequence of the increasing prevalence of antibiotic resistance?
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Study Notes
Drug Therapy (Pharmacotherapy)
- Definition: A medical treatment that utilizes one or more drugs to provide symptomatic relief, treat the underlying condition, or act as a prevention for other diseases.
Key Properties of a Drug
- Selectivity: A drug's ability to target desired targets while avoiding non-desired targets.
- Concentrations: A drug's ability to achieve sufficient concentrations at the site of action while avoiding toxicity.
- Time: A drug's ability to maintain its effect over time without depleting its potency.
Antimicrobial Agents
- An antimicrobial agent is a substance that can kill microbes (bacteria, fungi, virus) or prevent their multiplication, reducing their pathogenic effect.
- Antimicrobial agents can be of natural, semisynthetic or synthetic origin.
Mechanism of Action
- To interfere with bacterial cell life or growth, antibacterials must interact with a vital structure or block a metabolic pathway.
- This interaction should not cause direct toxicity for hosts receiving treatment.
Targets of Antimicrobial Action
- Cell wall
- Plasma membrane
- Ribosomes
- Metabolic pathways
- DNA synthesis
- RNA synthesis
Principles of Drug Therapy
- The ADME principle is a crucial concept in drug therapy, consisting of four key stages:
ADME Principle
- Absorption: The process by which the concentration of a drug increases in the blood after administration
- Distribution: The stage where the drug is dispersed throughout the body and its concentration is determined in various tissues
- Metabolism: The process of determining the metabolites of a drug, which affects its efficacy and toxicity
- Excretion: The final stage, where the drug is eliminated from the body through feces, urine, or other means, and its concentration is measured in these waste products
Pharmacokinetics (PK)
- Study of what the body does to the drug, involving four processes: absorption, distribution, metabolism, and excretion
Pharmacodynamics (PD)
- Study of what the drug does to the body and the target, including intensity of therapeutic effect and adverse effects
- Involves understanding the drug's effect on the body and the target
PK/PD Relationship
- Combination of PK and PD, representing an exposure/response relationship
- Exposure refers to the drug's presence in the body, while response refers to its effect on the body and target
Dose-Response Relationships
- Drug effect is a function of both dose and time
- Response to concentration is often complex and nonlinear
- Potency is a measure of the drug's effectiveness, defined as the concentration at which 50% of the maximum effect is achieved
Antibacterial Effects
- Bactericidal agents kill bacteria, reducing the total number of viable organisms, and usually require active bacterial growth.
- Bacteriostatic agents inhibit bacterial growth and replication, allowing the host immune system to eliminate the pathogen.
Spectrum of Activity
- Narrow-spectrum antimicrobials act against a limited group of bacteria.
- Broad-spectrum antimicrobials act against several groups of bacteria, including G+ and G- groups.
- The spectrum of activity is based on the susceptibility of the wild-type population of bacterial species.
In Vitro Evidence
- Minimum Inhibitory Concentration (MIC) is the lowest concentration of antibiotic that completely inhibits growth of a specific organism.
- Minimum Bactericidal Concentration (MBC) is the lowest concentration of antibiotic that kills bacteria.
- Disk diffusion test measures the diameters of inhibition zones around disks containing the antibiotic tested.
Antibiotic Efficacy in Vivo
- Antibiotic effectiveness depends on binding to the target site in the bacterium, sufficient concentration within the bacterium, and sufficient time to cause an effect.
- Antimicrobial effect is dependent on both concentration and time.
- Antibiotics can be classified according to their pattern of activity:
- Concentration-dependent killing pattern: increased drug concentration leads to increased effect.
- Time-dependent killing pattern: the duration of exposure is more important than the concentration.
- Hybrid pattern: both concentration and time are important.
- The area under the serum concentration curve (AUC) measures the concentration and duration of antibiotic levels above the target MIC during a dosing interval.
Categorical Classification of Bacterial Strains
- Bacterial strains are categorized as Susceptible (S), Intermediate (I), or Resistant (R)
Criteria for Setting Breakpoints for Pathogen A
- Microbiological criteria: in vitro testing
- Pharmacological criteria: PK/PD indexes and response to treatment
- Clinical criteria: best evidence from literature
Definitions in Pharmacology and Toxicology
- ECOFF: epidemiological cut-off
- Acceptable Daily Intake (ADI): daily intake of a substance that appears to be without adverse effects or harm to human health over a lifetime
- Maximum Residue Limits (MRLs): maximum concentration of a drug residue in animal consumable products that is legally tolerated
- Withdrawal Period: time between last administration of a veterinary medicine and slaughter/production of food to ensure food does not contain levels of medicine exceeding MRLs
Factors Affecting Drug Choice
- Infection type and severity
- Antimicrobial action and effect
- Veterinarian's experience
- Cost of treatment
- Compliance of treatment regimen
- Pharmacokinetic drug properties
- Host factors
- Toxicity of the drug
Antibiotics Resistance Mechanisms
- Innate resistance is a natural, preexisting genomic property of bacteria, often due to a mutation or gene.
- Acquired resistance is obtained by bacteria through mutation or horizontal gene transfer, which occurs via conjugation, transduction, and transformation.
AMR Generation and Dissemination
- Resistant bacteria can pass on their resistance to other bacteria, contributing to the spread of antibiotic resistance.
- The use of antimicrobials selectively kills bacteria that are not resistant, increasing the proportion of resistant bacteria in a population.
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Description
This quiz covers the basics of drug therapy, also known as pharmacotherapy, including its application, key properties of a drug, and more. Test your understanding of selectivity, concentrations, and time in drug therapy.