• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

Card Range To Study

through

image

Play button

image

Play button

image

Progress

1/27

Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

27 Cards in this Set

  • Front
  • Back

What is Pharmacokinetics?

What the body does to the drug,




Think ADME:


Adsorption


Distribution


Metabolism


Excretion



What is pK?

The pH at which half of the molecules are ionised.

The four main types of proteins drugs act on...

Enzymes


Receptors


Transporters


Ion channels

What is Pharmacodynamics?

The effect of Drug on Body.




allows us to compare effectiveness of drugs.


determine appropriate dose for patient.

What does an Antagonist do?

Activates receptor

What does an Antagonist do?

Inhibits receptor

Describe allosteric action of a drug on an ion channel...




eg. Benzodiazipines on a GABA(A) receptor.

Benzodiazipan will enhance the binding of GABA by changing shape of binding site and therefore affinity.

What are the four main types of Receptors?

Ligand Gated Ion channels


G Protein coupled receptor


Tyrosine Kinase link receptor


Intracellular receptor

Two types of Ion channels?

Ligand gated (think ACh)


Voltaged Gated (think Ca2+ ion channels at terminal ends)

Describe the functions of these three types of G protein receptors, Gs, Gi, Gq

Gs- Stimulates Adenyl cyclase


Gi - Inhibits Adenyl cyclase


Gq - Activates Phospholipase C

Which of the follow is an example of a Gs receptor?




Alpha 1, Alpha 2, Beta1/2

Beta 1/2 are both examples of Gs receptors as they stimulate adenyl cyclase, activating Ca2+ channels, flooding the cell with calcium ions

What kind of G protein receptor is Alpha 1?

Alpha 1 is a Gq receptor as it actives the enzyme Phospholipase C.

What kind of G protein receptor is Alpha 2?



Alpha 2 is a Gi receptor as it inhibits the active of Adenyl cyclase. It is a type of autoreceptor.




eg. post-ganglion, sympathetic neurones, where its activation will inhibit the release of neurotransmitters (Ca2+ cannot enter cell and allow fusing of vesicles into synaptic cleft)

There Two major classes of intracellular receptors, Class I and Class II.




Where is Class I located?

The Cyotplasm. These receptors form Heterodimers, and their ligands are endocrines(eg steroids and lipophilic hormones which can cross the celle membrane easily)

Where are Class II intracellular receptors located?

The Nucleus. Also form Heterodimers, Ligands tend to be Lipids.

List the following Drug targets in order of their speed in eliciting a response, from fastest to slowest:




Nuclear receptor


Ligand-gated ion Channels


Tyrosine Kinase-linked receptor


G-protein coupled receptors

Ligand-gated Ion channels (milliseconds)


G-protein coupled receptors (seconds)


Tyrosine kinase-link receptor (minutes)


Nuclear receptors (Hours)

What are the axis of a Dose response Curve?

X-axis: Agonist concentration


Y-axis: % response

What are the two types of Dose response Curves?

Graded, and Quantal


- Allow Potency and Efficacy to be determined

Describe Graded Dose-response curves...

-The response of a particular system eg isolated piece of smooth muscle


-Produced by plotting Pharmacological response against Log dose


-Graded response eg half of all receptors are inhibited

What Parameter can be determined from a Graded dose response curve?

The maximal response

Describe Quantal dose-response curves...

- Gives a specificed response in a certain Population


-All-or-Nothing response, either an animal/individual in a population will response or they will not.


- Produced by plotting % Responding against log dose

What is the difference between Potency and Efficacy?

Potency: How well a drug can BIND to a receptor (in order to elicit a response)


Efficacy: Describes the ability of an agonist to ACTIVATE a receptor.




ie. efficacy is the maximal effect a drug can produce, an agonist with a high efficacy will be a Full Agonist, while a drug with a lower efficacy will be a Partial Agonist.

What does Kd represent?

Kd = the dissociation constant of a particular drug. (think of it as how likely a ligand will dissociate from receptor)


-can be used to identify an unknown receptor


-can be used to quatitively compare the affinity of different drugs on the same receptor.


-There is an inverse relationship between Kd and affinity




i.e a lower Kd indicates a tighter ligand-receptor interaction and therefore a higher affinity.

How is Kd found?

Kd is the value at which 50% of drug is bound to the receptor, therefore when 50% are bound at a lower concentration there will be a higher affinity, as Less drug is needed to bind 50% of receptors.

Why does Higher affinity not always mean a high Efficacy?






*remember efficacy is the ability of a drug to activate a receptor ie full agonists have high affinity, partial have low affinity*

A drug may have a high affinity for a receptor but it could infact be an antagonist for example which would inhibit the receptor instead.




similarly perhaps the drug has a high affinity but it binds else where on the receptor and not the area which would activate it.

Summary of Efficacy, affinity and response curves.

- % Binding against log agonist response curve can be used to calculate Kd (the conc at which 50% of receptors are bound). This will tell us about the affinity of the drug but not necessarily the efficacy.


- To see efficacy we need a graded dose response curve with % response of tissue against log concentration of drug/dose. we can see maximum response here and at what concentration, determine if full/partial agonist or possibly antagonist.



What exactly is Potency and how can we calculate it?

*potency is how well a drug can bind to a receptor in order to elicit a response. it depends on affinity, efficacy, receptor density, and efficiency of the intrinsic stimulus response mechanism*


- It is the amount of drug needed to produce a given effect


-calculated as 50% of tMax


i.e the lower the EC50 (50% tMax) the higher the potency as a lower concentration is required to cause a response.




must be determined from graded-dose response curves.