Metabolism and Elimination Flashcards
what is elimination
drug excreted or metabolised to some other form
Different ways in which drugs can be excreted
urine/ bile/ expired air/ milk/ sweat saliva
how are drugs eliminated
through more than one route, they are metabolised
where does excretion occur
kidney
where does metabolism occur
liver
what is the definition of clearance
apparent volume of blood cleared of drug per unit time
what does clearance describe
How fast the Irreversible reaction of removal of drug from systemic circulation happens
what is clarifictaion for clearance of drug
drug could still be in body but had already been metabolised
what is the equation for clearance
c= elimination rate/ plasma drug concentration
what can the free unbound drug be eliminated by
metabolism/kidneys to urine/bile ducts to duodenum
what is hepatic elimination
foreign bodies removed unchanged with no metabolite alteration via biliary removal
Recall the process of biliary elimination starting from liver
liver -bile ducts - gall bladder - duodenum - faeces
what are xenobiotics and give examples
foreign bodies such as pesticides, food additives, industrial chemicals
how does human body detoxify chemicals
cytochrome p450
are lipophilic xenobiotics elimiated by kidney
no
can lipophilic molecules be excreted if not metabolised
no
what are the two phases of drug biotransformation
1 -increase polrity of compound
2- increase polarity of comp again
what is a phase 1 reaction
catabolic breakdown
what is phase 2 raction
anabolic buildup
give examplesof phase 1 reaction
oxidation, reduction, hydrolysis
give examples of phase two recations
sulphation/ glucuronidation/acetylation/methylation
where do phase 1 reactions occur
SER in hepatocytes
where do phase 2 reactions occur
cytosol of hepatocyte
how do you name genes
first gene name- family-subfamily- gene no. on aa sequence
which CYPs are essentil for drug metabolism
1/2/3
what is the functoinal unit of kidney and what does it do
nephron- filters blood
how are drugs excreted in urine
collecting duct -renal - pelvis - ureter
why is there no such thing as standard dose
differences in absorption rates/metabolism and elimination
what is the therapeutic range
differnec between minimum EFFECTIVE conc and minimum TOXIC conc
what does therapeutic range provide
indictaion whether drug monitoring is needed
what drugs a large therapeutic window mean
nontoxic
what does a reasonable therap windiw mean
medium toxicity
what does a narrow therap wndow mean
highly toxic
what is the true dose
dose that will have desired effect
what will the true dose depend on
dissolution, absorption, ability to survive metabolism
what can affect metabolism and how
liver/old age/ drug interactions / inhibtion= reduced
liver enzyme induction= increased
what is the connection between half life, metabolism and dose
with a reduced metabolism, half life increased so dose decreases
what is the connection between half life excretion and dose
reduced excretion- increased hald life - lower dose
which is more lipid liking hydrogen or hydroxide
hydrogen
whihc is more lipid liking, methanol or hydroxide
methanol
