LS5003 TB2

Question 1

what is the dfference between dose and dosage

Answer 1

dose= absolute amount administed (mg)

dosage = relative amount (mg/kg^-1)

Question 2

define ED₅₀

Answer 2

effective dose producing 50% response

Question 3

TD_{50 =}

Answer 3

toxic dose producing 50% response

Question 4

LD_{50 =}

Answer 4

lethal dose producing 50% response

Question 5

describe the concept of therapeutic index (drug therapy) relative to toxicology

Answer 5

the ratio of the toxic (or lethal) dose and the desired response - or, in other words the harmful dose ratio to the effective dose.

Question 6

how is therapeutic index calculated

Answer 6

TD₅₀/ED₅₀

LD₅₀/ED₅₀

Question 7

what does a large ratio (TI) mean?

Answer 7

the greater realative safety.

NB: this is the goal in drug discovery - high TIs are desirable

Question 8

define and explain NOAEL

Answer 8

no obesrved adverse effect level

TB: must get above this threshold to see a toxic effect

Question 9

define and explain LOAEL

Answer 9

lowest observed adverse effect level

NB: need to get above his threshold to see lowest obseved effect level

Question 10

whats ADI and hows is it calculated

Answer 10

• acceptable daily intake
• NOAEL/100

Question 11

why is margin of safety used?

How is margin of safety calculated?

Answer 11

• used to overcome confusion or limitations with TD₅₀
• TD₁ (or LD₁) / ED₉₉

Question 12

the toxic response seen with exposure to more than one substance can be described as wha 4 types?

Answer 12

• additave
• synergistic
• potentiation
• antagonisitic

Question 13

what factors influence responce to toxicant

Answer 13

• dose amount and frequency
• dose duration
• subject variability (natural)
• subject variability (health status)
• route of exposure