Pharmokinetics Flashcards
(32 cards)
What are the positives of oral administration?
Convenient, economic, safety
OD and severe allergic rxn are less likely
What are the negatives of oral administration?
Patient compliance, may not reach optimum concentration
What are the most important sites of absorption for oral drugs?
Stomach and small intestine
What structures are lined with endothelium?
Heart, blood vessels, lymphatics, and serous cavities
Most drugs need to be _____________ enough to pass through a cell membrane.
Lipophilic
What is a partition coefficient?
Measures ability for drug to diffuse
Larger PC = more likely it will be absorbed
T/F: Charges and polar moities will make molecules less likely to diffuse through the cell membrane.
True
What is the stomachs pH at rest? RIght after a high protein meal?
Rest: 4-5
Post-meal: 1-2
Molecules with a low pKa (acidic) will be absorbed better in the ________.
Stomach
Molecules with a high pKa (bases) will be absorbed better in the __________.
Small intestine
________ are always open but _________ only let things in when they’re activated.
Pores; channels
____________ use ATP and are often used to kick proteins out of cells.
ABC transporters
*if over-expressed - will lead to drug resistance
_____________ exchange Na+ or K+ and are important for transport of certain drugs that are organic acids or bases.
SLC transporters
What are two major factors that make the small intestine better for absorption?
- More surface area
2. More time (6-8 hrs)
T/F: Gastric emptying can take longer with food.
True
Why do some drugs absorb better when given intramuscularly or subcutaneously than when taken orally?
Capillaries in these areas have gaps in their endothelium making it easier to get into the bloodstream
What is the volume of distribution?
Provides an indication of how a drug is distributed
Administered amount/concentration in plasma
If a drug has a volume of distribution of 3 L, where is the drug in the body?
Just sitting in the plasma
What would you expect the volume of distribution to be of a drug that is in the blood and interstitial space but not in the cells?
12 L
3L in plasma, 9L in interstitial space
If a drug has a distribution volume that is very very high what does this mean?
There is a very low concentration in the blood plasma - the drug has gone somewhere else
T/F: Drugs which are more polar, more highly ionized, and with high plasma binding capabilities will have higher volumes of distribution.
False
Non-polar, low rates of ionization, low plasma binding capabilities
T/F: Volume of distribution will be decreased during dehydration.
True
_________ are membrane bound enzymes that metabolize drugs.
Microsomes
Where are microsomes found?
Smooth E.R. Of hepatocytes
