Pharmacology Flashcards
What is pharmacodynamics?
Pharmacodynamics is the study of drug action in humans.
Where do drugs typically act on?
Drugs act on receptors or physiological mechanisms such as enzymes, ion channels, or transport channels at the nucleus.
Why do individuals respond to drugs differently?
Due to genetic variation, individuals will respond to drugs differently.
List the important sites of drug action.
Receptors, enzymes, and ion channels.
What does the effectiveness of a drug on a receptor depend on?
- number of receptors available
- receptor configuration & binding of drug
- physiological processes triggered by drug binding
What does the effectiveness of a drug on an enzyme depend on?
- intrinsic activity of enzyme
- drug binding
What does the effectiveness of a drug on ion channels depend on?
- number of channels
- conformation of channels
What is the difference between agonist and antagonist?
The main difference between agonists and antagonists is that an agonist provokes a cellular response by binding to a receptor on the cell. An antagonist opposes the action by binding to the receptor, i.e., it blocks these receptors and renders them ineffective. In other words, the agonists turn the receptors on, and the antagonists turn them off.
What does pharmacokinetics concern?
Pharmacokinetics is the study of what the body does to the drug.
What happens to the drug after administration?
The drug must:
- travel the body and reach target site
- remain at target long enough, and at appropriate concentration
- be eliminated from the body in a consistent, predictable way
What are the factors that affect drug concentration in the body?
- bioavailability: e.g absorption from stomach
- first pass metabolism: activation or breakdown by liver enzymes
- clearance: metabolism & elimination through urine
What is bioavailability?
Bioavailability refers to the proportion of parent drug that passes into systemic circulation after administration.
What are the oral determinants of bioavailability?
- amount of drug absorbed
- amount of drug lost in feces
- amount broken down by liver enzymes (first pass metabolism)
How can bioavailability be calculated?
Bioavailability can be calculated by comparing the amount in circulation after oral dose with the amount in circulation after iv dose.
What is half-life the main determinant of?
Half-life value is the main determinant of the dosing regimen (how much & how often).
