Week 1 part 2 Flashcards
(106 cards)
What is Pharmacokinetics?
The study of the changes in the concentration of a drug during the processes of absorption, distribution, metabolism, and elimination from the body (ADME)
Think what the body does to a drug once administered
What system is essential for delivery of drugs to various tissues?
Vascular system
Once drugs enter into the blood, they can either remain where? 3 things
NAME?
Where can unbound, free floating drugs enter?
Unbound drug enters organs, muscles, fats, and receptors
What 4 characteristics of a drug determine the ability to move to various sites within the body?
NAME?
What are 2 non drug properties that influence uptake?
NAME?
What sized molecules can’t pass through cell membranes?
Molecules with molecular weights greater than 100-200
Smaller molecular sized drugs (agents) cross the lipid barriers and membranes easier
Biologic membranes have small openings or pores
What are the two types of ways molecules can transport across membranes?
-
Passive
Does not require energy
Involves transfer of drug from area of high concentration to area of low concentration -
Active
Requires energy
Faster
Uses carriers that form complexes with drug molecule on the membrane surface
Can involve movement of drug against a concentration gradient i.e. low to high concentration
Many cell membranes have what 2 specialized transport mechanisms?
- Control entry
-
Control exit
Examples include –>
Sugars
Amino acids
Neurotransmitters
Metal ions
What is the terminology for the two directions ions can move in and out of cells?
Efflux
Drive substrates out of cells
Uptake
Transfer substrates into cells
What common transporter requires active energy (active) to be used?
Adenosine triphosphate binding cassette (ABC)
Active pumps requiring energy
Over 300 genes believed to code these transporters
Most act on endogenous substrates
What common transporter allows for passive transport?
Solute carrier transported (SLC)
Control passive movement of solutes down electrochemical gradient
What are most drugs salts of?
Weak acids
Weak bases
Drugs behave like a chemical in a solution when introduced to the human body
As an acid or base, drugs exist in solutions in…?
NAME?
Key points to know about ionized drugs –>
Water soluble (hydrophilic)
Unable to easily penetrate lipid cell membranes
Key points to know about nonionized drugs –>
Lipophilic
Diffuses across cell membranes like blood- brain/gastric/placental barriers
What is the meaning of pKa?
The pKa is the negative log of the equilibrium constant for the dissociation of the acid or base
The pH of a drug where 50% of the drug is ionized and the other 50% is nonionized
What determines the degree of ionization of an agent?
Acids and bases degree of ionization is determined at a particular site by the dissociation constant (pKa) of the agent and its pH gradient across the membrane
What is the relationship between pH, pKa, and Ionization for weak acids and bases?
What is ion trapping?
When an unionized drug crosses a membrane into a more acidic environment (lower pH) –> This unionized drug now becomes ionized because of this lower pH, and now that it is ionized, it can’t cross back through the membrane.
Changes in protein binding have long been theorized to ________________.
Changes in protein binding have long been theorized to influence a drugs clinical effect
What are some diseases in which you would expect lower plasma protein levels?
NAME?
Two or more highly protein-bound drugs can cause __________ _________.
Drug interactions –> Although this is rare
Drugs bound to plasma proteins become trapped within what?
Remain trapped within circulatory system
Drug-protein molecules are too large to diffuse through blood vessel membrane –> Albumin quantitatively most abundant plasma protein