Pharmacokinetics Flashcards
What is pharmacokinetics
the study of the effect the body has on the drug
What are the different transports of the drugs?
through either active or passive transport
What are the active transports
a process that moves against the gradient low to high. IT uses the energy of ATP to move molecules from low to high concentration. For some of the types of transporters, they may be a SLC or ABC transporters to help with the process. The types of transport are: facilitated and drug transporters
What are the passive transports
it is a process where molecules use the force of the gradient (which is high to low Concentration) to move molecules from one region to another. Types are: diffusion and paracellular
What molecules can diffuse cross the membrane
gases, small polar and hydrophobic molecules
What molecules cannot diffuse cross the membrane
large polar and charged molecules
What are SLC transporters
it is a type of transporter that is usually seen in facilitative transport. it is active in the secondary active transport of het he antiport (Na and Ca exchanger) and the symport ( Na/Glucose transporter in the GI)
What are ABC transporters
they are transporters that utilize the energy of ATP binding and hydrolysis to carry out certain biological processes across membrane. it is in primary active transport.
What is bioavailability
In pharmacology, Bioaviilabilty is the fraction of administered drug that reaches the system circulation. for ex. 100 mg of drug is administered orally and 70mg is absorbed, then the bioavailiabilty is 70%.
What are the factors that influence bioavailability?
First pass hepatic bioavailabilty
solubility of the drug
chemical instability
nature of the drug formulation
What are phase 1 reactions
reactions that render a molecule more polar by attaching an ionizable group to the molecule. characteristics are OH, NH2 and SH. after phase 1 reaction drug effects weakens. prodrug are converted to active form ex.
What are phase 2 reactions
reactions that render the molecule more polar by attaching a polar molecule to the parent compound
What is the 4 parts of Pharmokinetics
absorption
distribution
Metabolism
Elimination
What is absorption
site or route of the administration ( directly or indirectly) into the bloodstream
What are the factors that play into the rate and efficacy of the absorption of the drug
environment
the drug characteristics
route of administration
What is Distribution
it deals with the movement of the drug once in the plasma. it has the option to move or reverse and leave the bloodstream and go to the interstitial and intracellular fluids
What is the metabolism
How the drug is handed biochemically by the body
What is excretion
deals with how the drug leaves the body through either bile, urine or feces
What is facilitated diffusion
is the movement of large molecules from high to low concentration due to the transmembrane carrier proteins that go through a conformational change to bring the molecules in the interior of the cel
What are the factors that influence absorption
effect of pH on drug absorption blood flow total surface area contact time at the absorption surface Expression of P-glycoprotein
What are the function of the P-glycoprotein
it is a transmembrane transporter protein that is responsible for transporting various molecules like drugs across the membrane.
What is first pass effect
is a phenomenon of drug metabolism whereby the concentration of a drug is greatly reduced before it reaches the systemic circulation due to the gut wall or the liver metabolizes the drug rapidly.
what type of drug is typically readily to diffuse across the membrane hydrophobic or hydrophilic
hydrophobic
What is the volume of distribution
the volume of distribution (VD, also known as apparent volume of distribution) is the theoretical volume that would be necessary to contain the total amount of an administered drug at the same concentration that it is observed in the blood plasma.[1] It is defined as the distribution of a medication between plasma and the rest of the body after oral or parenteral dosing.[2]
The VD of a drug represents the degree to which a drug is distributed in body tissue rather than the plasma.
What is the correlation between the Vd and the tissue concentration
VD is directly correlated with the amount of drug distributed into tissue; a higher VD indicates a greater amount of tissue distribution. A VD greater than the total volume of body water (approximately 42 liters in humans[3]) is possible, and would indicate that the drug is highly distributed into tissue.
What are the 3 compartments that the drug can distribute to after being administered?
Plasma compartment
Extracellular fluid
Total body water
What is plasma compartment
this tends to happen to molecules that are to large to move effectively out to the capillaries thus making it stuck in the plasma this distribute through 6% of the body.
What is extracellular compartment
if the molecules are small but hydrophilic, then the molecules can move into the intestitial fluid. this distributes through 20% of the body
What is the total body water
- if the molecules are small and they are hydrophilic it can move all the way through the intracellular fluid and it distributes through 60% of the body.
What is the formula for Vd
Vd= dose/ C0
What is the relationship between Vd and the half life
drug elimination depends on the amount of drugs delivered to the liver or kidney. it depends on the blood flow and the fraction in the plasma. If Vd is high than the half life of the drug is high and extend the duration of action of the drug.
