Drug Disposition Flashcards
What is the study of drugs in the body across biological membranes from the time of absorption until elimination?
disposition of drugs
4 stages of drug disposition (pharmacokinetics):
Absorption
Distribution
Biotransformation
Excretion
Why is it important to make sure dehydrated patients are rehydrated while getting medical treatment?
Dehydration affects the electrolyte pumps, which will cause decreased absorption of drugs.
What are the factors affecting disposition of drugs?
Cell membranes Concentration gradient Pump mechanisms Site of admin Total body water Plasma protein binding Disease
Type of transport that does not require ATP and involves movement down a concentration gradient and hydrostatic pressure differences across membranes. It is also the most common form of transport.
Passive diffusion
Type of passive diffusion in which contents move through lipid membranes. The majority of drugs are moved through the body in this way.
Simple diffusion
Type of transport in which no ATP is required, and movement occurs down a concentration gradient, but is faster because it is carrier-mediated.
Facilitated Diffusion
Type of transport that uses ATP and a carrier to move contents from low to high concentrations (uphill movement)
Active transport
What type of active transport involves the Na/K ATPase pump, the most abundant AT pump in the body?
Primary active transport
What type of active transport involves cotransport of glucose along with Na+ in the renal tubules?
Secondary active transport
Type of transport known as “cell drinking” in which a cell engulfs drug molecules dissolved in water.
Pinocytosis
T/F: Pinocytosis can interfere with lysosomal function and cause lysosomal rupture.
TRUE
What drug type is transported via pinocytosis and is known to cause renal toxicity due to sequestration in the renal tubules?
Aminoglycosides
What are 3 factors that affect simple diffusion?
Concentration gradient
Lipid solubility
Degree of drug ionization
A drug with higher lipid solubility will cross the membrane ______.
Faster
How do non lipid soluble drugs cross cell membranes?
More dependent on small size to get through membrane pores.
Drugs cross membranes in ______ form.
Non-ionized
Non-ionized drugs will cross the cell membrane _____ than ionized drugs.
Faster
Degree of ionization depends on what 3 factors?
pH of drug
pKa of drug
pH of env in vivo
What does the lipid partition coefficient compare?
Lipid solubility to water solubility
A higher lipid partition coefficient equals a _____ lipid solubility, therefore a ______ diffusion of the drug through biological membranes.
A higher lipid partition coefficient equals a HIGHER lipid solubility, and therefore a GREATER diffusion of the drug through biological membranes.
What do we call the pH at which a weak electrolyte (acid or base) is 50% ionized and 50% nonionized?
pKa
If drug A is 50% ionized and 50% nonionized at a pH of 6, what is the pKa of the drug?
6
Acidic drugs will ionize in _____ environments and basic drugs will ionize in ______ environments.
Alkaline
Acidic
