Toxicology - Mata Flashcards Preview

IDIT Exam 2 - Pharm/Path > Toxicology - Mata > Flashcards

Flashcards in Toxicology - Mata Deck (21)
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1
Q

What is a toxic response?

A

• Change from normal state

o Could be on molecular, cellular, organ or organism level

2
Q

What are the 4 types of toxic response?

A
  1. Local vs systemic
  2. Reversible vs irreversible
  3. Immediate vs delayed
  4. Graded (individual) vs quantal (population)
3
Q

Graded (individual) vs quantal (population) response

A
  • Degrees of the same damage vs. all or none
  • Quantal dose-response is extremely important in toxicology and used to determine the median toxic (TD) or lethal (LD) dose of a substance
4
Q

Dose Response Curve

A

Shows therapeutic index or dose at which 50% of people given drug will have a therapeutic effect

5
Q

ED50

A

Median Effective dose at which 50% of the population responds

6
Q

TD50

A

Median Toxic dose at which 50% of the population responds

7
Q

LD50

A

Median Lethal dose at which 50% of the population responds

8
Q

Therapeutic Index

A

LD50/ED50

9
Q

On Target Adverse Drug Effects - Intended Tissue

A
  • Dose too high

* Chronic activation or inhibition effects

10
Q

On Target Adverse Drug Effects - Unintended Tissue

A
  • Correct receptor, but incorrect tissue
  • Dose too high
  • Chronic activation of inhibition effects
11
Q

Off Target Adverse Drug Effects

A

For both intended and unintended tissues

• Incorrect receptor is activated or inhibited

12
Q

Subtoxic damage

A

In response to moderate or high doses or drug

13
Q

What can you do to intervene?

A
  • Reduce absorption of toxin
  • Reduce or increase metabolism
  • Increase excretion of toxin
  • Neutralize toxic effect
14
Q

GI Decontamination

A

• Activated charcoal
o Effectively absorbs all drugs or toxic chemicals
• Gastric lavage
o Use after ingestion of:
• Sustained release drugs
• Xenobiotics not absorbed by activated charcoal

15
Q

Reducing formation of toxic metabolites

A

Administer agent that alters the production of a toxic metabolite

16
Q

Reducing formation of toxic metabolites - Acetaminophen Example

A

• Metabolized by P450 to a reactive metabolite that induces hepatotoxicity
• Greater risk to chronic alcoholics or patients taking drugs that alter P450
• Mechanism of antidote
o Replenishes glutathione and reacts directly with NAPQI

17
Q

Reducing formation of toxic metabolites - Methanol and ethylene glycol Example

A

• Metabolized to form highly toxic acids
• Mechanism of antidote
o Fomepizole competitively inhibits alcohol dehydrogenase, an enzyme which catalyzes the metabolism of ethanol, ethylene glycol, and methanol to their toxic metabolites

18
Q

Increase renal elimination

A

• Works for weak acids by enhancing increasing urinary pH (ion trapping)
• Antidote
o Sodium bicarbonate (IV)
• Produces urine alkalization (alkaline diuresis)

19
Q

Increase GI elimination

A

• GI excretion can be enhanced by increasing adsorption of toxin into the lumen
• Antidote
o Multiple doses of activated charcoal
• Increases the intestinal diffusion of drug in blood → drug in lumen

20
Q

Neutralizing toxic effects of xenobiotics

A

• Antidote: Antagonists
o Prevent binding of toxins with its target site
o Prevent binding of endogenous chemical with its target site

21
Q

Treatment of drug or chemical toxicity

A

• Antidote: Chemical inactivation
o Bind directly to toxin
• Chelation of heavy metals
o Examples: lead, mercury and iron poisoning
• Antidote: Antitoxin (antibodies to venoms)
o Bind directly to toxic protein from bites of poisonous animals