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Questions and Answers
What does the study of pharmacokinetics involve?
What does the study of pharmacokinetics involve?
What determines the bioavailability of a drug?
What determines the bioavailability of a drug?
What is the result of plasma protein binding on drug distribution and elimination?
What is the result of plasma protein binding on drug distribution and elimination?
What is the primary organ responsible for drug metabolism?
What is the primary organ responsible for drug metabolism?
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What is the effect of the first-pass effect on drug bioavailability?
What is the effect of the first-pass effect on drug bioavailability?
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What is the outcome of the Phase I reactions in drug metabolism?
What is the outcome of the Phase I reactions in drug metabolism?
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What is the primary purpose of analyzing the concentration of a drug in the blood and tissues over time in pharmacokinetics?
What is the primary purpose of analyzing the concentration of a drug in the blood and tissues over time in pharmacokinetics?
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What is the unit of measurement for bioavailability?
What is the unit of measurement for bioavailability?
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What is the primary protein involved in plasma protein binding?
What is the primary protein involved in plasma protein binding?
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What is the primary difference between Phase I and Phase II metabolism reactions?
What is the primary difference between Phase I and Phase II metabolism reactions?
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What is the effect of plasma protein binding on the distribution of a drug?
What is the effect of plasma protein binding on the distribution of a drug?
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What is the site of the first-pass effect in drug metabolism?
What is the site of the first-pass effect in drug metabolism?
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Study Notes
Pharmacokinetics
- Study of what the body does to a drug
- Involves absorption, distribution, metabolism, and excretion (ADME)
- Describes the time course of drug concentrations in the body
Bioavailability
- Fraction of administered dose that reaches systemic circulation
- Determined by absorption rate, gut wall metabolism, and first-pass effect
- Affects drug efficacy and toxicity
Plasma Protein Binding
- Binding of drugs to proteins in blood plasma (e.g., albumin, alpha-1 acid glycoprotein)
- Affects drug distribution, metabolism, and elimination
- Free drug concentrations are responsible for pharmacological effects
Drug Metabolism
- Process of converting drugs into more water-soluble compounds for excretion
- Occurs primarily in liver via Phase I (oxidation, reduction, hydrolysis) and Phase II (conjugation) reactions
- Influenced by enzyme induction, inhibition, and genetic polymorphisms
First-pass Effect
- Process by which orally administered drugs are metabolized by liver and gut wall before reaching systemic circulation
- Reduces bioavailability and increases inter-individual variability
- Can be affected by drug properties, liver function, and gut flora
Pharmacokinetics
- Study of the body's effects on a drug, including absorption, distribution, metabolism, and excretion (ADME)
- Describes the time course of drug concentrations in the body
Bioavailability
- The fraction of an administered dose that reaches systemic circulation
- Determined by absorption rate, gut wall metabolism, and first-pass effect
- Affects drug efficacy and toxicity, with higher bioavailability generally leading to greater efficacy
Plasma Protein Binding
- The binding of drugs to proteins in blood plasma, such as albumin and alpha-1 acid glycoprotein
- Affects drug distribution, metabolism, and elimination, as bound drugs are not available for pharmacological effects
- Only free drug concentrations are responsible for pharmacological effects
Drug Metabolism
- The process of converting drugs into more water-soluble compounds for excretion
- Occurs primarily in the liver via Phase I (oxidation, reduction, hydrolysis) and Phase II (conjugation) reactions
- Influenced by enzyme induction, inhibition, and genetic polymorphisms, which can affect drug efficacy and toxicity
First-pass Effect
- The process by which orally administered drugs are metabolized by the liver and gut wall before reaching systemic circulation
- Reduces bioavailability and increases inter-individual variability due to differences in liver function and gut flora
- Can be affected by drug properties, such as lipophilicity, and the activity of enzymes involved in metabolism
Pharmacokinetics
- Study of the movement of drugs within the body
- Describes Absorption, Distribution, Metabolism, and Excretion (ADME) of a drug
- Involves analysis of drug concentration in blood and tissues over time
Bioavailability
- Extent to which a drug becomes available to the body
- Measured as the ratio of Area Under the Curve (AUC) to the dose administered
- Factors affecting bioavailability:
- Route of administration
- Dose and dosing regimen
- Drug formulation and manufacturing
- Patient-specific factors (e.g. age, disease state)
Plasma Protein Binding
- Binding of a drug to proteins in the bloodstream, primarily albumin
- Affects drug distribution and elimination
- Factors influencing protein binding:
- Drug properties (e.g. lipophilicity, molecular weight)
- Concentration of binding proteins
- Presence of other substances competing for binding sites
Drug Metabolism
- Process by which the body breaks down and eliminates a drug
- Occurs primarily in the liver, with some metabolism in other tissues
- Phase I metabolism: oxidation, reduction, and hydrolysis reactions
- Phase II metabolism: conjugation reactions (e.g. glucuronidation, sulfation)
- Factors influencing metabolism:
- Genetic variations in metabolizing enzymes
- Induction or inhibition of enzymes by other substances
- Liver function and disease state
First-pass Effect
- Process by which a drug is metabolized and eliminated before reaching systemic circulation
- Occurs primarily in the liver, with some metabolism in the gut wall
- Reduces bioavailability of a drug
- Factors influencing the first-pass effect:
- Dose and dosing regimen
- Route of administration (e.g. oral vs. intravenous)
- Liver function and disease state
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Description
Test your knowledge on pharmacokinetics, bioavailability, and plasma protein binding, including absorption, distribution, metabolism, and excretion of drugs.
