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24 Cards in this Set

  • Front
  • Back
classification of effects of chemicals
desirable - therapeutic
undesirable (non-deleterious side effecs)(deletrious toxic effects - pharmacological, pathological, genotoxic)
what are the different exposure periods to a chemical
1. acute - occurs when dose is delivered as single event. visible effects in mins to wks
2. chronic - small quantities over long period of time. months to years.
3. subchronic (subacute) - several wks to months
what can be used to prevent further absorption of poison?
emesis (within 1 hr ingestion, best within 5 min)
ipecac (local irritant acts as emetic)
gastric lavage (tube into stomach, water it - within 60 min)
chemical adsorption
contraindications for emesis
corrosive poison ingested, CNS stimulant can overexcite by precipitating vomiting, petroleum distillate can aspirate and cause chemical pneuomonitis)
gastric lavage contraindications
same as for emesis and possibility of mechanical injury to throat, esophagus, and stomach.
enhanced elimination of the poison
biotransformation, biliary excretion, urinary excretion
techniques used to enhance elimination
1. multiple doses charcoal reduce half-life and inc clearance
2. inc pH of urine enhances the elimination of weak acids
3. hemodialysis and hemoperfusion can be used to remove specific agents from the bloood
give antidotes for below
1. arsenic
2. benzodiazepines
3. carbon monoxide
4. coumatin
5. lead
6. organophosphates
1. BAL (dimercaprol)
2. flumazenil
3. oxygen, hyperbaric O2
4. vitamin K
5. dimercaprol, penicillamine, or succimer
6. atropine (antagonist at Ach receptor), pralidoxime*
define toxicology
study of toxic or harmful effects of chemicals. also concerned with the symptoms and treatment of poisoning and the identification of the poison
list the fields of toxicology
1.environmental (e.g. air and water pollution)
2.economic (e.g. food additives and pesticides) (forensics, regulation of emissions and additives)
4.laboratory (analytical tesing for chemicals)
5.biomedical (toxicities of drugs used to treat dx in humans and animals)
most important axiom of toxicology
the dose makes the poison.
the degree of injury inc as the dose inc
define poison
a chemical substance that, in relatively small doses, seriously impairs or destroys life
distinction btw drug and poison
often arbitrary. no drug is so selective in its pharmacotherapeutic action that it produces no undesired (adverse) effects
define LD50 or median lethal dose
a dose (usu single administration) which kills 50% of an experimental animal popn within a specified time after administration (generally 24 hours). determined experimentally by administering progessively larger doses to groups of animals. mortality plotted as a fxn of dosage; LD50 found by interpolation.
define therapeutic index
ratio btw LD50 (MLD) and the ED50 (median effective dose). =LD50/ED50. In general, the larger the ratio, the greater the margin of safety. As determined by lab animals,provides the initial estimation of relative safety of a drug whuch can be used in humans.
what are two caveats to the therapeutic index
1. no value in predicting occasional hypersensitive patient.
2. not useful for evaluation of therapeutic effectiveness
list several types of animal toxicity tests
depends on anticipated clinical use of new drug... irritation, sensitization, neonatal toxicity, teratogenicity, carcinogenicity
differentiate mild from toxic adverse drug rxns (ADR)
mild - non-threatnening to life. annyoing, possibly to point of discontinuing drug. toxic - undesired drug effect which can produce severe effects. also potentially fatal. (eg hepatotoxicity from antiseizure med valproic acid).
differentiate predictable vs. unpredictable drug toxicity in huamsn
1. some ADR are predictable extensions of major pharmacologic actions of drugs (electrolyte and water depletion during diuretic therapy; hemorrhage during anticoagulant therapy)
2. other ADRs (headaches, skin rash, pruritis) are largely unpredictable. they are unexpected. proper drug and dosage selections are necessary to obtain an optimum therapeutic response with minimum ADR.
differentiate idiosyncratic reactions and drug allergy (hypersensitivity).
1. abnormal reactivity to a chemical that is peculiar to any given individual. could be over sensitive to low doses, or have no rxn to high doses. could be caused by genetic polymorphisms in pharmacodynamic factors.
2. hypersensitivity is an allergic rxn to a drug occur bc patient has been exposed previously and the drug has functioned as an antigen.
define iatrogenic disorder.
physician induced disorder. failure of physician to prescribe drugs that takes into account all the possible pharmacology and potential toxicity assoc with the drug.
in contrast to toxic reactions, allergic reactions...
1.are unrelated to dose
2.occur only in susceptible person
3.are the same (NOT related to the pharmacologic classification of the drug)
describe chemical adsorption. give ex. of something use in poison case.
adsorption of a substance is its concentration on a particular surface. activated charcoal adsorbs drugs (alcohols, hydrocarbons, metals and corrosives are not well adsorbed). presence of this in intestine may interrupt enterohepatic circulation of a toxicant, thus enhancing its excretion.
define LD50 or median lethal dose.
dose (usu single administration) which kills 50% of an experimental animal population within a specified time after administration (generally w/in 24hrs). Mortality plotted as function of dosage; LD50 found by interpolation in animal models.