Toxicology Flashcards
toxicology referrs to
the detection, effects, properties and regulation of toxic substances
Determinants of toxicity?
DOSE and DURATION OF EXPOSURE (blood plasma levels)
Father of modern toxicology?
paracelsus
Therapeutic index eqn:
TI=LD_50/ED_50
Safer drug has what therapeutic index=
larger TI number
ALD-Average lethal dose is determined from?
estimated from accidental deaths in humans
What is the primary determinant of toxicity?
dose
Clinical management of poisoning:
- Support vital - ACB
- Rule out other differentials- IDENTIFY THE POISON (URINE,BLOOD,GASTRIC CONTENTS)
- Reduce, remove the drug in, from the body (decrease dose or decrease time of exposure)
Clinical management of poisoning - unconscious patient:
- give general antidotes available (insulin/glucose if diabetic shock or hypoglycemic; naloxone for narcotic OD)
- use other drugs to treat seizures, cardiac arrhythmias, and severe agitation
toxidromes: what are they? how related to patient?
TOXILOGIC FINGERPRINT FOR AN OD OR POISONING
known toxicology standards of known adverse events - so comparison of the drug or chemical response of the patient with the known tox standard
Lab tests that can be performed in less than 2 hours:
Urine-immunoassay and TLC
Urine/Blood-HPLC or GCMS
Drug removal via emesis- what to give?
Contraindication
- mechanic - a finger bro
- apomorphine
- syrup of Ipecac
- petroleum hydrocarbon solvent poisoning-chemical pneumonitis
- caustic acid of alkali agent= rupture
- seizing or comatose patient
Gastric lavage is?
stomach pumping
Activated charcoal
- how administered
- how work/
- what for?
- orally in water
- very large surface area allows for binding of organic toxicants = no absorption
- othen induces vomoting too
Cathartics
- what does it do?
- exs?
- promotes rapid movement and elimination of poison through GI tract
- sorbitol, mag citrate, mag sulfate
When to dose activated charcoal?
-for max effect within 30 min of poison ingestion
activated charcoal-interactions:-
effectiveness of other meds decreases with co-administration
for organophos poisoning and want to use a chelator give? give with what other drug?
pralidoxime - give with atropine to block muscarinic effects of PNS
for cyanide poisoning and want o give celator?
MOA?
amyl nitrate, sodium nitrate, and sodium thiosulfate with O2
(Hb forms methemoglobin = methemoglobin+CN= nontoxic
farmer poisoning give?
pralidoxine + atropine (probably organophos poisoning from fertilizer)
toxic dose of cyanide?
2mg/kg = death w/in 10-15 min
Botulinum toxin - give what treatment?
-whats special about botulinum toxin?
- must treat ABCs, lavage, emesis, charcoal, trivalent antitoxin
- Most potent poison known - rapid absorption = prevent Ach release from nerve terminals = respiratory depression
Heavy metal poisoning - give what?
- Chelators (BAL, EDTA, DMSA, DMPS,Ca-EDTA, deferoxamine)
- form complex with heavy metals = inert and renal excretion
BAL is?
british anti-lewisite, dimercaptol - for heavy metal poisoning
Tx for lead poisoning?
DMSA, succimer - smells like shit drug - need to put in food or something
Dosage for children >=12 yo w/ lead poisoning,arsenic, or mercury poisoning?
DMSA, succimer-10mg/kg PO q8h for 5 days
Dosage for children 1-11 yo with lead,arsenic, or mercury poisoning?
DMSA, succimer-10mg/kg PO q8h for 5 days
- give same dose then for q12h for 14 days
- total of 19 day therapy
- put in food or juice
Trivalent antitoxin for botulism A,B,E
- where does it come from?
- how to get?
- indications?
- equine
- from CDC via state and local health departments
- good against botulinum toxins types A B and E -most common types we get
-Another heptavalent antitoxin is available against all types
Trivalent antitoxin for botulism A,B,E
-Dosing:
- single 10ml vial per patient - slow IV infusion
- this antitoxin contains WAYYY mORREE antibodies for the toxin than you probably have in your body so itll be enough
Cyanide antidote
-administration:
- its an antidote kit
1) small inhaled dose of amyl nitrite
2) IV sodium nitrite - oxydize portion of Hb iron from ferrous to ferric state = Hb to methemoglobin
3) sodium thiosulfate - reacts with cyanmethemoglobin to give thiocyanate (and sulfate) + Hb –> thiocyanate is peed out
Treat methanol, ethylene glycol, isopropyl alcohol poisoning?
- Give ehtanol bc it prevents alcohol dehydrogenase from converting bad substances into even more toxic substances that kill you
- can give FOMEPIZOL - inh alcohol dehydrogenase
-can use hemodialysis as adjunct therapy
Methanol in the body is converted into what by what enzyme?
-alcohol dehydrogenase - formaldehyde and formic acid
Fomepizol is for? MOA?
Treat methanol, ethylene glycol, isopropyl alcohol poisoning -
blocks alcohol dehydrogenase
Ethylene glycol in the body is converted into what by what enzyme?
What does the breakdown cause?
- alcohol dehydrogenase
- bunch of crap glycoadehyde… glycoate, glycolic acid, glyxylate
-renal failure
Tx for Ethylene glycol poisoning?
- ehtanol - competitive inh of alcohol dehydrogenase
- fomepizol - block alcohol dehydrogenase
- hemodialysis in symptomatic patints
Carbon monoxide poisoning
- how poison?
- tx?
- 210x greater affinity for Hb than O2 - binds strong = carboxyhemoglobin COHb
- artificial respiration with pure O2 to promote displacement of CO - hyperbaric chamber if symptomatic
Symptoms of CO poisoning - 0-10% COHb=
NONE
Symptoms of CO poisoning - 20-30% COHb=
slight headache
exertional dyspnea
Symptoms of CO poisoning - 30-40% COHb=
throbbing headache
fatigue
dizziness
SOB
Symptoms of CO poisoning - 40-60% COHb=
-severe headahce
-weakness
-dizziness
-confusion
-dimness of vision
(CHERRY RED APPEARANCE)***
Symptoms of CO poisoning - >60% COHb=
convulsions
coma
respiratory collapse
DEATH bro
Warfarin -
- what for?
- adverse symptoms:
- anticoag interferes wtih synthesis coag factors 2, 7,9, 10 c and s (VIT K dependent factors)
- hemoptysis, excessive bruising, bleeding from nose or gums, blood in urine or stool
Overdose of warfarin give?
- receptor competitor therapy
- injection of vitamin K (phytonadione)
- if severe bleeding give pro-thrombin complex or fresh frozen plasma to replace coag factors
Opiates -
- name classes
- what tx? benefit to each?
- heroin, morphine, meperidine…
- receptor competitor theory
1) Naloxone: act at mu, kappa, and delta recptors = block reverse effects- duration of action = 45min - used to save acute OD life
2) Naltrexone: - act at same receptors
- longer duration (24-72 hrs)
- used for withdrawal symptoms in rehab
Methemoglobinemia
- issue with this state?
- how caused?
- tx & MOA?
- cant transport O2 (Ferric=ok, ferrous= not good)
- caused by exposure to various chemicals (nitrites sulfa, drugs, and many others
- Methylene blue- direct chemical reduction of methemoglobin back to hemoglobin
Sympatheticomimetic toxidrome
- what drugs?
- what do you see?
- cocaine, amphets, PCP
- mydriasis (DIALYSIS)
- HTN
- tremor
- hyperthermia
- CNS= hallucination agitation, paranoia
Sedative/hypnotic toxidrome
- what drugs
- what do you see?
- ETOH, barbs, benzos
- coma
- Decrease respiration
- miosis or mydriasis
- hypotension
Opioid Toxidrome
- what drugs?
- what do you see?
- opiates, morphine, codine, propoxyphene, oxycodone, hydrocodone
- CNS - coma or dec consciousness
- respiratory depression
- MIOSIS (PINPOINT)
- opiad triad (hypothermia, hypotension, histamine release)
Anticholinergic toxidrome
- what drugs?
- what do you see?
- anticholinergics and antidepressants
- agitation
- mydriasis
- FEVER, DRY SKIN, FLUSHING, URINARY RETENTION (HOT,DRY, MAD, RED, BLIND)
Cholergic toxidrome
- what drugs?
- what do you see?
- organophosphatese/carbamates and insectisides, nicotine
- miosis (PINPOINT)
- DUMBBELLS (EVERYTHING WET)
tricyclic antidepressant toxidrome
- what drugs?
- what do you see?
- TCAs (amytriptyline, imipramine, desipramine)
- coma, agitation
- mydriasis
- dysrhthmias
- convulsions, hypotension (alpha block)
Salicylate toxidrome
- what drugs?
- what do you see?
- aspirin
- inc or normal RR
- diaphoresis aka sweaty
- tinnitis
- agitation
- alkalosis (early)
- acidosis (late)
- hyperpyrexia
Acid poisoning characteristics
- immediate pain in buccal cavity and esophagus
- less often swallowed than bases
- no esophageal perforation
Base poisoning characteristics
- primary cause of chemical burns
- rapidly penetrating liquefactive necrosis
- primary effects on esophagus and only 20% on stomach
- esophageal damage including perforation
Meperidine OD characteristics:
- mydriasis due to antimuscarinic
- INC IN HR
Opiates OD chacteristics:
- bilateral miosis
- HR and RR depression/arrest
Benzos OD characteristics:
TX?
-rarely fatal unless taken with ETOH or other CNS depressants
give flumazenil!!
Acetaminophen OD characteristics
-TX?
- after depletion of glutathione (important for phase 2 metabolism)= hepatic necrosis and death due to hepatic failure
- give n-acetylcysteine!
Cocaine OD characteristics
-tx?
- cardiac dysrhythmias –>cardiac arrest
- give lidocaine for dysrhythmias but noantidote
dioxin
-signs of exposure?
cloaracne - small yellow comedones on face
