Farma Flashcards
(60 cards)
What is the primary determinant of drug absorption through membranes?
Lipid solubility of the drug.
Define bioavailability
The fraction of an administered dose of a drug that reaches the systemic circulation in its active form.
What is the significance of the first-pass effect?
It reduces the bioavailability of drugs metabolized in the liver before reaching systemic circulation.
Name the most common route of drug excretion
Renal (urine).
What is volume of distribution (Vd)?
Theoretical volume that relates the amount of drug in the body to its plasma concentration.
How does protein binding affect drug distribution?
It decreases the free, active form of the drug available for action.
What is clearance (CL)?
Volume of plasma from which the drug is completely removed per unit time.
Explain half-life (t½) of a drug
Time required for the plasma concentration of a drug to decrease by half.
What type of kinetics do most drugs follow?
First-order kinetics.
What is the major site of drug metabolism?
The liver.
Differentiate between phase I and phase II metabolism
Phase I involves modification reactions (oxidation, reduction), and phase II involves conjugation reactions.
Define prodrug
An inactive compound that is metabolized into an active drug.
Which organ primarily regulates drug excretion?
Kidneys.
What is the therapeutic index?
Ratio of the toxic dose to the effective dose of a drug.
Describe competitive antagonism
An antagonist that binds reversibly to the same receptor as the agonist.
What is the significance of a drug’s affinity?
It determines how tightly a drug binds to its receptor.
Define efficacy in pharmacology
The maximum effect a drug can produce.
What does a full agonist do?
Produces a maximal biological response.
Define partial agonist
Binds to the receptor but produces a less-than-maximal response.
What is an inverse agonist?
Produces the opposite effect of an agonist at a receptor.
Name a mechanism of drug transport that requires energy
Active transport.
What is the role of P-glycoprotein?
It acts as a drug efflux pump, reducing drug absorption.
What is the effect of ionization on drug absorption?
Ionized drugs are less lipid-soluble and poorly absorbed.
How does pH affect weak acid drug absorption?
Weak acids are better absorbed in acidic environments.