TOX S Flashcards
What is the definition of toxicology?
A branch of science that deals with poisons
A broader definition includes the study of the detection, occurrence, properties, effects, and regulation of toxic substances.
What are the two types of duration-dependent toxicity?
- Acute
- Chronic
What is dose-dependent toxicity?
The toxicity of a substance varies with the amount administered.
Give an example of a substance that is hepatotoxic at high doses.
Vinyl chloride
At what dose can aspirin become fatal?
About 0.2 to 0.5 g/kg
Which metals are essential in the diet but toxic at high doses?
- Iron
- Copper
- Magnesium
- Cobalt
- Manganese
- Zinc
What is an example of genetic variation affecting toxicity?
Carbon tetrachloride is harmless to chickens but hepatotoxic to humans.
What factors can influence toxicity in humans?
- Age
- Genetics
- Sex
- Diet
- Physiological condition
- Health status
What does LD50 refer to?
The lethal dose required to kill 50% of a population.
List the potential routes of exposure to toxicants.
- Gastrointestinal tract (GIT)
- Lungs
- Skin
- Intravenous (IV)
- Intraperitoneal (IP)
- Intramuscular (IM)
- Subcutaneous (SC)
What is mechanistic toxicology?
The study of biochemical and molecular mechanisms of toxicity.
Define systemic toxicology.
The study of toxic effects on genetic material, including mutagenesis and carcinogenesis.
What is the focus of analytical toxicology?
Identification and assay of toxic chemicals.
What does clinical toxicology encompass?
Diagnosis and treatment of human poisoning.
Name a class of toxic agents that includes insecticides and herbicides.
Agricultural agents
What is NOEL in toxicology?
No Observed Effect Level; a dose below which no effect is observed.
What is the antidote for acetaminophen toxicity?
N-acetylcysteine (NAC)
How does methanol become toxic?
It is oxidized to formic acid.
What is the consequence of ethylene glycol ingestion?
Renal failure, hypocalcemia, metabolic acidosis, and heart failure.
True or False: Isopropanol can lead to acidemia.
False
What is carbon monoxide’s binding affinity to hemoglobin compared to oxygen?
230 to 270 times greater.
What are common sources of carbon monoxide?
- Automobiles
- Poorly vented furnaces
- Fireplaces
- Wood-burning stoves
What is the management for carbon monoxide poisoning?
Prompt removal from source and administration of 100% oxygen.
What is the primary effect of cyanide on cellular respiration?
Inactivation of cytochrome oxidase.
What can be used as an antidote for cyanide poisoning?
IV Hydroxocobalamin (vit B12a)
What are the symptoms of iron toxicity?
- Nausea
- Vomiting
- Abdominal pain
- Metabolic acidosis
- Hypotension
What is Deferoxamine used for?
It is an iron-specific chelator that binds free iron.
What are common symptoms presented by a patient with iron overdose?
Nausea, vomiting, and abdominal pain
Depending on the amount of elemental iron ingested, the patient may progress to metabolic acidosis, hypotension, and coagulopathy, potentially leading to hepatic failure, multisystem failure, coma, and death.
What is deferoxamine and its role in iron overdose?
An iron-specific chelator that binds free iron, creating ferri-oxamine to be excreted in the urine
What are the main sources of lead exposure?
- Old paint
- Drinking water
- Industrial pollution
- Food
- Contaminated dust
How does lead absorption differ between adults and children?
Adults absorb about 10% of an ingested dose, whereas children absorb about 40%
What are the consequences of lead exposure on the body?
- Impairs new bone formation
- CNS effects like lead encephalopathy
- GIT symptoms like abdominal discomfort, constipation, and diarrhea
- Blood effects like hypochromic, microcytic anemia
What is the apparent blood half-life of lead?
About 1 to 2 months, while its half-life in bone is 20 to 30 years
What are the symptoms of lead encephalopathy?
- Headaches
- Confusion
- Clumsiness
- Insomnia
- Fatigue
- Impaired concentration
- Clonic convulsions and coma
What blood lead levels indicate lead intoxication?
Greater than about 25 μg/dL
What is the first-line treatment for children with blood lead levels greater than 45 μg/dL?
Succimer, orally
What are the effects of organophosphate and carbamate insecticides?
- Inhibit AChE
- Accumulation of ACh leading to:
- Nicotinic effects: mydriasis, fasciculations, muscle weakness, hypertension
- Muscarinic effects: diarrhea, urination, miosis, bradycardia, bronchorrhea, emesis, lacrimation, salivation
What differentiates organophosphates from carbamates?
Organophosphates irreversibly inactivate AChE, while carbamates reversibly bind to AChE
What are common treatments for organophosphate poisoning?
- Atropine
- Pralidoxime (IV or IM)
What are the key components of emergency evaluation in toxicology?
- Assessment of toxicity
- Diagnosis
- Supportive care (ABC – Mental status)
- Specific drugs and antidotes
- Decontamination
- Enhanced elimination
What are emergency measures for amphetamine poisoning?
- Airway - ventilation
- Treat seizures and hyperthermia using benzodiazepines
- Sedatives for hypertension if not effective
- IV vasodilators like phentolamine or nitroprusside
What are the classic symptoms of mercury poisoning?
- Tremor
- Neuropsychiatric disturbances (fatigue, insomnia, memory loss)
- Gingivo-stomatitis
What is the treatment for acute mercury inhalation?
- Emergency and supportive measures
- Specific drugs: oral succimer or oral unithiol to enhance urinary Hg excretion
What is the primary treatment for severe scorpion stings?
- Airway - ventilation - oxygen
- Atropine
- Treat hypertension, tachycardia, and convulsions
What are the common systemic effects of poisonous snake bites?
- Weakness
- Muscle fasciculations
- Perioral and peripheral paresthesia
- Coagulopathy
What is the role of anti-venom in snakebite treatment?
Administer specific antivenom for systemic effects and generalized fasciculations, coagulopathy, and muscle weakness
What is forensic toxicology?
The use of toxicology for the purposes of the law, involving analytical chemistry and courtroom testimony
What are the basic investigations in fatal toxicity cases?
- Collection of information and specimens
- Toxicological analysis
- Data interpretation
What factors influence the choice of analytical methods in forensic toxicology?
- Amount of specimen available
- Nature of the toxicant to test
- Whether to detect parent compound, its metabolites, or both
What is the importance of preservative use in toxicology specimen collection?
To protect specimens against postmortem changes
What are the key factors influencing the decision on analytical methods for toxicant testing?
The amount of specimen available, the nature of the toxicant to test, and whether the detected compound is the parent, its metabolites, or both.
Where are the highest concentrations of a poison typically found?
At the site of administration.
What does a large quantity of drug in the GI tract and liver indicate?
Oral ingestion.
What does the presence of higher concentrations of toxicant in the lungs suggest?
Inhalation.
What is the major organ of toxicant excretion?
Kidney.
Why is urine analysis important in toxicology?
It helps in the excretion of toxicants.
What are non-specific initial tests used for in laboratory analyses?
To detect presence or absence of a particular class of compounds.
What is an example of a colorimetric test?
Detection of phenothiazines.
What analytical technique provides qualitative results through color observation?
Thin-Layer Chromatography (TLC).
What does Gas Chromatography (GC) identify?
The compound based on retention time and detection techniques.
What is the purpose of the Volatile Screen (VS) in toxicology?
To detect ethanol.
What is the Drugs of Abuse Screen (DAS) used for?
Amphetamines, cocaine, marijuana.
What does the General Drug Screen (GDS) assess?
Unclear causes of death.
What is the primary goal of legislation in toxicology?
To prevent toxicity through regulation and control.
What does the Toxic Substances Control Act (TSCA) regulate?
The introduction of chemicals into commerce.
What is ecotoxicology concerned with?
The toxic effects of chemical and physical agents on populations within defined ecosystems.
What are persistent organic pollutants (POPs)?
Chemicals that are poorly degraded and can accumulate in the environment.
What is the main concern with lipophilic substances like organochlorine pesticides?
They tend to bioaccumulate in body fat.
What are the five major substances that account for about 98% of air pollution?
- Carbon monoxide (52%)
- Sulfur oxides (14%)
- Hydrocarbons (14%)
- Nitrogen oxides (14%)
- Ozone (4%)
What is a common source of nitrogen oxides (NO2) in the environment?
Automobile and truck traffic emissions.
What is the primary toxic action of organochlorine pesticides?
CNS stimulation.
What is the main mechanism of toxicity for organophosphorus pesticides?
Inhibition of acetylcholinesterase (AChE).
What is the major toxic effect of carbamate pesticides?
Inhibition of acetylcholinesterase (AChE) but with shorter duration compared to organophosphorus pesticides.
What does the term ‘coma cocktail’ refer to in emergency treatment?
A combination of IV dextrose, Naloxone, and Thiamine.
What is a common method for GI decontamination?
Gastric lavage, activated charcoal, or whole bowel irrigation.
Which substances do not adsorb to activated charcoal?
Lead and other heavy metals, iron, lithium, potassium, alcohols.
What is urinary alkalinization used for in toxicology?
To enhance elimination of salicylates or phenobarbital.
What is the goal urine pH for urinary alkalinization?
7.5 to 8.
What are some examples of medications or substances that can be removed with hemodialysis?
Methanol, ethylene glycol, salicylates, theophylline, phenobarbital, lithium
These substances are typically removed due to their toxicity and the effectiveness of hemodialysis in clearing them from the bloodstream.
What is the goal urine pH for urinary alkalinization?
7.5 to 8
This pH range is critical to ensure effective ion trapping while maintaining serum pH below 7.55.
What intravenous solution is used for urinary alkalinization?
IV sodium bicarbonate
Sodium bicarbonate helps in increasing the urine pH to facilitate the excretion of certain drugs.
What is the purpose of multiple-dose activated charcoal?
Enhances the elimination of certain drugs
This method is effective for drugs like theophylline, phenobarbital, digoxin, carbamazepine, and valproic acid.
How does activated charcoal enhance drug elimination?
By creating a gradient across the lumen of the gut
This gradient promotes the movement of drugs from the bloodstream into the gastrointestinal tract.
What is the effect of activated charcoal on medications undergoing enterohepatic recirculation?
Blocks their reabsorption
This is achieved by adsorbing the substance to the activated charcoal, preventing it from re-entering the systemic circulation.
What must be present before administering each dose of activated charcoal?
Bowel sounds
This ensures that there is movement in the gastrointestinal tract to prevent obstruction during treatment.
True or False: The serum pH should not exceed 7.55 during urinary alkalinization.
True
Maintaining serum pH within this limit is crucial for patient safety and effective treatment.
