Toxicology

Question 1

Methotrexate elimination is primarily by…

Answer 1

Renal excretion

Question 2

What happens to cholinesterase activity in the setting of organophosphate poisoning?

Answer 2

Plasma and red cell cholinesterase activity is reduced to <50% with clinical poisoning and <10% in severe cases

Question 3

Sample type(s) that are used for testing exposure to organophosphates

Answer 3

• red cell cholinesterase (mostly aceylcholinesterase)
• plasma cholinesterase (mostly butyrlcholinesterase)

Do not test <1 week of scoline administration or <2 wks transfusion

Question 4

Which enzyme affects therapeutic response to codeine?

Answer 4

CYP2D6

Required to convert Codeine into active metabolite

Question 5

Tacrolimus works by entering lymphocyte, binding to FK-binding protein and blocking …?

Answer 5

Calcineurin

Calcineurin is involved in production of Il-2 and T cell proliferation

Question 6

High concentrations of tacrolimus are associated with risk of … ?

Answer 6

Nephrotoxicity

Question 7

Sample type and preparation for Tacrolimus measurement

Answer 7

Whole blood sample
>90% of tacrolimus is intracellular, needs to be liberated to measure
Samples are mixed with a pretreatment that lyses the cells and precipitates the proteins.
Centrifuge to obtain supernatant containing the drug.