L5- Toxicology Flashcards Preview

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Flashcards in L5- Toxicology Deck (26):
1

What is Vd?

Volume of Distribution is a proportionality term for the apparent volume into which a drug distributes (=L/kg)

= Dose (mg)/ Concentration

Ex. Low Vd = drug resides mainly in plasma and does not readily cross membranes (1 l/kg)

2

What are the Toxicokinetic Principles of Elimination and how are they different in overdose?

Zero Order Elimination vs First Order Elimination Kinetics (Half-Lives)

In an Overdose - people ingest way too much of something and see SATURABLE ELIMINATION KINETICS (Michaelis Menton Kinetics) where elimination of drug switches from First Order to Zero Order and can no longer think of Half-lives

3

Half-Life vs Duration of Action?

Half-life is how concentration of drug decreases over time

Duration of Action is how long drug activates receptor and effector proteins and measurable effects

Ex. Warfarin has half life 35 hours but duration of action is 5 days!

4

What are the generalizations about Pediatric Poisonings?

usually only ingest 1 substance

Low Mortality

Usually a single and Acute ingestion with a short discovery time

5

What are the 1 Pill Killers in Pediatric Populations?

Clonidine - anti-hypertensive med

Sulfonylureas Bupropion, Calcium channel blockers, opioids, chloroquine

Other killers - Heparin, Hydrocarbons

6

What are the generalizations about poisonings in Adults?

more likely to be intentional suicide or abuse

more likely to be mixed substances with multiple causes and from drugs used for non-medically indicated uses

Can be acute or chronic Delay between ingestion and medical care

HIGHER morbidity and Mortality

Inaccuracy in History reporting

Most common analgesics, sedatives, antipsychotics, cleaning products, anti-depressants

7

What is the Sympathomimetic Toxidrome?

Increased HR, BP, RR, Temperature

Dilated Pupils

Sweaty - diaphoretic

Agitated

Causes: Cocaine and Amphetamines

8

What is the Anticholinergic Toxidrome?

Increased HR, BP, RR (or normal), Temperature

Dilated Pupils

Agitated, Confused, Sedated, Hallucinating

DIFFERENCE FROM SYMPATHOMIMETIC IS DRY!!!! NOT SWEATY!!!

Flushed skin and pinkish but not sweating

No bowel sounds, urinary retention, clear chest sounds

Causes: Atropine, Scopolamine, Anti-histamines

9

What is the Opioid toxidrome?

Decreased HR, BP

RR WAY DOWN

Normal temperature

Constricted Pupils and Disconjugate gaze

No change in skin

Lethargic and sleepy almost comatose

Decreased bowel sounds, Urinary retention

Causes: Morphine, Codeine, Oxy, Hydro, Fentanyl

10

What is the Cholinergic Toxidrome?

Decreased HR, BP INCREASED RR!!!!!

Decreased Temperature

Constricted Pupils

Lethargy and Sedation

SWEATTY!!! SLUDGE!!!!! Increased bowel sounds and Dumbels!

Causes: OP, Carbamate, Pesticides, Nerve agents and drugs that stop AchE

11

What happens in Acetaminophen Toxicity?

Tylenol can get metabolized by Sulfonation or Glucuronidation but also can be changed by Cytochrome P450 2E1 to NAPQI which mixes with macromolecules and causes Hepatocellular apoptosis!!!!!

Antidote = Acetylcysteine to replenish glutathione levels to get NAPQI away from hepatocytes

12

What is Anion Gap?

Differences between Cations and Anions in the blood

AG = [Na + K] - [Cl + HCO3] AG >15 is bad and caused by MUDPILES

13

What causes Anion Gaps?

AG >15 = MUDPILES:

Methanol (windshield washer fluid)

Uremia

DKA

Paraldehyde, Phonoformin

Iron, Isoniazid

Lactic Acid

Ethylene Glycol (Antifreeze)

Salycylates!

14

Ways to Prevent Absorption in the Poisoned Patient?

1) Ipecac

2) Gastric Lavage - only if administered within 1 hour of ingestions!!!

3) Activated Charcoal - most effective and causes ADsorption

4) Whole Bowel Irrgation

15

What can you NOT use Activated Charcoal for?

Hydrocarbons like Lamp oil, Kerosene, furniture polish

Alcohols like Ethanol, Methanol, Ethylene Glycol

Metals like Iron, Lead, Arsenic, Mercury

16

What do you use WBI for?

indicated for sustained release preparations, metals or foreign bodies mostly used for metal ingestions

17

What are ways to enhance elimination in the poisoned patient?

1) Multiple Dose Activated Charcoal - used for Enterohepatic recycling (drugs like Theophylline)

2) Urine Alkanization - ion trapping used for Salicylates and Phenobarbital

3) Extracorporeal Drug Removal like hemodyalysis or hemofiltration used for small mlcls with low protein binding and small Vd that are water soluble - Salicylates, Lithium, Toxic Alcohols

18

Antidote for Opioid OD?

Naloxone

19

Antidote for Acetaminophen OD?

Acetylcysteine

20

Antidote for Digoxin OD?

Digoxin Fab

21

Antidote for Snake bite?

Crotalidae Fab

22

Antidote for Sulfonylurea

Octreotide

23

Antidote for Ethylene Glycol or Methanol?

Fomepizole

24

Antidote for Anticholinergics?

Physostigmine

25

Antidote for OP or Carbamate?

Atropine/ Pralidoxime

26

Antidote for Lead, Arsenic, Mercury?

DMSA, BAL, CaNaEDTA, Penillamine