Session 11.1 Pharmocokinetics 3

Question 1

what is elimination

Answer 1

metabolism and excretion of drug…being removed from body (both exogenous and endogenous molecules)

Question 2

where does drug metabolism largely occur

Answer 2

liver

Question 3

how are drugs eliminated

Answer 3

increase ionic charge of drugs to enhance renal elimination…lipophilic drugs diffuse out renal tubules into plasma…now inactivated

Question 4

what is phase 1 metabolism

Answer 4

carried out by cytochrome P450 enzymes which are located on ER which catalyse redox, dealkylation, hydroxylation reactions…increase ionic charge of drug

Question 5

what is phase 2 metabolism

Answer 5

mainly cytosolic enzymes - enhances hydrophilicity by further increase in ionic charge. catalyse sulphation, glucorinadation, glutathione conjugation, methylation, N-acetylation

Question 6

what is the exception that is activated by phase 1 metabolism instead of inactivated by metabolism

Answer 6

codeine to morphine which has a higher affinity for opioid u receptor

Question 7

how does increasing charge in phase 1 and 2 metabolism help

Answer 7

enhances renal elimination

Question 8

if above molecular weight of 300

Answer 8

into gall bladder, if below (which is majority) enter kidney

Question 9

what are some key features of cytochrome p450

Answer 9

include three superfamilies..isoenzymes which metabolise drugs by variable contribution

Question 10

what are some clinical factors which affect drug metabolism

Answer 10

age
sex -eg alcohol metabolism slower in women
general health - Heart Renal Hepatic = decreased functional reserve
other drugs - could inhibit or induce CYP450s
variable expression of CYP450s