Pharmacokinetics and Bioavailability Quiz

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