EXAM #5: INTRODUCTION TO TOXICOLOGY Flashcards
What is toxicology?
Subtopic of pharm concentrating on the effects and properties of toxic substances
What does it mean that poisoning if situational and quantitative in nature?
Any substance at the right DOSE and for the right amount of TIME can be a poison
Why do we study toxicology?
1) Protect us from adverse effects of toxicants
2) To develop improved toxicants
What is the definition of the LD50?
Dose at which 50% of animals die
What is the definition of the TI i.e. how do you calculate the TI?
LD50/ED50
What does a big TI indicate?
Safe drug
What is the ALD?
Average Lethal Dose
*Note that this is estimated from accidental deaths in humans
What is the primary determinant of toxicity?
Dose–you want to know:
- How much?
- When?
How do you clinically manage poisoning?
1) Support patient’s vitals:
- ABCs
2) Reduce or remove drug
What are two treatments that can be considered for an “unconscious for unknown reason” type patient?
1) Glucose
2) Naloxone
What is a toxidrome?
Group of signs and symptoms constituting the basis for the diagnosis of poisoning
What are two emesis inducers?
1) Apomorphine
2) Syrup of Ipecac
What are the contraindications to emesis inducers?
- Chemical pneumonitis e.g. WD40
- Acid or alkali agents
What is the MOA of activated charcoal?
Very large SA that binds to toxic agent
When should charcoal be administered?
Within 30 min. or ingestion
What cross reaction do you need to remember about activated charcoal?
Efficacy of other medications will decrease with charcoal administration
What is the antidote to organophosphate poisonin e.g. Sarin, insecticide bomb…etc?
Pralidoxime or 2-PAM
- Binds organophosphate
Atropine= blocks muscarinic effects
What is the MOA of cyanide poisoning?
Deactivation of cytochrome C in mitochondrial membrane
CNS and cardiac tissue most affected
What is the antidote for cyanide poisoning?
Amyl nitrite
Sodium nitrite
Sodium thiosulfate
*All with O2
What is the most potent poison known to man?
Botulinum toxin (prevents ACh release from nerve terminal)
What are BAL, EDTA, DMSA, DMPS, calcium EDTA, and deferoxamine used to treat?
Heavy metal poisoning
What is DMSA specifically indicated for?
Treatment of:
- Arsenic
- Mercury
- Lead poisoning
How is DMSA dosed?
10mg/kg PO for 5x days if OVER 12
- Under 12, add an additional 14 days for 19 total days of treatment
What is the antidote for Botulinsm toxin?
Antibody for Botulism A, B, and E
What is the MOA of the drugs used to treat cyanide poisoning?
1) Oxidize Hb to methemoglobin
2) Binds cyanide to make cyanmethemoglobin
ADD Sodium thiosulfate
3) Cyanmethemoglobin–>thiocyanate and Hb
How can ethylene glycol/methanol/isopropyl alcohol poisoning be treated without an antidote?
Ethanol that will competitively inhibit alcohol dehydrogenase
What is the antidote for ethylene glycol/ methanol/ isopropyl alcohol poisoning?
Fomepizole
What is the MOA of Fomepizole?
Blocks alcohol dehydrogenase from making toxic metabolites
How does the affinity of CO for Hb compare to O2?
CO has 210x greater affinity
What is the treatment for CO poisoning?
Hyperbaric O2
What is the classic appearance of CO poisoning?
Cherry red lips/gums
How does an overdose of Warfarin present?
Excessive bleeding e.g:
- Hemoptysis
- Bruising
- Bleeding from nose or gums
- Blood in the urine/stool
What is the antidote for Warfarin?
Vitamin K
What are the antidotes for opoid overdose? What is the difference?
Naloxone= acute OD b/c of short half-life
Naltrexone= longer duration of action
What is methemoglobinemia?
Heme iron is in the Fe3+ state that cannot bind O2
What is the antidote for methemoglobinemia?
Methylene Blue
What is the MOA of Methylene Blue for Methemoglobinemia?
Direction chemical reduction of methemoglobin back to Hb
List the signs/ sx associated with a sympathomimetic toxidrome.
Mydriasis
HTN
Tremor
Hyperthermia
What are the drugs associated with sympathomimetic toxidromes?
Cocaine
Amphetamines
PCP
List the signs/ sx associated with a sedative/hypnotic toxidrome.
Coma
Decreased respiratory drive
Miosis or mydriasis
Hypotension
What are the common drugs that lead to a sedative/hypnotic toxidrome?
Alcohol
Barbiturates
Benzodiazepines
List the signs/ sx associated with a opiate toxidrome.
Coma
Respiratory depression
Miosis
List the signs/ sx associated with an anticholinergic toxidrome.
CNS agitation
Mydriasis
Fever
Dry skin
Flushing
Urinary retention
Remember, “Hot Dry Red Mad and Blind”
What is the mnemonic to remember the toxidrome associated with Cholinergic agents?
SLUDGE
Salivation Lacrimation Urination Diaphoresis GI Upset Emesis
List the signs/ sx associated with a TCA toxidrome.
Agitation-->coma Mydriasis Dysrhythmia Convulsions Hypotension
List the signs/ sx associated with a salicylate/aspirin toxidrome.
Increased respirations Diaphoresis Tinnitus Agitation Hyperpyrexia
