Pharmacokinetics

Front 1

Concentration of drug at site of action is dependent on several variables

Front 2

Pharmacodynamics

Back 2

Relationships between concentrations of drug and effect (what Drug does to Body)

Front 3

Pharmacokinetics

Back 3

Drug absorption, distribution, metabolism, and elimination (what the Body does to the Drug)... A.D.M.E.

Front 4

Enteral Modes of Administration (Entering Intestine)

Back 4

Oral, Sublingual, Rectal

Front 5

Oral Admin (PO) Advantages

Back 5

convenient, safe, economical

Front 6

PO disadvantages

Back 6

GI irritation, destruction of drugs by digestive NZMs, irregular absorption due to food or pH, compliance necessity, 1st pass effect

Front 7

First Pass Effect

Back 7

due to liver metabolism of drug that occurs with oral or rectal admin. prior to drug entering circulation

Front 8

Sublingual advantages

Back 8

avoids 1st pass via superior vena cava

Front 9

Rectal advantages

Back 9

can be used avoid vomiting and some of 1st pass effect

Front 10

Rectal Disadvantages

Back 10

irregular absorption

Front 11

Parenteral Injection modes

Back 11

IV, SQ, IM- outside intestine

Front 12

IV advantages

Back 12

instant and accurate admin, can titrate drug efx, can give otherwise irritating solutions

Front 13

IV disadvantages

Back 13

Danger of toxicity from instant delivery, loss of patent veins

Front 14

SQ advantages

Back 14

slow and constant absorption provides sustained effect, can manipulate for slow absoprtion and/or release (i.e. via co- vasoconstrictor or inserting pellet form)

Front 15

SQ disadvantages

Back 15

cannot use irritating drugs because causes necrotic tissue

Front 16

IM advantages

Back 16

rapid absorption of drugs in aqueous solution, slow but constant absorption of drugs in oil solutions... but can be painful

Front 17

Bioavailable dose

Back 17

how much of a drug will be absorbed and reach circulation. Expressed as % and takes A.D.M.E into account.

Front 18

Factors affecting bioavailability

Back 18

Route of Admin., charge, lipid solubility and size of drug, and patient physiology

Front 19

Properties of Diffusion

Back 19

Not saturable dependent on lipid solubility, only small charged molecules can cross, pH can have a major effect

Front 20

Henderson-Hasselbalch equation describes

Back 20

the proportion of the drug that is charged a certain pH

Front 21

Because many drugs are charged, pH can have a

Back 21

major influence on where, along the intestinal tract, a drug is absorbed

Front 22

Where should weak acids be best absorbed?

Back 22

Stomach because more uncharged drug within the low pH environment

Front 23

a Weak Acid can be accumulated or concentrated where?

Back 23

in a basic compartment

Front 24

a Weak Base can be accumulated or concentrated where?

Back 24

in an acidic compartment

Front 25

Factors controlling absorption

Back 25

pKa of a drug, solubility in aqueous solution, dissolution rate if a solid, Surface area, circulation at site of absorption

Front 26

Volume of Distribution

Back 26

hypothetical volume of plasma a drug would distribute into if it were only distributed in plasma; this volume is different for each drug

Front 27

Volume of Dist. Equation

Back 27

Vd = bioavailable dose/ Conc. of drug in plasma

Front 28

Volume of Dist. Usages (3)

Back 28

1) tells about the behavior of a drug; very high Vd tells drug is accumulated in non-plasma compartments; low Vd implies within plasma (binded to proteins). 2) tells how big a volume is need in order to reach Tx conc. 3) used for other PK parameters, i.e. clearance

Front 29

Why can weak bases have a larger Vd in Ruminants?

Back 29

b/c weak bases accumulate in acidic compartments, and the Rumen is a large acidic compartment

Front 30

How are drugs eliminated

Back 30

either by direct excretion of by conversion to metabolites which are then excreted

Front 31

If a drug follows first order kinetics, then

Back 31

the metabolizing NZM for that drug is not saturated, thus rate of elimination is directly proportional to the drug conc.

Front 32

First order kinetics equation

Back 32

lnCt = -Ket + lnC0

Front 33

Relationship between rate of elimination and the time required to metabolized 50% of the drug (half life)

Back 33

0.693/Ke = t 1/2

Front 34

Clearance (CL)

Back 34

ability of the body to eliminate a drug by all routes; Metabolism and excretion

Front 35

CL formula

Back 35

CL = 0.693/t 1/2 x Vd units in ml/min Kg

Front 36

Effects of altering Ka, Ke, and dosage on concentration in plasma

Front 37

Bioavailability

Back 37

Amount of drug that enters circulation after first pass effect (fraction or %)

Front 38

Drug distribution will frequently be separated into

Back 38

phases

Front 39

A drug will equilibrate with ____ tissues rapidly, then ___ redistributes into less perfused tissues. This is called __C__

Back 39

A) Rapidly, B) Slowly, C) 2 compartment PK model

Front 40

If interval of administration is equal to half-life, then

Back 40

it will take about 4 doses to get to plateau concentration

Front 41

Repeated admin of a drug via any route other than continuous infusion, will cause concentration of drug to do what?

Back 41

to rise to a peak level, then fall to trough level

Front 42

The average of peak and trough concentrations is called

Back 42

plateau concentration

Front 43

Generally a drug is given at an interval

Back 43

that is less than or equal to 1/2 time for elimination

Front 44

0 order kinetics

Back 44

same AMOUNT (not %) of drug will be eliminated at each time interval rather than same fraction. i.e. alcohol- NZMS (systems) of inactivation become saturated