Introduction to Toxicology

Question 1

Toxin defn

Answer 1

Poisonous substance produced by living cells

Question 2

Examples of toxins

Answer 2

venoms, mycotoxins, microbial toxins, hemlock, marinobufagenin (toad origin), cyanide

Question 3

Toxicant defn

Answer 3

A manmade chemical introduced into the environment that produces toxic effects on living cells

Question 4

Examples of toxicants

Answer 4

Carbon tetrachloride, Phosgene, Dioxin, Sarin, Ethylene glycol, cyanide

Question 5

What are types of toxic responses?

Answer 5

local v systemic
immediate v delayed
reversible v irreversible

Question 6

Local v systemic toxic response

Answer 6

Effect observed at site of contact/portal of entry (poison ivy) vs effect observed at site distant from contact or portal of entry (Bactrim allergic reaction, black widow spider bite)

Question 7

Immediate v delayed toxic response

Answer 7

seconds/hours (peanut allergy, bee sting) vs days/years (diethylstilbestol, lead paint)

Question 8

Reversible v irreversible toxic response

Answer 8

Effect abates after stopping exposure (HR and QT interval changes with anesthetic) vs effect persists after stopping exposure (tetracycline dental staining)

Question 9

Phases of toxic responses

Answer 9

exposure –> disposition –> toxicodynamics

Question 10

What are 3 ways of mitigating toxic responses?

Answer 10

prevent/reduce exposure (exposure) –> enhance elimination from body (disposition) –> block/repair cellular effects (toxicodynamics)

Question 11

What is the therapeutic index?

Answer 11

TI = TD50 (toxic effects in 50% at this dose)/ED50 (effective dose in 50% at this dose); high TI is preferable