Introduction to Clinical Toxicology Flashcards
What are some toxin sources?
Pesticides, drugs, chemicals, toxins (bacterial, fungal, plant, animal), feed additives, poisonous gaases
What is toxicology?
Study of poisons
Includes identification, chemical properties, biologic effects, and treatment of conditions
What is poison synonymous with?
Toxin or toxicant
What is a xenobiotic?
Foreign drug or chemical in body (harmful or not)
What is toxicity?
Refers to the amount of poison or potency (mg/kg)
What is dose response?
Greater the dose, the greater the respons
What is threshold dose?
Dose = no detrimental effects measured
Most toxic responses increase in severity with increasing amounts of toxicants
What is a lethal dose?
Potential of drug or chemical to cause death
What is LD50?
The dosage lethal to 50% of animals eposed
What is LC50?
Concentration of xenobiotic in water lethal to 50% of animals exposed
What is the dose-response relationship?
Xenobiotic interacts with molecular receptor site to produce response
Degree of response is correlated to xenobiotic concetration at receptor site
Xenobiotic concentration at receptor site is related to dose received
What is a target organ?
Area of the body most often affected by xenobiotic
What are the routes of toxicant exposure?
Ingestion Cutaneous Inhalation Injection Ocular
What are factors that affect toxicant intake orally?
Weight of exposed animal
Percent body weight of toxicant consumed
Concentration of xenobiotics
What is the average water intake?
2-3 L of water/kg of dry feed consumed
What is 1 ppm equal to?
1 mg/kg
1 μg/g
1 mg/L
How many ppm is a 1% solution?
10,000 ppm
Move decimal 4 places to the right for percent to ppm
What are the 4 events that occur with post-xenobiotic exposure?
Aborption
Distribution within the body
Metabolism
Excretion
What is absorption?
Movement of xenobiotic from site of administration into the blood
What is the rate of xenobiotic diffusion across a membrane proportional to?
Concentration across membrane, lipid/water partition coefficient, and diffusion coefficient
What does toxicant transportation by blood depend on?
Physiochemical properties
Concentration gradient between blood and tissue
Ratio of blood flow to tissue mass
Affinity of xenobiotic for tissue
What is the distribution of toxins associated with?
Site with susceptible receptors where reaction can occur
Inert site without receptors or effect
What is the most metabolically active organ?
Liver
What is the goal of biotransformation?
Make xenobiotic more water soluble
What is the most common route of excretion?
Renal excretion (glomerular filtration or active tubular secretion)
How can diagnostic evaluation help with toxicology?
Determine cause or source of intoxication
Enable specific therapy with specific antidotes/prevention
Protect public health
Determine liability
What does a confirmed toxicology diagnosis test rest upon?
History Clinical signs Lesions Clinical tests Animal tissue samples Environmental samples Chemical analysis Bioassays
True or False: treat the patient, not the poison
True
How can you treat the patient?
Telephone instructions Remove from source Label (amount, toxic ingredients, antidotes) Time of exposure Vomiting Emergency
What are the goals for therapy of an intoxicated patient?
Stabilize vital signs Clinical evaluation Prevent continued exposure Facilitate removal of absorbed toxicant Antidote Supportive therpay
How do you stabilize vital signs?
Ensure patent airway Make sure patient is breathing Prevent aspiration of vomitus Maintain cardiovascular function Control CNS stimulation Control body temperature
When is emergency intervention necessary?
Respiratory depression or failure
Manage cardiac arrhythmias
Shock-sequela to toxicants that cause fluid loss, vomiting, diarrhea, blood loss, or cardiomyopathy
CNS emergency
How can shock-sequela be treated?
Fluids
Blood
Monitor CVP
Blood gas
What is used to treat seizures?
Diazepam
Phenobarbital
Pentobarbital
How do you treat hyperthermia?
Cold baths
Ice packs
Cooled IV fluids
How do you treat hypothermia?
Blankets
Hot water bottles
Heating pads
How can you prevent continued absorption?
Emesis
How much can emesis remove?
60% of ingesta
True or False: emesis is still effective 2-4 hours after ingestion
False
What is emesis not used in? Why?
Rodents, rabbits, horses, or ruminants
They cannot vomit safely or effectively
When is emesis contraindicated?
When an animal is unconscious, depressed, seizuring, or suspect corrosive or caustic volatile materials
What is used when emesis is ineffective or contraindicated?
Gastric lavage
What is the purpose of an endotracheal tube for gastric lavage?
Prevent aspiration of stomach contents
How is lavage fluid administered for gastric lavage?
Gently by gravity flow at 10 ml/kg
What is an enterogastric lavage?
Gastric lavage and retrograde high enema give with the gastric tube and endotracheal tube still in place
How does adsorption with activated charcoal work?
Physical binding of toxicant with charcoal (unabsorbable) eliminated in feces
What is charcoal usually administered with and why?
Cathartic (sodium sulfate orally)
Hastens removal of toxicant-charcoal complex and removes constipation from charcoal
When is gastrotomy, rumenotomy, and endoscopy used?
Refractory cases
Foreign bodies
Toxic oils, tars
What is used in the case of dermal exposure?
Wash with warm water and soap or mild detergent
Clip long haired animals
What is used in the case of icular exposure?
Immediate flush with water or physiological saline
How can you facilitate removal of absorbed toxicant?
Activated charcoal
Diuresis
What do patients often benefit from?
Supportive and symptomatic therapy which offset toxic effects
