Toxicokinetics

Question 1

what is toxicokinetics

Answer 1

study of absorption, distribution, biotransformation and excretion of toxic agents

Question 2

importance of studying toxicokinetics

Answer 2

knowing the routes of exposure

knowing distribution of poison to target organs (site of action) - clinical signs

selection of proper specimens for chemical analysis

knowing sites of storage

elimination and half life - withdrawal/quarantine periods

Question 3

drugs and toxicants are

Answer 3

xenobiotics (foreign chemicals)

Question 4

what is the most common route of exposure in toxicology

Answer 4

oral

Question 5

which cases is dermal route important

Answer 5

insecticides

Question 6

inhalation is important with

Answer 6

toxic gases and insecticides

Question 7

what is lethal synthesis

Answer 7

metabolite is more than the parent compound is important in toxicology

ex: organophosphates and ethylene glycol

Question 8

drug disposition

Answer 8

study of movement of drugs in the body across biological memebranes from time of absorption until elimination

Question 9

stages of drug disposition

Answer 9

absorption

distribution

biotransformation

excretion

Question 10

T/F bulkflow of water can carry with it small water-soluble substances

Answer 10

True

Question 11

factors that effect simple diffusion

Answer 11

concentration gradient

lipid solubilty

degree of ionization (drugs cross biological membranes in nonionized form)

Question 12

rate of diffusion depends on…

Answer 12

the ratio of non ionized to ionized

Question 13

ionization of the drug depends on

Answer 13

pH of drug

pKa of drug

pH of medium (environment)

Question 14

what is the pKa

Answer 14

the pH at which a weak electrolyte is 50% ionized and 50% non ionized

most drugs are weak electrolytes (weak acids/bases)

Question 15

drug absorption

Answer 15

transfer of the drug from site of administration to the circulation

Question 16

factors related to the drug that affect absorption

Answer 16

molecular size

lipid solubility (increases with increased solubiltiy)

degree of ionization

dissolution of drug in water (liquid faster than solid)

concentration of drug

route of administration

Question 17

is anyone else having pharm flashbacks

Answer 17

I mean his notes even say “drug” and not “toxicant”

Question 18

factors related to the animal that effect absorption

Answer 18

blood flow

absorbing surface area

connective tissue

species

individual

Question 19

drug metabolism (biotransformation)

Answer 19

chemical alteration of the drug molecule by the cells of the animal

Question 20

results of biotransformation

Answer 20

change physiochemical properties of the drug (water soluble, polar, ionized etc)

change pharmacological activity (bioinactivation/activation, detoxification, lethal synthesis)

Question 21

sites of biotransformation

Answer 21

liver

other tissues - nervous tissue, kidney, GI

plasma

Question 22

T/F liver enzymes lacl specificity

Answer 22

true

Question 23

T/F enzymatic reactions are saturable and drugs can compete on the same enzyme

Answer 23

True

Question 24

microsomal enzymes cause

Answer 24

oxidation, reduction, hydrolysis and conjugation to glucuronic acid

Question 25

types of metabolic reactions

Answer 25

**phase 1** (oxidation, reduction, hydrolysis) **phase 2**- synthetic (conjugation)

Question 26

factors altering biotransformation

Answer 26

species individual route of administration enzyme inducers enzyme inhibitors liver disease

Question 27

enzyme inducers

Answer 27

drugs that stimulate the liver to produce more metabolic enzymes only microsomal enzymes are inducible by drugs

Question 28

enzyme induction is reversible/irreversible

Answer 28

reversible

Question 29

enzyme induction may lead to

Answer 29

tolerance or drug-drug interactions

Question 30

enzyme inhibitors

Answer 30

drugs that inhibit the liver to produce metabolic enzymes may lead to drug-drug interactions

Question 31

newborns are geriatric patients may have more/less biotransformation than adults

Answer 31

less

Question 32

excretion

Answer 32

removal or clearance of the drug from the body

Question 33

routes of drug excretion

Answer 33

renal hepatic feces milk semen saliva eggs hair/feathers sweat glands expired air

Question 34

methods of renal excretion

Answer 34

glomerular filtration active tubular secretion tubular reabsorption