Kinetics and dynamics

Question 1

what is pharmacokinetics

Answer 1

• how the body handles the drug

- how the drug moves within the body

Question 2

what are the four processes of pharmacokinetics

Answer 2

• absorption (in the stomach and duodenum)
• distribution
• metabolism
• excretion

Question 3

what is absorption

Answer 3

• first step in drug transport
• movement of drug from site of administration across one or more body membranes
• drug is transferred from the formulation into the blood

Question 4

what types of factors can help increase the rate of absorption/distribution

Answer 4

• injection
• liquids (faster than solids)
• gas (faster than liquids)
• smaller
• hotter
• empty stomach (less competition = fast absorption)
• more soluble will make it faster

Question 5

what is distribution

Answer 5

• process by which drugs are transported after absorption or direct administration into blood

Question 6

what are some factors that affect distribution

Answer 6

• plasma proteins
• bioavailability
• anatomical barriers; how well the drug passes through these barriers is the one factor that determines its ultimate effectiveness

Question 7

what is metabolism

Answer 7

• the sum total of all chemical reactions in the body
• drug is transformed by body processes
• biotransformation

Question 8

what is the primary site of metabolism

Answer 8

• the liver

Question 9

what is the function of metabolism

Answer 9

• deactivate most drugs
• prodrugs more active after metabolism
• first pass effect via hepatic portal circulation

Question 10

what is the first pass effect

Answer 10

• drugs given orally are absorbed through the intestinal wall and enter the hepatic portal circulation where they are taken directly to the liver for metabolism before reaching the heart and circulating throughout the rest of the body

Question 11

what are some factors that affect metabolism

Answer 11

• differing metabolic enzyme function
• age
• kidney disease
• liver disease
• genetics/race
• other medications and foods

Question 12

what is excretion

Answer 12

• the removal of substances from the body

- via kidneys, respiratory tract, bile or glands

Question 13

what is the primary organ involved with excretion

Answer 13

• the kidney (removes all unnatural and harmful agents in the blood while maintaining balance of natural substances)

Question 14

what is the rate of elimination

Answer 14

• amount of drug removed per unit of time
• determines how long the drug remains in the bloodstream
• determines how long the drug will produce its effect

Question 15

what is half life

Answer 15

• t 1/2
• the length of time for a drug to decrease concentration in the blood by half
• how long the drug will produce its effect
• increased in renal or hepatic diseases

Question 16

what are some factors that influence the effectiveness of drug therapy

Answer 16

• concentration of drug
• frequency of dosing
• food-drug interactions
• drug-drug interactions
• absorption rate
• metabolic rate
• genetics
• excretion rate
• half-life
• changing medical condition

Question 17

what are some hepatic diseases that may affect drugs

Answer 17

• cirrhosis: tends to decrease hepatic metabolism of drugs
• acute viral hepatitis: decreases metabolism in about half of drugs
• obstructive jaundice: appears to diminish elimination

Question 18

how do circulatory diseases affect drugs

Answer 18

• diminished blood flow from a circulatory disorder -> erratic or decreased action in one or more stage of absorption, metabolism, distribution and elimination

Question 19

how do renal diseases affect drugs

Answer 19

• kidney function decrease -> reduced excretion -> drugs accumulate in the blood -> reduced dosages

Question 20

how does hypothyroidism affect drugs

Answer 20

• increases the bioavailability of some drugs

- activity of metabolizing enzymes in the liver is reduced

Question 21

how does hyperthyroidism affect drugs

Answer 21

• decreases bioavailability
• activity of metabolizing enzymes in the liver increased
• increased metabolism of drugs

Question 22

what is pharmacodynamics

Answer 22

• how the body responds to the drug
• how the drug exerts its effects
• mechanism of action (MOA)

Question 23

what is the receptor theory

Answer 23

• cellular mechanism by which most drugs produce effects

Question 24

what is a receptor

Answer 24

• structural component of a cell to which a drug binds in dose related manner in order to produce a response
• lock and key attachment

Question 25

what is an agonist

Answer 25

- induce response - specific drug binds to specific receptor to produce response - give drug a place to bind more easily

Question 26

what is an antagonist

Answer 26

- inhibits or blocks the response of agonists - fit receptor but cannot unlock or activate receptor to produce effect (wrong key in the lock) - occupy the receptor site and block other body chemicals or other drugs from activating the receptor - NOTE: some drugs = master key to unlock several different types of receptors

Question 27

what is the dose-response relationship

Answer 27

- as the dose of the drug increases a maximal response or plateau is reached. increasing the drug produces no additional therapeutic response

Question 28

what is potency

Answer 28

- the drugs strength at certain concentration

Question 29

what happens as we increase potency (see diagram in slideshow)

Answer 29

- more intense effect than same dose of similar drug | - smaller dose needed to produce same effect as another drug

Question 30

what is efficacy

Answer 30

- ability of a drug to produce a more intense response as concentration increased - magnitude of maximal response comparable to another drug - high efficacy = high response