Anatomy and physiology - Pharmacokinetics Flashcards
What is pharmokinetics?
What the body does to drugs
What is lignocaine and what does it do?
A local anaesthetic that blocks sodium channels which stops action potentials and causes local anaesthesia
What is intravenous administration?
injected directly into the bloodstream so reaches the site immediately
hat is an issue with intravenous administration (IV)
There are sodium channels everywhere, so high concentrations can cease activity everywhere
What is a benefit of intravenous administration (IV) other other forms of administration?
All the drug is rapidly absorbed, whereas others and slower and incomplete absorption due to factors such as first pass metabolism
What determines plasma concentration?
Dose, elimination, and route of administration
What determines the effect of a drug?
Number of receptors bound to drugs, which depends on drug concentration which depends on plasma concentration
How do you calculate therepatuic index?
toxic dose/therapeutic dose
What does ED50 mean?
ose that produces therapeutic effect in 50% of the sample
What does LD50 mean?
Dose that kills 50% of the sample
What does Emax mean?
Dose that produces the maximum response of a drug
What is local concentration?
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What four areas of pharmacokinetics determine what happens to a drug in the body?
Absporption
distrubtion
metabolism
elimination
What determines tissue drug concentrations?
Dose, amount and rate
What determines absorption?
Route of administration
Solubility, physical form
What determines elimination?
Renal and hepatic clearance
interactions
What group of enzymes mainly chemically modify the drugs in the liver?
Cytochrome oxidase P450
What happens to the drug in the liver?
Oxidation/reduction or conjugation to make it excretable, resulting in active or inactive metabolitaes
What are the requirmetns for elimination of drigs?
functioning liver and enzymes
What is enzyme inhibition?
A drug inhibits the enzyme so the other drug isnt cleared to quickly and plasma concetration stays high for lomger e.g. grapefruit juice interferes with a number of drugs