lecture4&5

Question 1

what form of an acid can transverse the membrane

Answer 1

the protonated form

Question 2

what form of a base can transverse a membrane

Answer 2

the unprotonated form

Question 3

what does the Henderson Hasselbalch equation tell us about drugs

Answer 3

it will give us a clue as to how much is protonated and so how much of the acid can transverse the membrane

Question 4

where do weak acids get absorbed

Answer 4

more likely in the stomach

Question 5

where do weak bases get absorbed

Answer 5

more likely in the intestines

Question 6

what cardiac factors impact distribution

Answer 6

cardiac output, regional blood flow, capillary permeability, binding to plasma proteins.

Question 7

what are the four main factors of distribution

Answer 7

cardiovascular, tissue binding, drug molecule size, and lipid solubility.

Question 8

what is biotransformation

Answer 8

reaction or metabolism of drugs can be categorized as phase 1 or phase 2. these can convert a parent compound into an active or inactive metabolite.

Question 9

what is phase 1 biotransfromation

Answer 9

generates a more polar molecule by exposing a functional group on parent group readies for phase 2 FORMS METABOLITE ACTIVE OR NOT

Question 10

what is phase 2 biotransformation

Answer 10

reaction yield a more water soluble conjugated product to be excreted. CONJUGATED

Question 11

what kind of reactions happen in phase1

Answer 11

oxidation reductive and hydrolytic

Question 12

what kind of reactions happen in phase2

Answer 12

glucuronidation, sulfation, acetylation, methylation,

Question 13

what is the first pass effect

Answer 13

that drugs absorbed by stomach or intestine will be carried by portal vein to the liver.

Question 14

what is the primary mechanism of drug elimination

Answer 14

renal excretion

Question 15

what processes effect renal excretion

Answer 15

GFR binding to plasma proteins, alklinization or acidification of urine

Question 16

what is another route for more lipophilic drugs to be excreted

Answer 16

fecal excretion

Question 17

what are the key parameters that impact drug dosage in patients

Answer 17

volume of distribution and clearance

Question 18

what is volume of distribution

Answer 18

the measure of the space in the body available to contain the drug. This is a theoretical number

Question 19

what is clearance

Answer 19

measure of the ability of the body to eliminate a drug

Question 20

what is volume of distribution as a formula

Answer 20

V=amount of drug in body/concentration of drug in blood or plasma. A high volume suggest the drug is moving but a low volume suggests little movement.

Question 21

what is the formula for clearance

Answer 21

CL=rate of elimination/concentration

Question 22

what is zero order elimination

Answer 22

this is when the elimination process is at capacity or saturated, so its independent of concentration. Linear on a normal scale nonlinear on a log scale

Question 23

what is first order elimination

Answer 23

non saturated process you will remove a fraction of the drug is removed every time period. Ie 50% every two hours non linear on a normal scale linear on a log scale

Question 24

what is flow dependent elimination

Answer 24

an organ has a high capacity but needs the right flow to get the drug there. Looks like first order kinetics

Question 25

what is capacity limited elimination

Answer 25

a point where the drug has saturated the elimination capacity of the system, but in dosage exceeds elimination this could lead to toxicity. Looks like zero order kinetics

Question 26

how does volume of distibution effect half life

Answer 26

the larger the volume of dist. The longer the half life

Question 27

how does clearance effect half life

Answer 27

the slower the clearance the longer the half life of the drug.

Question 28

what is the acuumulation factor

Answer 28

AF=1/fraction lost in one dosing interval. Only works if dosing is less than four half lives.

Question 29

what is the bioavailability

Answer 29

the amount of drug that reaches the systemic circulation. IV will be 100%

Question 30

what is the extraction ratio formula

Answer 30

ER= clearance of liver/hepatic blood flow or Q. the close to 1 the more its extracted and less is available.

Question 31

what is the bioavailability formula

Answer 31

F=extent of absorption of the gut or f, x [1-ER]

Question 32

what is steady state concentration Css

Answer 32

the point where what is reaching the blood is what is leaving the blood

Question 33

what is the formula for steady state

Answer 33

Css=dosing rate/Clearance or CL ti will take 4-5 half lives to reach the Css and is independent of the dose and dosing rate and only dependent of the half life of the drug.

Question 34

what is the maintenance dose

Answer 34

dose needed to maintain a steady state concentration in order to determine a maintenance dose the dosing rate must first be determined.

Question 35

what is the formula for dosing rate

Answer 35

ClxTC or target concentration this is for an IV dose, for oral does it would be Dosing rate/ F oral or bioavalibility

Question 36

what is the formula for maintenance dose

Answer 36

dosing rate x Dosing interval

Question 37

what happens to concentrations as the dosing interval increases

Answer 37

it will increase the peak and decease the trough concentrations which might or might not effect the patient.

Question 38

what is the loading dose

Answer 38

an initial dose that can be given in order to achieve the target concentration rapidly.

Question 39

what is the formula for loading dose

Answer 39

LD=V x TC / F

Question 40

how many half lives does it take for a drug concentration to be considered negligable?

Answer 40

4-5 half lives.