Exam 1: Disposition of Drugs Flashcards
Study of the movement of drugs in the body across biological membranes from the time of absorption until elimination?
Pharmacokinetics
What are the 4 stages of drug disposition?
- Absorption
- Distribution
- Biotransformation
- Excretion
Factors affecting disposition of the drug:
- biological cell memb
- conc. gradient
- Pump mech.
- site of admin.
- Total body water
- plasma prtoein binding
- disease
List 4 properties of the biological cell memb.
- phospholipid bilayer
- memb. proteins and carbohydrates
- cell junctions
- aqueous pores
List 4 mechanisms of transport across cell membranes:
- Passive diffusion
- Facilitated diffusion
- Active transport
- Pinocytosis
Type of transport that does not require energy
Passive diffusion
What are the 3 mechanisms of passive diffusion
- transmembrane
- paracellular
- simple diffusion
Movement by passive diffusion through aqueous protein channels in the cell memb.
Transmembrane
Movement via filtration through intracellular aqueous pores
Paracellular
Movement through lipid memb.
Simple diffusion
The majority of drugs move through the body via _____
Simple diffusion
T/F Energy is not required for facilitated diffusion
T
T/F Active transport needs both a carrier and ATP
T
T/F Active transport moves drugs from high conc. to low
F. low to high
Na+/K+ ATPase transport pump is an example of primary or secondary active transport?
Primary
Na dependent glucose transporters are examples of primary or secondary active transport
Secondary
Specific type of endocytosis where cell engulfs the drug molecules dissolved in water “cell drinking”
Pinocytosis
T/F Facilitated diffusion moves down the conc. gradient?
T
T/F Facilitated diffusion requires a carrier and energy
F no energy
T/F Facilitated diffusion is saturable
T
T/F in facilitated diffusion the substance can be transported in or out of cell
T
T/F passive diffusion moves down the concentration gradient
T
T/F Passive diffusion requires energy
F
T/F Facilitated diffusion is the most common form of transport
F. Passive diffusion
T/F Active transport moves uphil from llow to high conc.
T
T/F Active transport uses symporters and anitporters
T
T/F active transport is not saturable
F
T/F Pinocytosis can be toxic
t
T/F Pinocytosis does not work if drug is dissolved in water
F. must be
What are the 3 factors that affect simple diffusion
- Conc. gradient
- Lipid solubility
- Degree of drug ionization
T/F. The higher the lipid solubility of the drug the faster crossing the cell memb
T
T/F. membranes are more permeable to ionized forms of drugs
F. non ionized
T/F Drugs cros biological membranes in non ionized forms
T
T/F rate of diffusion depends on degree ofionization
T
What 3 things does degree of ionization depend on?
- pH of the drug
- pKa of the drug
- pH of environment in vivo
T/F weakly basic drugs are more ionized in alkaline solutions
F. acidic solutions
Equal to the pH of the mediam at which the dissolved drug is 50% ionized and 50% not
pKa
Henderson Hasselbach equation can be used to determine the ____
degree of ionization
