Dose, Potency and Efficacy

Question 1

what is potency

Answer 1

concentration or dose of a drugs maximal effect

EC50 or ED50

nearest to 0 in x-axis

Question 2

what is efficacy

Answer 2

maximum response or effect

checked before potency

farthest from 0 in y-axis

Question 3

discuss the dose-response curve

Answer 3

x: dose of drug; 0-30 mg basta highest dose

y: different effects of drug

Question 4

discuss subtherapeutic dose

Answer 4

low doses that will not provide the drug effect

below min effective dose

Question 5

discuss therapeutic dose

Answer 5

there is clinically significant effect

has plateau - peak effect/efficacy

once drug plateaus inc dose will not inc relief only side effects

Question 6

discuss median effective dose

Answer 6

ED50: dose that produces therapeutic effect in 50% of popu

seen in quantal dose curve
- x: concentration of drug in plasma
- y: percent of indiv responding

Question 7

discuss median toxic dose

Answer 7

TD50: dose that produce toxic effect on 50% of popu

Question 8

discuss therapeutic index

Answer 8

ratio of TD50/ED50

OTC: wide therapeutic index = safe

chemo and antiarrhytmic: narrow = side effects

Question 9

discuss therapeutic window

Answer 9

dose where you get good effect

varies from pt to pt and drug - pedia vs adult doses

index is wider than window

Question 10

discuss median lethal dose

Answer 10

dose that kills far from TD and ED

Question 11

what are the 2 primary routes of administration

Answer 11

alimentary - passes GI tract

non-alimentary - outside GI tract

Question 12

discuss oral route

Answer 12

convenient, cheap and self-administered

limited - not all can be tablet, capsule or syrup

has first pass effect = less bioavailability

can cause gastric irritation

may or may not be take c meals

cannot give to unconscious pt

Question 13

discuss sublingual

Answer 13

under tongue - venous plexuses straight to systemic

fairly rapid for emergency - 10 to 15 mins

avoids first pass but limited

ask pt to not swallow saliva until dissolved

Question 14

examples of sublingual drugs

Answer 14

anti-HTN

analgesics

nitroglycerine - MCI

Question 15

discuss rectal route

Answer 15

non-cooperative pt - geria, pedia, unconscious

limited and unpredictable - since has feces and causes irritation

direct to venous plexuses in rectum

suppositories

Question 16

discuss inhalational route

Answer 16

rapid onset - goes direct to lungs

bronchodilators or GA

direct but limited

need tot each pt how to use inhalers

Question 17

discuss topical route

Answer 17

local effect on outer skin - lesions, infection, eczema, insect bites

eye drops, ear drops

Question 18

discuss transdermal

Answer 18

on skin but to systemic

nicotine patches or nitroglycerine buccal mucosa spray

Question 19

discuss injection

Answer 19

quickest onset but hard to self-administer

needs aqueous solution

Question 20

discuss IV injection

Answer 20

most direct - vein

bypasses first pass

needs catheter

most hazardous since cannot be removed

Question 21

discuss IA injection

Answer 21

high local concentration to tissue - direct to organ

chemo on kidneys

Question 22

discuss SQ injections

Answer 22

fat is poorly vascularized = slow absorption

can be depository - releases p 24 hrs

large volumes not feasible

insulin

Question 23

discuss IM injections

Answer 23

effect in 15 mins - vaccines

if drug is diff via IV

painful since longer needle and can cause tissue damage

Question 24

discuss subarachnoid injections

Answer 24

on arachnoid matter - drugs mixed in CSF

spinal anesthesia and chemo drugs for pedia

Question 25

discuss epidural injections

Answer 25

above epidural space - via epidural catheter used in labor or big surgeries - local anesthesia

Question 26

discuss tendon sheath or bursa injections

Answer 26

for ligaments tears, muscle tears and OA PRP steroids local anesthetics dry needling hydrodissection

Question 27

what is bioavailability

Answer 27

amount of unchanged drug reaching systemic circulation

Question 28

what affects bioavailability

Answer 28

GI absorption - first pass plasma protein binding - albumin, globulin adipose tissue storage biotransformation - inc or dec elimination

Question 29

discuss fluid mosaic model

Answer 29

cell membrane has bi-lipid later c proteins drugs need to be lipophilic to pass

Question 30

discuss selective barrier

Answer 30

BBB limits amount of drugs that can pass since any drug can cause neuro effects

Question 31

discuss passive diffusion

Answer 31

from high to low concentration permeability coefficient - substance needs to be permeable

Question 32

rate of diffusion depends on

Answer 32

permeability coefficient concentration gradient area - inc area = inc diffusion thicker = less diffusion

Question 33

discuss active transport

Answer 33

uses ATP to pass from low to high

Question 34

discuss facilitated diffusion

Answer 34

uses carrier protein to faci or speed up diffusion

Question 35

discuss endocytosis and exocytosis

Answer 35

cell membrane can engulf drugs endo - embrace drug then breaks of membrane and brings insed cell exo - drug inside cell the engulf it will break membrane then release out