Lecture 35: Toxicology Flashcards
What is Toxicology?
- Focus on toxic effects in patients by unintentional or intentional overdoses
~77% are unintentional
What are some of the Top Medications Overdose in Adults?
- Analgescis [11.2%]
- Sedatives/Hypnoyics/Anti-Psychotics [9.8%]
- Antidepressants [7.2%]
- Cardio Drugs [6.4%]
- Alcohols [4.8%]
What are some of the Top Medications Overdoses in Children?
- Analgesics [9.2%]
- Antihistamines [4.7%]
- Vitamins [4.3%]
What are some of the first things to consider when helping a potentail overdose patient?
Stabilization? Exposure? Assessment?
- Stabilization: ABC management, Vitals, IV access, Oxygenation
- Exposure: What drugs, How much, When taken
- Assessment: Exams/Labs, APAP/Salicylate Tests, Andtidotes?
What is the Anion Gap & Osmolar Gap?
Calculations?
- Anion Gap: difference of Cations and Anions [(Na+K)-(Cl+HCO3)] should be < 14
- Osmolar Gap: Gap = Measured - Calculated [Calculated = (2xNa)+(BUN/2.8)+(Glu/18)+(EtOH/4.6)] should be < 10
What is the importacne of Activated Charcoal?
- Best used in 2-4 hours [44-95% prevention]
- Hard to take; bad taste and gritty
- 1-2g/kg ABW
What are some of the Signs and Symptoms of Opioid Toxicity?
- Respiratory Depression
- Pinpoint Pupils
- N/V
- Drowsiness
- Bradycardia
- Hypotension
What is the General Managment of Opioid Toxicity?
Stabilization? Exposure? Assessment?
- Stabilization: ABC Management [NEED TO DO], CNS/Respiratory Management
- Exposure: What Drug, How much, When?
- Assessment: Labs/Exams, APAP/Salicylate Test, Naloxone
What is the Treatment of Choice for Opioid Toxicity?
- NALOXONE 0.4 - 2mg IV push, IM, IN
- Want to give the smallest amount to AVOID withdrawal
- HIGHER doses for those with illicit drugs use
What are some of the Risk Factors for Acetaminophen Toxicity?
Dose? Conditions?
- Toxic Dose = 7.5-15g
- Risk Conditions: Those taking 2E1 Inducers & Alcohol
What is the Pharmacology of Acetaminophen?
- 60%: Glucaronidation
- 30%: Sulfation [more protective in kids]
- ~10%: 2E1 = necrosis
What is the overall Timeline for Acetaminophen Toxicity?
- 0-24h: no real symtpoms
- 24-48h: Liver issues begin
- 48-72h: More liver issues & increased bilirubin
- 72-96h: Highest liver issues then Hepatic Encephalopathy, Renal Failure, Death
What is the Treatment Options for Aceteminophen Toxicity?
MOA? When to start? Duration?
- N-Acetylcysteine [NAC]
- MOA: Glutathione Surrogate that pushes more toward Glucoronidation pathway
- Best to start withinn 8 hours
- IV = 21h & PO = 72h
- Rumack-Matthew [above line = GIVE NAC & below line = HOLD NAC]
What is the Dosing Regimen for N-Acetylcystine?
IV? PO?
- IV: Loading Dose [150mg/kg IV over 1h] –> Second Dose [50mg/kg IV over 4h] –> Third Dose [100mg/kg IV over 16h]
- PO: Loading Dose [140mg/kg] –> Maintenance Dose [70mg/kg PO q4h for 17 doses]
What are some of the Risk Factors for Salicylate Toxicity?
Disorders? Concentraions?
- Disorders: Mixed Acid/Base = Increased Anion Gap [metabolic acidosis] & Hyperventilation [Respiratory Alkalosis]
- Concentrations: Mild Toxicity = >30 [tinnitus, diszziness] & Severe Toxicity = > 80 [CNS effects]
What are some of the Signs and Symptoms of Salicylate Toxicity?
- Tinnitus & Vertigo
- Seizure
- N/V
- Lethargy/Coma
- Decreased GI Motility
- Altered Mental Status
What is the General Managment of Sakicylate Toxicity?
Stabilization? Exposure? Assessment?
- Stabilization: ABC, IV, Vitals, Oxygen
- Exposure: When, How Much, What Drug
- Assessment: Exams/Labs, Sodium Bicarb
What is the Treatment of Choice for Salicylates Toxicity?
MOA? Monitoring?
- Sodium Bicarb 1-2mEq/kg IV push over 1-2mins
- MOA: Urine Alkalinization
- For Salicylate Conc. > 30, Anion Gap Acidosis, Altered Mental
- Monitor pH & Electrolytes
What are some of the Signs and Symptoms of Sedative Toxicity?
- CNS Depression
- Respiratory Depression
- Bradycardia
- Hypotension
What is the General Managment of Sedative Toxicity?
- Stabilization: ABC, IV, Vitals, Oxygen
- Exposure: When, How Much, What Drug
- Assessment: Exams/Labs, Flumazenil?
What is the Treatment of Choice for Sedative Toxicity?
MOA? Side Effects? Is it really used?
- Flumazenil 0.2mg IV push
- MOA: competing with BZDs at the GABA site [complete inhibitor]
- Can cause withdrawal symtpoms [causes seizures]
- NOT RECOMMENDED because of its FULL INHIBITION of GABA
What are some of the Indications and ** Examples** of TCAs?
- Indications: Bed wetting, Depression, Insomnia, Mirgraines, Neruopathy
- Examples: Amitriptyline, Nortiptyline, Doxepin…
What are some of the signs and symptoms for TCA Toxicity?
- Prolonged QRS
- Anticholinergic Symptoms
- Seizures
- Altered Mental Status
- Hypotension
- Tachycardia
Antichoinergic: Blind as a Bat, Hot as Hades, Red as a Beat, Dry as a Desert, Mad as a Hatter
What are some of the effects of the QRS Prolongations within TCA use?
- > 100 msec = increase seizure risk
- > 150 msec = increased cardiac arrhythmias
What is the treatment for TCA Toxicity?
MOA? Indications? Monitoring?
- Sodium Bicarb 1-2 mEq/kg IV push over 1-2 mins
- MOA: Increase sodium gradient
- Indications: QRS > 100, Arrhythmias, Acidosis
- Monitoring: pH 7.45-7.55; QRS < 100, Stable
What are some of the Examples of some of the Antipsychotics?
Pharmacology?
- Typical: Haloperidol, Fluphenazine, Chlorpromazine, Thioridazine, Perphanazine
- Atypical: Aripiprazole, Clozapine, Olanzapine, Paliperidone, Ziprasidone
1st gen: D2 antagonism
2nd gn: Serotonin/D2 antagonis
What are some of the Signs and Symptoms of Antipsychotic Toxicity?
- Hypotension
- Tachycardia
- QT/QRS Prolongation
- EPS
- NMS
- Sedation
What is important to know about Atypical Antipsychotics Toxicity?
- NOT defined
- Symptoms within 1-2h
- Peak symptoms within 4-6h
- Duration is 12-48h
What are some of the important things to note about NMS Complications?
Treatment?
- High Fever [108] with very stiff muscles; happens in 3-9d –> Death can happen
- Mainly caused by Haloperidol, Depot Fluphenazine or Chlorpromazine
- DC agent; cooling; Benzos;
What is the differences between Serotonin Syndrome and NMS?
- Serotonin Syndrome: Lower Fever; Lasts < 24h; Lower Limbs; Cyproheptadine
- NMS: Higher Fever; Lasts > 24h; Stiff Muscles; Bromocriptine
What is the cause for Digoxin Toxicity?
- Dig blocks Na/K ATPase causing more K to be outside = toxicity
What are some of the Signs and Symptoms of Digoxin Toxicity?
Non-Cardiac? Cardiac?
- Cardiac: Bradycardia, Heart Blocks, Arrhythmias, Hyperkalemia
- Non-cardiac: N/V, Ab Pain, Norexia, Confusion, Vision Changes
What is the General Management for Digoxin Toxicity?
- DC Digoxin
- ABC, Vitals, ECG
- Activated Charcaol: within 2 hours
- Digibind
- Hemodialysis NOT Effective
What is the Treatment that is used for Digoxin Toxicity?
MOA? Indications?
- Digibind
- MOA: Binds to free dig in the body
- Indications: NOT Responsive to Atropine, Hyperkalemia, Ingested > 10mg in adults & > 4mg in kids
What is important to know about the Dosing for Digibind in Digoxin Toxicity?
- Based on the 0.5mg vials
- Acute Ingestion: (mg of dig x 0.8) / 0.5mg
- Serum Dig: (Dig Conc. x Weight [kg]) / 100
Tells how many Digibind vials we have to give
What are some of the Signs and Symptoms for CCB and BB Toxicity?
What do they have in common?
- CCBs: HYPERglycemia, Metabolic Acidosis, Ileus…
- BBs: HYPOglycemia, Bronchospams
- BOTH: Hypotension, Bradycardia, Arrhythmias, Cardiogenic Shock, CNS Depression
What is the General Management for CCB and BB Toxicity?
Potential Antidotes?
- ABC, Vitals, ECG
- Activated Charcoal [depends on time and amount]
- Potential Antidotes: Atropine, Calcium, Vasopressors, Glucagon, High Dose Insulin, Lipid Emulsion
What is the MOA for Atropine in CCB and BB Toxicity?
Effective?
- MOA: Blocks Parasympathetic activity to increase the heart rate
- 0.5-1mg IV push
- NOT ALWAYS EFFECTIVE
What is the MOA of Calcium in CCB and BB Toxicity?
Effective? Dosing?
- MOA: Promotes Ca release = contractility
- Dosing: Ca Cloride is 3x more better than Ca Gluconate
- MORE effective in CCB than BB overdose
What is important about Vasopressor Therpay in CCB and BB Toxicity?
- Higher doses are used
- Vasodilatory Shock = Norepinephrine
- Cardiogenic Shock = Epinephrine
What is the MOA of Glucagon in CCB and BB Toxicity?
Dosing?
- MOA: Causes contractility by hitting Gs to activate ATP to cAMP
- Dosing: HIGHER than in diabetes [3-10mg IV in adults]
- Pre-medicate with Ondasetron to decrease N/V
What is the MOA for High Dose Insulin in CCB and BB Toxicity?
Monitoring? Dosing?
- MOA: Increases inotropy
- Dosing: titrate to systolic BP > 90-100
- Monitoring: Improved Contractility within 15-60mins, Glu = 100-250, Check Electrolytes
When can Iron Toxicity occur within someone?
- 10 - 60 mg/kg of elemental iron
What are the phases of Iron Toxicity?
- 0.5 - 2h: GI upset, ab pain
- 6 - 24h: Recovery? should monitor
- 2 - 24h: shock stage [acidosis, hypotension, poor CO]
- 48 - 96h: Hepatoxicity
- Days - Weeks: GI Scarring, Obstructions…
What is the General Managment of Iron Toxicity?
- ABC, Vital, Fluids
- Activated Charcoal NOT good
- Whole Bowel Irrigation
- Deferoxamine?
What is the Treatment for Whole Bowel Irrigation in Iron Toxicity?
- Polyethylene Glycol
- Takes 4 - 6h to work; should be by a toilet
What is the Antidote Treatment for Iron Toxicity?
MOA? Indications?
- Deferoxamine
- MOA: Chelates iron and enhances renal elimination
- Indicated: Metabolic Acidosis, Iron Tabs in KUB, Conc. > 500
15mg/kg/hour
What are some of the Toxic Alcohols that are can cause Toxicity?
- Ethylene glycol [antifreeze], Methanol [washer fluid, paint remover], Isopropyl Alcohol [rubbing alcohol, paint remover]
What are some of the Clinical Presentations assoicated with Toxic Alcohols and what are the results?
- Anion Gap & Osmolar gap
- Anion gap + Osmolar gap = Methanol; Ethylene
- Osmolar Gap NO Anion Gap = Isopropyl
What are the Phases of Toxicity for Alcohol Toxicity?
- 30 min - 12 h: CNS, N/V, Inebriation, Lethargy
- 12 - 24h: Metabolic Effects, Cardio issues, Anion Gap
- 2 - 3d: Renal issues, Crystals
What is the General Managment of Ethylene Gylcol and Methanol Toxicity?
Treatment?
- Non-Pharm: Gastric Lavage or Aspirations when < 1h; Charcoal NOT good
- Pharm: Ethanol & Fomepizole –> inhibits alcohol dehydrogenase limiting toxic Metabolites
What is Fomepizole?
- Helps with Ethylene and Methanol toxicity
- NO CNS depression & ICU not required
What is the Treatment of Isopropyl Toxicity?
- Hydration
- Hemodialysis