Pharmacokinetics Flashcards
(32 cards)
Define pharmacokinetics.
the absorption, distribution, and fate of a drug in the body.
What affects the magnitude of a pharmacological effect of a drug?
Its concentration at the site of action
At what level in systemic circulation are drugs distributed?
capillary level
What are various ways we can measure drug concentration in the body?
blood/plasma
urine
saliva
What factors affect the rate at which drugs enter and exit circulation?
- how a drug is delivered
- physiochemical properties of barriers
- chemical properties of drugs and cellular environment
What are the more common routes of drug administration?
oral
IV/infusion
What are the typical characteristics of drugs that are given via IV?
usually protein drugs that are failed to be taken up via oral ingestion
What are disadvantages of IV route of administration?
risk of infection
more severe allergic reactions
What are disadvantages oral route of administration?
multiple barriers to pass through between the intestine and colon
What are advantages of pulmonary route of administration?
fast, quantitative uptake
What affects absorption of a drug?
food dosage pH blood flow other drugs
How does blood flow affect drug absorption?
organs with high blood flow: drugs do not stay around long; but there is a constant flow of the drug to that area
What barriers do drugs pass through when given orally?
start in lumen of intestines
enter cell membrane of endothelial cells of villi
enter capillary endothelial cell membrane and enter bloodstream
Define bioavailability.
rate and extent to which a drug is absorbed and becomes available at the site of action (the proportion of drug administered that reaches systemic circulation)
What affects bioavailability?
first pass effect, barriers, solubility/chemistry, distribution to other tissue
Are all oral drugs absorbed?
No, drugs that need to treat an intestinal condition may not need to be absorbed to act on their target.
What antibiotic is used to treat intestinal infections?
vancomycin
What is the order from most accessible to least accessible of drug targets outside of circulation?
outside of circulation,
within cells,
within the central nervous system
What are different types of barriers drugs may have to pass through?
endothelial barrier
intestinal epithelial barrier
alveolar-endothelial barrier
blood brain barrier
What are various ways for a drug to get past a barrier?
- go around it
* go through it
How do drugs get around a barrier?
they pass between the endothelial cells through fenestrae
How do drugs go through the cell membrane/barriers?
passive diffusion
facilitated diffusion
active transport
What is the P-gp transporter?
an efflux transporter; cancers can develop this and thus don’t respond to drug therapy
What type of superfamily is the Pgp transporter considered?
ABC (ATP binding)
* these transport in and out of the cell