Pharmacokinetics

define pharmacokinetics

what body does to drug

what is the 4 step process

1. absorption

2. distribution

3. metabolism/biotransformation

4. excretion

define absorption

how drug moves from site of administration to blood stream

what effects absorbability (2)

1. blood supply

2. amount of drug

define bioavailability

degree to which a drug is absorbed and becomes available by the general circulation

what are the passive process methods of absorption

1. simple diffusion

2. facilitated diffusion

define passive process

no energy required

define simple diffusion

molecules move from an area of higher concentration to an area of lower concentration across a semi-permeable lipid membrane

define Facilitated diffusion

define active process

requires energy to move against concentration gradient.

what are 2 active processes of absorption

1. Pinocytosis

2. Phagocytosis

factors that affect drug absorption (7)

1. Route of administration

2. Drug solubility (fat vs H20)

3. Size of drug molecule

4. Ionization of drug molecule

5. Formulation of the drug

6. Concentration of the drug

7. Blood supply to the absorptive tissues

why inhaled drugs absorbed so fast

because of Rapid absorption due to large surface area with rich blood supply

which absorbs faster lipid or water soluble

lipid-soluble

which is easier to absorb small or large drug

small

— - — drugs diffuse through cell membranes easier than molecules with a charge

non-ionized

do acidic drugs do better in acidic or basic environments

acidic

which has a faster absorption low or high concentration

high

define distribution

how the drug moves from circulation to target site

what effects distribution (2)

1. health status

2. hydration status

define bioavailability

amount of drug that reaches target site

what happens if a patient is hyperproteinemiac

protiens will absorb more so need more drug

define pharmacodynamics

how much drug takes effect on patient

what happens if a drug is stored in tissues (2)

1. can result in prolonged effect as drug is gradually released

2. can become trapped causing decreased blood circulation

define metabolism/biotransformation

changing drug to a form that can be excreted

define half life

how long it takes to half its concentration in the plasma

define summation

Final response is equal to sum of individual responses

define synergism

Final response to using two or more drugs is greater than the sum of the individual responses

define antagonism

drug binds with another drug target receptor