Lecture 2

Question 1

How do drugs act

Answer 1

receptors are molcular targets for most the drugs
drugs needs to find the right receptor

drug + receptors (recognition site)  

drug receptors complex

physiological response 
--> contraction relaxation response

Question 2

What are drug actions

Answer 2

they are specific or non specific

Question 3

Whats the access of receptors

Answer 3

receptors is access able when she Site binds to form a Complex which form the effects -

this is when the drugis dissolved in Certain Solvents Called vehical → this is to deliver to a certain site - the right solvent X is important to choose the right receptor

Question 4

what are different types of Target drugs

Answer 4

enzymes
DNA
Carrier portions
wh channeles
receptors

Question 5

What are targets of drug action

Answer 5

these targets are protien macromolecules except DNA
Cancer therapeutic drugs can be used when binding with the drug

Question 6

What are receptors

Answer 6

receptors are Transducers Capable of converting the energy of the environmental Stimulus into nerve Impulses

Question 7

discuss and give an example of scientific Action of drugs on receptor

Answer 7

= most common site for the action of drugs
= located on the cell membrane; receptors for steroids (lipophilic molecules) are located inside the cell
= knowing how long medication is effective
= cell membranes receptors are much easier to get too
= penerate the cell membran takes much longer
= if the cell penerate bilayers - it is easier
example
example: brown inhalers is a steroids that will bind inside the cells - need to take these puffs every few hours as the receptors dont fight it and the seriods drugs keeps on working

Question 8

What are the Criteria of receptor Classification

Answer 8

1) selective agonist:
2) theres a unique rank order of agonist at the receptors being classified
3) there agonist with high selectivity for the receptors compared wit thier potancy at other receptors

Question 9

What are selective antagonist

Answer 9

there should be a drug to block the receptors
are potent selective antagonists available which help characterising them
ligands binding studies - dissociation constant should correlate with data from functional studies
ligands +chemical helps marking them -> see where the drug is going

Question 10

What are Transduction Pathways

Answer 10

provides further definition for receptors under investigation

Question 11

What are molecular structures

Answer 11

receptors Structure and aasequence
provide definitive evidence Of receptor identity

Question 12

example of drugs acting on receptors - related to histomines

Answer 12

histomine receptors:
is allergic to things which are pollen
when body is exposed to the allergens - the chemical is released called the histomine

Question 13

Whatare H1 raptors

Answer 13

blockage by antihistamines resulting in treating allergic and inflammatory responses

Question 14

What are H2 receptors

Answer 14

h2 receptors -blockade by antihistomines resulting in treating peptic ulcer - due to receptrs already blocked

Question 15

explainations of the receptors histamines

Answer 15

his - bistominestomine is released -> symtomes are fored showing that they are binding to the receptrs
-> induces different effects -I
-> medication given is antihistomine - symotoms disapperar
-> antagonist blocked H1

Question 16

What are Scientific drug action

Answer 16

they know where 70 go

Question 17

Whatare scientis tring action on ion channels

Answer 17

pore that is on the cell membrane
○ pores in the cell membranes which can open or close to allow or prevent the passage of ions down thier concentration (electrochemical) gradient
○ opening or closing of channels depends on the structure of the macromolecules protien forming the pore
○ drugs may bind to differet sites of this macromolecules which will affect the closing or opening of the channels
○ when channels open induces negative ions get in
○ less depolarisation anxiety - much more calmer
○ ions that hep in transport thes drugs bind to the sides
○ this is to see if it is open

Question 18

example of ion channels

Answer 18

benzodiazepines anti anziety hypnotic - increases Conductance of Chlorine rons by freecency of openning con

Question 19

Scientific action on Carrier protiens

Answer 19

-> transfer material
-> located in the cells membrane or intracellular organelles
-> transfer materials against thier concentration gradient
active transport process by using energy rom the cell

example of carrir protiens:
□ sodium pumps pumps sodium out and pottassium into cells
□ this i by using ATP
□ Na + /K+ ATPase, which slipts atp and relaease energy
□ action of pumps can be inhibited by cardiac glycosides
□ example digoxins in patients with heart failure
□ works of carrier protiens
examples of carrier protiens:
sodium chloride cotransporter in kidney can be inhibited by
thiazide duiretics eg chlorothiazide
both the above are used in patients with heart failure
works on the kidney enxymes more

Question 20

What are scientia action on enzymes

Answer 20

enzymes are macro molecular protiens that Catalyses or Speeds up the rate of Chemical reaction in organisms _ drugs can bind to the enzyme and inhibit and interfere With action

Question 21

What are the examples of drug action of enzyme

Answer 21

Aspoun inhibit Cyclooxygenase enzyme leading the withabiton of formation of local mediators.
→ they produce good and bad prostaglandin
o some are involved Inflamation

Question 22

what are the Scientific action of Drugs on DNA

Answer 22

Drugs may bind to DNA and modify in cell devision process - for example anticancer DRUG

Question 23

Non Scientific actions of a drug and thier class are?

Answer 23

exhibit poor structural relationships
required in nign conc CMM)
examples
general aneasthnic
dealwith Conscious

Question 24

\ what are non Specific action of drugs <

Answer 24

Laxative + diuretics
Bulking effects methylcellulose

Question 25

what are drugs effects

Answer 25

beneficial or therapeutic effect results from binding of a drug to sites with high affinity
- this drug shows high affinity for a specific site seen in most subjects
-> adverse effects results when drug bind to sites that re not desierd may be seen in some indivisuals
-> depending on the gentic factors variation in metabolism leadd to iosyncratic response
sufficent for eveeryone
hydrosyntronic - effects difficult yo predict

Question 26

what are drug effects of be neficial and adverse effect

Answer 26

\ 1. mediated by the same mechanism eg hypoglucaemia induced by insulin
2. anticuogulant induced bleeding
3. mediated by the same mecanism but in different tissues
4. example cancer drugs kill both cancer and healthy tissues
5. mediated by different mecanisms
6. eg. anti allergic actions but also has a anti musarrinic effects
anti allegic - histomines

Question 27

What is a Therapeutic index

Answer 27

the therapeutic indexis a camparnsionof the amountof therapeuticagent thatCause sthetherapeutic
effect to the amount that causes toxic effects

Question 28

Toxicity and therapeutic index

Answer 28

weather the drug has a narrow or Can be wide difference is huse
therapeutic ratio=TD50 / E D 50

Question 29

give5 facts for therapeutic index

Answer 29

• A high therapeutic index is preferable to the low one
• this corresponds to a stituation in which one would have to take a much higher amount of a drug to do harm than the amount taken to do good
• the narrower this margin the more likely it is that the drug willl produce unwanted effects
• generally a drug with narror therapeutic range
• little difference bwteeen toxic and therapeutic dose
• its dosage adjusted according to measurements of the actual blood levels
• achieved in the person taking it
• this may be achieved through therapeutic drug monitoring protocols
• examples of drugs with a narrow therapeutic range that may require drug monitoring
• both achieve therapeutic levels and minimize toxicity include
• digoxin, theophylline
• some antibiotics require monitoring primarilty to minimise adverse effects
drug selectivity rather than specifity
a single drug does not cause a single specific effect because no drug binds to a single site or activates a single mechanisms
so drugs actions are selective rather than specific
decides which is better

EXAMPLES OF ACTIONS OF DRUG ON ENZYMES:
○ aspirin inhitibts cyclo oxygenase enzyme leading to inhibitation of ormation of prostaglandins (local mediators)
○ they produce good and bad prostaglandins
○ someare involvd in inflanation
○ some duiretics inhibits carbonic anhydrase leading to an increase in urine output
○ some antibiotics interfere with the synthesis of DNA of bacteiaas
○ aspirins can cause stomuch bleed as causes good prostoglands so has to have an other medicatoon
○ nitrates used in patients with angina activate the guanylate cyclase enzyme in blood vessels
○ results in an increase in formaion of cyclic GMP leading to relaxation of the wall of bllood vessels
○ thus more blood can flow to supply heart muscles
○ acts on enzymes - for relatation of walld of the vessels
○ GCE blood increases flows heavier
specific actions of drugs:
on DNA:
DRUGS may bind to DNA and modifty thier replication in cell divison process
for example:
anti cancer drug, cis platins

non specific actions of the ddrugs:
drugs of this class:
• exhibit poor structural relationship
• required in high concentration (mM)
• examples
• general anaesththisc
• deals with conscieus
• move soluable
• work by deminishing the actiity of the excitable tissues by dissolving in membranes
• thier potency corralates as well with degree of lipohilicity
• brain areas assoociated with consciousness are very sensitive
non specific actions of the drug
some laxatice and duiretics:
bulking effects methylcelllulose bran mannitol