Toxicology Flashcards
(28 cards)
Antidote for Acetaminophen poisoning?
MOA?
N-aceylcysteine.
• supplies cysteine as a precursor for increased glutathione production, and also reacts directly with, and thereby detoxifies, NAPQI.
Liver transplant
Aspirin Poisoning tx.?
Moderate intoxication
- IV sodium Bicarbonate
Severe intoxication
- Hemodialysis
AMPHETAMINES & OTHER STIMULANTS
Tx.?
- Acidification of urine with ammonium chloride.
- For HTN: phentolamine or nitroprusside.
- For tachyarrhythmias: propranolol or esmolol.
- For seizures: IV benzodiazepines.
- Very high body temperatures: neuromuscular paralysis.
B-BLOCKERS TOXICITY - TREATMENT
- IV Glucagon is a useful antidote.
- Increases cAMP in cardiac cells, but through stimulation of glucagon receptors, not B-receptors
used to raise blood pressure and heart rate, such as B-agonists and atropine, are generally ineffective
The antidote for quinidine-like cardiac toxicity is?
DON’T give what drug to a patient w/ TCA overdose?
hypotension tx?
- sodium bicarbonate.
- Physostigmine
- Norepinephrine
MAOIs-TOXICITY
- Cause severe HTN when taken with?
- Tx?
- when tyramine-containing foods or drugs such as phenylpropanolamine or ephedrine are taken.
TREATMENT
•For hypertension: phentolamine or labetalol
Whats the most toxic combination of drug that can cause serotonin syndrome?
Administration of an irreversible MAOI with a serotonergic agent may result in a serotonin syndrome (the most toxic reported combination).
- Involves excessive selective stimulation of serotonin 5-HT 2A and perhaps 5-HT 1A receptors
SEROTONIN SYNDROME-MANAGEMENT
- Serotonin syndrome has been successfully treated with Cyproheptadine (5HT2 receptor antagonist).
- Rigidity, seizures, and agitation are treated with benzodiazepines.
OPIOIDS TOXICITY Tx?
•Naloxone or nalmefene
THEOPHYLLINE -ACUTE INTOXICATION
Usual manifestations include:
- GI manifestations: Vomiting (sometimes hematemesis), Abdominal pain and Diarrhea.
- Metabolic effects: decreased k+, Po43-, increased/decreased Ca+2, increased Glucose and metabolic acidosis.
- Musculoskeletal: Coarse tremor (results from disturbances in skeletal muscle homeostasis of potassium).
- Neurological: Anxiety.
- Cardiovascular: Tachycardia.
Severe intoxication is characterized by:
1. Seizures:
•The major cause of morbidity and mortality in theophylline intoxication.
2.Hypotension and ventricular arrhythmias:
•Caused primarily by excessive beta-adrenergic stimulation.
•The other major concern, but usually do not cause QT prolongation.
THEOPHYLLINE -CHRONIC INTOXICATION
- Cardiac dysrhythmias are more common following a chronic overdose rather than acute overdose and occur with lower serum concentrations.
- Seizures are more common with acute overdose than with chronic overdose however, in chronic exposures, seizures may develop at lower serum concentrations.
- Chronic theophylline overdose has minimal GI signs or symptoms.
THEOPHYLLINE TOXICITY-MANAGEME
- Tachyarrhythmias and hypotension are best treated with a beta-adrenergic receptors blocker (propranolol or esmolol).
- Theophylline-induced seizures benzodiazepines and barbiturates are the most effective agents.
SULFONYLUREAS & MEGLITINIDES
- MOST common AE?
- Tx?
- Hypoglycemia
- patient with a sulfonylurea overdose and symptomatic hypoglycemia should be treated with both intravenous dextrose and octreotide
- Diazoxide is an alternative to octreotide. It also inhibits insulin release. Octreotide is preferred due to its safety and efficacy.
NEUROLEPTIC MALIGNANT SYNDROME?
- Prefered tx?
•Characterized by hyperthermia (altering the core temperature set point), lead pipe muscle rigidity(Blockade of striatal D2 receptors), metabolic acidosis and confusion.
- Bromocriptine prefered
•Bromocriptine and dantrolene for moderate to severe NMS.
•Dantrolene most beneficial when profound rigidity is present.
•If temperature ≥40°C neuromuscular paralysis and aggressive external cooling should be done.
What toxic chemical is Methanol metabolized to?
Formic acid
- Formic acid can cause severe acidosis, retinal damage and blindness.
METHANOL POISONING - MANAGEMENT
- Ethanol: to saturate alcohol dehydrogenase and reduce production of formic acid.
- Or fomepizole**: inhibitor of alcohol dehydrogenase.
- Bicarbonate to treat metabolic acidosis.
- Hemodialysis.
ORGANOPHOSPHATE INSECTICIDES Tx?
•Atropine in large doses.
Initial management must focus on adequate use of atropine.
•If given before ageing has occurred, pralidoxime (2-PAM) splits the phosphate-enzyme bond and acts as cholinesterase regenerator. Because of its positive charge, it doesn’t enter the CNS: does not reverse central effects.
•For convulsions: diazepam or thiopental.
CARBAMATE INSECTICIDES
- The antidote is atropine.
- Pralidoxime is not recommended because the inhibition is spontaneously reversible and short-lived.
- But if the exact agent is not identified and the patient has significant toxicity, pralidoxime should be given empirically
RONDENTICIDE (WARFARIN) MOA?
- One of the most frequently used rodenticides.
- Vitamin K1 restores the production of clotting factors.
- Vitamin K will not begin to restore clotting factors for 6 or more hours (peak effect 24 hours).
- Therefore, patients with active hemorrhage may require fresh-frozen plasma or fresh whole blood.
CYANIDE-MECHANISM OF TOXICITY?
- Cyanide has a very high affinity for Fe3+.
- It binds to the Fe3+ in the heme of cytochrome a,a3 in mitochondria, and prevents oxygen from serving as the final electron acceptor.
- Cellular respiration is inhibited, resulting in lactic acidosis and cytotoxic hypoxia.
CYANIDE POISONING Tx?
TREATMENT •CYANIDE ANTIDOTE KIT: Amyl nitrite pearls Sodium nitrite Sodium thiosulfate •CYANOKIT®:
treatment is aimed at reversal of such binding by providing a large pool of ferric iron to compete for cyanide.
CHELATORS
- Dimercaprol (BAL): supplied in peanut oil (IM).
- Unithiol: water soluable analog of BAL (IV and oral ).
- Succimer: water soluable analog of BAL (oral).
- Edetate calcium disodium (EDTA).
- Penicillamine.
- Deforoxamine.
ORGANIC LEAD POISONING?
tetraethyl lead or tetramethyl lead antiknock gasoline additives, no longer used.
• readily absorbed through skin and lungs.
•Primary signs occur in the CNS and may include hallucinations, headache, irritability, convulsions and coma.
LEAD POISONING- TREATMENT
1.Supportive management: •For seizures: diazepam. •For cerebral edema: mannitol and dexamethasone. 2. Chelation therapy: •EDTA (given by continuous infusion) •Dimercaprol (given IM), •succimer (given orally) •unithiol.
