bases of pharm

Question 1

define affinity

Answer 1

effectivness of binding

Question 2

define intrinsic efficacy

Answer 2

response to ligand binding

Question 3

what is potency

Answer 3

affinity+intrinsic efficacy

Question 4

what is Bmax

Answer 4

maximum bining capacity => limited by receptor number

Question 5

What is Kd

Answer 5

concentration of ligand required to occupy 50% of receptors, higher the value the less effective is the drug

Question 6

define EC50

Answer 6

50% of maximum response potency affected by receptor number, potency and ability to mediate a response

Question 7

define E max

Answer 7

maximum response

Question 8

define IC 50

Answer 8

concentration that inhibits 5 0% of response

Question 9

define oral bivelence

Answer 9

Proportion of drug given orally /or any other rout (not IV) that reaches circulation unchanged

Question 10

What’s LD/TD 50 and ED 50

Answer 10

LD50 => maximum total dose (lethal)

ED50 => maximum effective dose (effective)

Question 11

define volume of distribution

Answer 11

Theoretical volume into which drug is distributed if this occurred instantaneously’

Question 12

why bis pH of urin important in drug elimination

Answer 12

weak acids eliminated better with alkaline urine and opposit true, nit reabsorbed

Question 13

define pharmacokinetics

Answer 13

what body does to the drug

Question 14

define pharmacodynamics

Answer 14

what drug does to thebody

Question 15

what is the difference between eneteral and paraenteral drug delivery

Answer 15

enteral =through GI (oral, sublingunal, rectal)

paraenteral=not through GI (IV, IM, transdermarl, subcutenous intrathecal)

Question 16

what factors affect drug absorption

Answer 16

pasive: lipid solubility, pH, size
active: active transport system, splanchnic blood flow, drug distruction

Question 17

what factors affcte biopvelence

Answer 17

age, food (less important with hydrophylic), vomiting, malabsorption, first pass metabolism

Question 18

first pass metabolism give examples

Answer 18

any metabolism that occurs before drug enters the circulation
GI => acid, proteolytic enzymes, eflux pump
Liver

Question 19

define distribution + examples

Answer 19

spread of drug around the body depdnednt on
water/fat solubility
protein binding tissue and blood
density of binding sites and mass of tissue

Question 20

what are the different protein types that bind drugs and what kinds of drugs do they bind

Answer 20

1. Albumin =>Acidic drugs
2. Globulins =>Hormones
3. Lipoproteins and Acid Glycoproteins =>Basic drugs

Question 21

When is protein binding of high significance

Answer 21

narrow theraputic window, high protein binding, low volume of distribution

Question 22

what can affcet drug protein binding

Answer 22

hypoalbuminuria, pregnancy, renal failure, other drugs

Question 23

how is volume of distribution (Vd) calculated

Answer 23

total amount of drug in the body/plasma drug concentration at time 0

Question 24

where dose drug distribiut to and what deteremins that distribution

Answer 24

intracellular anmd extracellular compartments (apparent volume) and plasma => dependent on lipid solubility and transporters

Question 25

What does Vd indicate

Answer 25

Vd =5l => drug in blood Vd = 15 => drug in extracellular fluid and plasma Vd > 15l => drug in intracellular May also have higher Vd if tissue bound i.e. anaesthetics and adipsoe tissue

Question 26

What processes are active in phase 1 metabolism and what is the enzyme involved

Answer 26

Cytochrom P450 => hydroxylarion, reduction, oxydation

Question 27

name some incuces of Cytochrom P450 | B.S CRAPS

Answer 27

``` Phenytoin Carbamazepine Barbituates Rifampicin Alcohol (Chronic) Sulphonylureas & St. John’s Wort ```

Question 28

name some inhibitors of Cytochrom P450 | I AM SECS GOD

Answer 28

``` Grapefruit Juice Omeprazole Disulfiram Erythromycin Valporate Isoniazid Cimetidine & Ciprofloxacin Ethanol (Acutely) Sulphonamides Metronidazol ```

Question 29

what is the purpose of phase 1 and 2 of metabolism

Answer 29

1 increase recativity | 2 conjugation to water solluble compound

Question 30

What are the 3 molecules used in phase 2 conjugation, what are the cofactors

Answer 30

Glucoronic acid, sulphayte ions, glutathion cofactor, uridine diphosphate glucuronic acid (UDPGA).

Question 31

What factors affect elimination

Answer 31

renal blood flow, filtrate pH, plasma protein binding, lipid solubility, organic cations/anions,

Question 32

define clearance

Answer 32

The volume of plasma that is completed cleared of drug per unit time (sum of hepatic and renal)

Question 33

what is teh equation for clearnce

Answer 33

Clearance=(Amount in urine × Urine flow rate)/(Arterial Plasma Concentration)

Question 34

what factors affct clearnce

Answer 34

heart => output renal=> renal elimination hepatic=> hepatic elimination

Question 35

what is the equation for half life

Answer 35

Half Life= (0.693 × Volume of Distribution)/Clearance

Question 36

what is the link between Kd and kinetics

Answer 36

1st order => drug concentration close to Kd | 0=> drug concentration much higher than Kd

Question 37

how is loading dose calculated

Answer 37

Loading Dose (Dose L)= Vd ×Steady State Concentration in Plasma (CpSS)

Question 38

what drug enhances actions of penicillin by reducting tubular excretion gibve another genearl example

Answer 38

probenecid NSAIDs