Week 1 Flashcards
(136 cards)
what is pharmacokinetics?
translocation and metabolism of drugs Absorption Distribution Metabolism Elimination
food in, exocrine secretoin, absorption, excretion.
describe Absorption?
oral, most common, can be intravenous straight to plasma
Solublity - water, lipid.
Ionisations status pKa - weak acids and weak bases.
what is Vd?
volume of plasma that would contain the total body content off the drug at the conc equal to the plasma
Vd = amount of drug in body / conc of drug in plasma
drugs with a HIGH Vd have a high conc in extravascular tissues.
describe metabolism?
Phase 1/ Phase 2 reactions.
Drug - Phase 1 - Derivative - Phase 2 - Conjugate , increase in H2O solubility as it goes on.
Phase 1 - describe it?
includes oxidation, hydrolysation, hydrolysis. derivative is made
Phase 2 - desicbe it and give some reactions?
conjugate made common conjugates in cats - glucuronyl - glucorndation sulphate - suplhation methyl - methylation common in dogs - acetyl - acetylation.
Phase 1 - give some common reactions?
reactions - Locations - enzymes oxidation Liver. Cytochrome P450 reduction. lungs hydrolysis skin hydration. kidney
what does Cytochrome P450?
cycle eneyxme reaction
DOGS - greyhounds deficient in subtype of P450,
can use at different doses and frequrenxyx
CATS - deficient in demethyaltion
PIGS - altred metabolic activity
RUMINANTS - plasmasoudoestrane deficiency.
what consequences can occurs form phase 1/2 reactions/
poor bioavaialbilty, larger does needed, marked inter-indivial variation, species, breed, indiviudal etc
what does the induction of micromomal enzymes do?
some drugs induce synthesis of microsomal enzymes , results in ⬆️ metabolism + increase/decrease toxicity.
what is clearance?
effieceny pf irreversible wlimatoin of a drug form the systematic circulation
OR
volume of blood cleaned of a drug per unit time.
what are OCTs and OATs
organic cation transports and organic anion transports.. passes into the gut and removes more waste products
what is enteroheptic circulation?
gut is able to breakdown molecules, glucoropides hydrolysed and reabsorbed - up to 20% of drug.
describe 0 order kinetics?
Sc/St = k
rare in practice
Describe 1st order kinetics?
Sc/St = kC
most drugs
what is half life?
amount of time taken for a quantity to fall to half it value as measured at start of time period
what is affinity?
a measure of the attraction between drug and receptor
what is Efficacy?
the ability of a ligand, once bound, to elicit a response
what is an agonist?
is a chemical that binds to a receptor and activates the receptor to produce a biological response.
what is an antagonist?
type of ligand or drug that avoids or dampens a biological reaction. Upon binding to the receptor, it does not activate.
what are the Types of antagonism?
completive and non-competitive,
physiological
chemical
pharmacokinetic
what is a single compartment model (Pharmacokinetic)
a single, well-stirred compartment into which a drug is introduced and is well eliminated
what is a two compartment model? (pharmacokinetics)
admin i.v. “central compartment
distribute to “peripheral compartment
extra compartments affect time to drug action NOT steady state
name the parameters used to investigate liver damage?
Hepatocellular enzymes
Billary enzymes.