Toxicology Flashcards
What is safety?
Condition of being secure from threat of danger, harm or injury
What is toxicity?
Ability of an agent to cause injury
What is risk?
Expected frequency of occurrence of an undesirable effect
HCl in sealed container—
What is Hazard?
Likelihood that injury will occur in any given situation
What is a spectrum of toxic dose?
Range of doses that might be toxic
Can be very small or very large
What is a risk assessment?
Toxic versus safe
Risk versus benefit
What are the characteristics of potential toxins?
Acid Corrosive Flammable Etc Can be minor or major or both
What is the standard safety margin?
Zone between the surely effective dose (ED99) and the lowest lethal dose (LD1)
Expressed as a percent of the ED99
SSM= ((LD1/ED99)-1) x 100
What are the classification of toxic reactions?
Effects can be
Desirable or Therapeutic
Undesirable- non deleterious (side effects) or deleterious (toxic effects)
What is the classification of deleterious or toxic effects?
Pharmacological-usually effects are reversible
Pathological- causes tissue changes (hepatic necrosis)
Genotoxic-causes long term effects in genetic components and may be transferred across generations (alkylation of DNA)
Systems toxicity
What is the spectrum of deleterious effects?
Classification of toxic reactions
Parent compound or metabolite(meperidine vs normeperidine)
Photo reactions( skin problems related to iron exposure)
Local vs systemic toxicity
Delayed toxicity
Chemical allergy (ie penicillin)
What are the basic components in management of acute poisoning?
Evaluation of the patient (treat patient, not poison ) Termination of exposure Prevention of absorption Enhanced elimination Supportive care Specific drug antidote therapy
How to decide on administering treatment to prevent absorption of toxic substance?
Procedures used depends on time since ingestion
Existing and predicted toxicity of the ingestant
Availability and efficacy
Contraindications of the procedure
Severity and risk of complications
What are the ways to prevent absorption of a toxic substance?
Emesis Gastric lavage Whole bowel irrigation Chemical adsorption-activated charcoal Chemical inactivation Cathartics
What are the contraindications of emesis?
For syrup amd ipecac administration
Existing or impeding CNS depression
Ingestion of a corrosive or hydrocarbon drug-emergence of chemical pneumonia
Presence of a medical condition exacerbated by vomiting
Not recommended as a treatment
When to use gastric lavage?
In life threatening situations that are not treatable with other means
Absolute contraindications if patient is uncooperative
What are the complication s of activated charcoal?
Vomiting Constipation Pulmonary aspiration Death Has greater efficacy Fewer complications than ipecac or gastric lavage
What are the contraindications of cthartics?
Has been abandoned as a GI decontamination strategy
What are the ways of enhanced elimination?
Urinary excretion
Multi dose activated charcoal
Altered metabolism
Dialysis or extracorporeal removal
What are the 3 main substances that cause heavy metal toxicity?
Mercury
Lead
Arsenic
What are the characteristics of mercury toxicity?
Toxicity effects depend upon form and route of administration
Organic mercury (methyl mercury) can penetrate biological barriers including BBB and causes neurological effects
Inorganic mercury causes gastrointestinal and renal problems
Elemental mercury are found in dental amalgams and causes problems when inhaled and not ingested
Major toxic targets are CNS and kidneys
What are the characteristics of lead toxicity?
Displaces calcium and zinc in a number of important proteins
Absorption is variable
Major targets organs are CNS, liver, kidney and pancreas
Concern about excretion through breast milk causing developmental issues for children
What are the characteristics of arsenic toxicity?
Most source of exposure is through food and water
Toxicity increases from organic arsenicals to arsine gas
Can cross BBB and placental barrier
Major targets organs are CNS, kidney
What are the treatment of heavy metal toxicity with chelation agents?
Dimercaprol- acute poisoning by arsenic and inorganic mercury and severe lead
Succimer-analog of dimercaprol
EDTA
Penicillamine- treatment of copper poisoning (Wilson’s disease)
Deferoxamine- treatment of iron poisoning
