Gapcom 4/13 Drug Toxicity (X)

Front 1

classification of effects of chemicals

Back 1

desirable - therapeutic
undesirable (non-deleterious side effecs)(deletrious toxic effects - pharmacological, pathological, genotoxic)

Front 2

what are the different exposure periods to a chemical

Back 2

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

Front 3

what can be used to prevent further absorption of poison?

Back 3

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

Front 4

contraindications for emesis

Back 4

corrosive poison ingested, CNS stimulant can overexcite by precipitating vomiting, petroleum distillate can aspirate and cause chemical pneuomonitis)

Front 5

gastric lavage contraindications

Back 5

same as for emesis and possibility of mechanical injury to throat, esophagus, and stomach.

Front 6

enhanced elimination of the poison

Back 6

biotransformation, biliary excretion, urinary excretion

Front 7

techniques used to enhance elimination

Back 7

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

Front 8

give antidotes for below
1. arsenic
2. benzodiazepines
3. carbon monoxide
4. coumatin
5. lead
6. organophosphates

Back 8

antidote
1. BAL (dimercaprol)
2. flumazenil
3. oxygen, hyperbaric O2
4. vitamin K
5. dimercaprol, penicillamine, or succimer
6. atropine (antagonist at Ach receptor), pralidoxime*

Front 9

define toxicology

Back 9

study of toxic or harmful effects of chemicals. also concerned with the symptoms and treatment of poisoning and the identification of the poison

Front 10

list the fields of toxicology

Back 10

1.environmental (e.g. air and water pollution)
2.economic (e.g. food additives and pesticides)
3.legal (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)

Front 11

most important axiom of toxicology

Back 11

the dose makes the poison.
the degree of injury inc as the dose inc

Front 12

define poison

Back 12

a chemical substance that, in relatively small doses, seriously impairs or destroys life

Front 13

distinction btw drug and poison

Back 13

often arbitrary. no drug is so selective in its pharmacotherapeutic action that it produces no undesired (adverse) effects

Front 14

define LD50 or median lethal dose

Back 14

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.

Front 15

define therapeutic index

Back 15

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.

Front 16

what are two caveats to the therapeutic index

Back 16

1. no value in predicting occasional hypersensitive patient.
2. not useful for evaluation of therapeutic effectiveness

Front 17

list several types of animal toxicity tests

Back 17

depends on anticipated clinical use of new drug... irritation, sensitization, neonatal toxicity, teratogenicity, carcinogenicity

Front 18

differentiate mild from toxic adverse drug rxns (ADR)

Back 18

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).

Front 19

differentiate predictable vs. unpredictable drug toxicity in huamsn

Back 19

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.

Front 20

differentiate idiosyncratic reactions and drug allergy (hypersensitivity).

Back 20

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.

Front 21

define iatrogenic disorder.

Back 21

physician induced disorder. failure of physician to prescribe drugs that takes into account all the possible pharmacology and potential toxicity assoc with the drug.

Front 22

in contrast to toxic reactions, allergic reactions...

Back 22

1.are unrelated to dose
2.occur only in susceptible person
3.are the same (NOT related to the pharmacologic classification of the drug)

Front 23

describe chemical adsorption. give ex. of something use in poison case.

Back 23

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.

Front 24

define LD50 or median lethal dose.

Back 24

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.