Toxicology

Question 1

Name the 3 key forms of toxins

Answer 1

• Chemical irritants eg lead
• Physical enities eg radioactive hazards
• Biohazardous substances eg venom, plant extracts

Question 2

Name 2 people who had an impact on history of toxicology

Answer 2

• Paracelsus- grandfather of toxicology
  
  • Described all substances as poisons,
  • Right dose distinguishes poison from remedy
• Mathieu Orfila- father of modern toxicology
  
  • Founded science of toxicology as known today

Question 3

Key concepts of toxicology

Answer 3

• Distinguishing toxic effect from harmless calls for consideration for:
  
  • Method of exposure
  • Frequency of exposure
  • Duration of exposure
  • Route of entry
  • Concentration
  • Physical form
  • Environmental considerations- degradability, bioaccumulation, biomagnification

Question 4

4 Routes of toxin exposure

Answer 4

• Ingestion
• Inhalation
• Dermal contact
• Injection

Question 5

Absorption of toxins depend on

Answer 5

• Chemical structure
• Site of administration

(Lipids are absorbed across membranes faster than strong acids and bases)

Question 6

Low doses of bioavailable toxin are absorbed according to ___1___ order kinetics

High doses eventually approach max absorption according to ___2___ order kinetics

Answer 6

1 first

2 zero (unaffected by increase in concentration)

Question 7

Where is the rate of distribution of toxins greater in the body, plasma or tissues?

Answer 7

• Plasma
  
  • Extent to which it is distributed in the body is defined by volume of distribution

Question 8

Clearance rate at which a toxin is removed is determined by …

Answer 8

Ratio of elimination rate to its plasma concentration

Question 9

Toxins generally affect targets responsible for _________\

Answer 9

Cell maintenance/ regulation

Those affecting metabolism can result in ATP depletion (necrosis), Ca2+ or overproduction of RNS or ROS

Question 10

What is threshold concentration

Answer 10

Minimum amount required to produce a toxic effect

LD50 - median lethal dose
LC50 - median concentration of lethal dose of airborne toxin

Question 11

Define Therapeutic Index

Answer 11

Quantitative measure of relative safety of drug

Compares amount of drug producing a therapeutic effect to amount that produces toxic effect

Toxic dose
TI = ———————-
Therapeutic dose

Question 12

Recognizing toxicity

Answer 12

• Conduct px history and physical exam
• Evaluate vitals (BP, pulse, respiratory rate, temperature)
• Check pupil response (miosis, mydriasis, nystagmus)
• Check oral cavity for lesions
• Check skin colour, temp, humidity
• Palpatie abdomen-rupe out ileus, listen for bowel sounds consistent with cramping