Pharmokinetics

Question 1

what is pharmokinetics?

Answer 1

what the body does to the drug

changes over time of drug and metabolite concentrations within body fluids

Question 2

what is a body compartment?

Answer 2

we can simplify a human and call it compartment, with volume V
we can then calculate the concentration C of an introduced drug of a known quantity C

Question 3

what is the general process of drugs in the body?

Answer 3

absoprtion
distribution
metabolism
excretion

Question 4

what is absorption and distribution?

Answer 4

how much drug reaches th target site per unit time

Question 5

what is metabolism and excretion?

Answer 5

how much drug is removed from target site per unit time

Question 6

what is plasma?

Answer 6

the liquid component of blood and this is how drugs move around the body

Question 7

what are six methods of drug administration?

Answer 7

intravenous
intramuscular/subcutaneous
oral
rectal
inhalation
transdermal

Question 8

what must a drug achieve in order to be absorbed?

Answer 8

the drug must be able to cross membranes

Question 9

what are four methods of membrane crossing of drugs?

Answer 9

diffusion through lipid membrane, diffusion through aqueous pore channels formed by aquaporins, via membrane transporters, or via pinocytosis

Question 10

which factors determine how well a drug can diffuse through a membrane?

Answer 10

lipid soluble drugs cross easist
lipid solubility is determined by ionisation
most drugs can exist in ionised or un-ionised (protonated) forms

Question 11

describe protonated drug forms…

Answer 11

HA

lipid soluble and can therefore easily cross cell membranes

Question 12

describe ionised drug forms…

Answer 12

not lipid soluble and so need specific transport mechanism to cross membranes

Question 13

how do pH and pKa influence ionised state?

Answer 13

when pKa is greater than pH, apirin in protonated HA state

Question 14

what are the functions of the BBB?

Answer 14

regulate movement
exude toxic substances
protect neurons

Question 15

how do drugs cross the BBB?

Answer 15

anything lipid soluble can diffuse through endothelial cells
ion channel exchanges
receptor mediated transport

Question 16

what are three examples of phase 1 metabolic processes?

Answer 16

oxidation
reduction
hydrolysis

Question 17

what are two examples of phase 2 metabolic processes?

Answer 17

synthetic (add something)

attach something to reactive group of derivative

Question 18

what is ‘first pass’ (presystemic) metabolism?

Answer 18

occurs to drugs that are extracted by the liver or gut wall before they can reach systemic circulation
need much greater dose and individual variations

Question 19

what are three excretion pathways in the body?

Answer 19

glomerular filtration
passive reabsorption
active tubular secretion

Question 20

what is drug clearance?

Answer 20

the rate of removal of drug from the bloodstream

Question 21

what are two kinetic models than can be applied to describe drug clearance?

Answer 21

first order kinetics (related to plasma concentration)
zero order kinetics (independent of plasma concnetration, dependent on something other than drug availability, i.e. enzyme availability)

Question 22

what are five factors that affect drug clearance half-life?

Answer 22

type of enzyme
enzyme induction
enzyme inhibition
enzyme competition
metabolic variability between patients