Guided Notes: Toxicology
Name:___________________________
Do Now
What are poisons? Are drugs poisons?
Drugs, Poisons, and Toxins
Drug - a substance that when taken into the body produces _________________________________
__________________________________________________________________________________, usually by
interfering with the body’s normal chemical reactions
Poison – a substance that when taken into the body produces _______________________________
__________________________________________________________________________________, usually by
interfering with the body’s normal chemical reactions
Toxin – a ______________________________________ substance that when taken into the body at
_________________________________________________________________________________, usually by
interfering with the body’s normal chemical reactions
How are they similar?
How are they different?
“All substances are poisons. There is none which is not. The right dose differentiates a poison and a remedy”
– Paracelsus 16th c. physician
___________________________________________________________________________________
● Tylenol, multivitamins, codeine, alcohol, etc.
Moreover, ___________________________________________________________________________
____________________________________________________________________________________.
● Arsenic is used to treat certain types of leukemia
● Botulin is used for botox, muscle spasms, crossed eyes, etc
Determining toxicity
There are 5 main things which determine the toxicity (adverse effects) of a poison:
1)
2)
3)
4)
5)
Acute toxicity –
Chronic toxicity –
Synergist –
Antagonist -
Measuring toxicity
The toxicity of substances can be measured in
animal trials
•
The poison is introduced to test
animals at different dosages.
•
The dose of poison that kills half of the
animals exposed within a short time
frame is LD50 (50% leathal dose).
Which substance is most toxic?
Why?
Which substance is most toxic?
Why?
1. Determine the LD50 for each drug.
2. Compare the toxicity of the two
drugs.
Calculating Dose Levels
Tylenol
LD50 rat = 3000 mg/kg
Recommended maximum daily dose for adults: 4000 mg
1) What dose would be fatal for 50% of rats, if an average rat is 300g?
2) How much tylenol would a 150 lb person have to take to equal the LD50 dose (calculated for rats)? (Hint 1 kg =
2.2lb)
3) How many tylenol capsules would a 150 lb person have take to equal the LD50? (Hint 1 capsule = 500 mg)
Caffeine
LD50 rat = 192 mg/kg
1) What dose would be fatal for 50% of rats, if an average rat is 325g?
2) How much caffeine would a 125 lb person have to take to equal the LD50 dose (calculated for rats)? (Hint 1 kg =
2.2lb)
3) How many No-Doz capsules would a 125 lb person have take to equal the LD50? (Hint 1 capsule = 100 mg)
Problems with LD50
Although LD50 trials are still used today, their use has declined over the last 20-30 years. Many people and organizations
criticize LD50 trials both for their cruelty and their effectiveness.
Why might LD50 not be a useful measure of toxicity?