Types of Pharmacologically Active Agents by P notes

Question 1

e…. and e….. both act via receptors

Answer 1

endogenous and exogenous agents both act via receptors

Question 2

Endogenous Agents - Name some examples and state the origin of endogenous agents

Answer 2

Endogenous agents (internal origin)

Hormones

Neurotransmitters - Ach, NA

Growth factors

Vaso-active factors such as endothelin or nitric oxide

Question 3

Exogenous Agents - Name some examples and state the origin of endogenous agents

Answer 3

Exogenous agents (external origin)

‘Drugs’ that modify the effects of endogenous agents

Question 4

One line definition of drug

Answer 4

Drug - chemical compound that when applied to a biological system alters its function in a specific manner

Question 5

State targets for drugs

Answer 5

Drug target - any biological binding/recognition element (usually proteins) for drugs

Receptors

Ion channels

Carriers or transporters

Enzymes

Question 6

Agonists or antagonists acting at the receptor for the endogenous agent - elaborate on difference in a single sentence

Answer 6

Agonists are drugs that combine with receptors to produce a response
Antagonists are drugs that combine with receptors without producing a response (no efficacy)

Question 7

Type of antagonists elaborate

Answer 7

Antagonists are drugs that combine with receptors without producing a response (no efficacy)

Competitive - bind to the same site as the endogenous agent, reversible and overcome by a higher concentration of agonist

Can have irreversible competitive agonists which bind to the binding site permanently, reducing the maximum response that can be achieved by the agonist. The antagonistic action will also increase with exposure time as more of the binding sites become irreversibly bound to antagonists.

Non-competitive - bind to an allosteric site, changing the tertiary structure of the receptor, reducing its affinity for the agonist. Effects cannot be reversed by increasing the agonist concentration

Occupation of receptor determined by affinity, activation of receptor determined by efficacy

Higher affinity = lower concentration of drug required

Question 8

Occupation of receptor determined by ….., activation of receptor determined by …..

Higher affinity = …. concentration of drug required

Answer 8

affinity, efficacy
lower

Question 9

Exogenous agents have an ….. origin

They can be drugs that modify the effect of endogenous agents

Agonists bind to a receptor and cause a ….. change, leading to a cellular response, so have ……

…. Prevent agonist mediated responses by preventing a drug or endogenous agent from binding in a listing response so have no …. but have ….. and can be ….. and …..

Answer 9

external
conformational
affinity and efficacy
antagonist
efficacy, affinity
competitive and non-competitive

Question 10

Some drugs can act indirectly
- Physical antagonism - elaborate
- Drugs which affect the release of a substance - elaborate
- think of 2 other mechanism - elaborate

Answer 10

Physiological antagonism is the of a substance that produces affects counteracting, those of another substance, using a mechanism that does not involve binding to the same receptor
. Some drugs can affect the release of a substance for example, botulinum toxin prevents the release of neurotransmitters in a presynaptic neuron
Making affect the metabolism of a drug, where the breakdown of a drug may lead to further effects
They can affect the reuptake of an endogenous agent, for example, a reuptake inhibitor inhibits plasmalemma transporting mediated reuptake of neurotransmitter from the synapse

Question 11

Drugs that act indirectly

Affect release of endogenous agent -

Affect metabolism of endogenous agent

Affect reuptake of endogenous agent -

Answer 11

botulinum toxin (SNARE)
neostigmine (anti-AchE)
hemicholinium (choline transporter)

Question 12

Drugs acting on membrane transporters or ion channels
Name
1 drug for Ca2+ channel blocker
1 for K+ channel blocker
2 for Na+ channel blocker

Answer 12

amlodipine
TEA
TTX, lidocaine

Question 13

Drugs can act on membrane, transporters or ion channels

You can have blockers for the aqueous pores in membranes and specific ion channel blockers, like potassium, channel blockers

Latest updating modifiers can increase or decrease the opening probability of gated channels

Proteins require a confirmational change for transfer of the bound solute across the membrane and inhibitors prevent the transport of solute in the transporter

Cocaine is a competitive inhibitor of monoamine transporters

Omeprazole is an inhibitor of the proton pump

Answer 13

pharmacology facts

Question 14

Enzymes and enzyme inhibitors
- recall & elaborate

Answer 14

Enzyme inhibitors prevent the normal reaction from taking place

Competitive

Similar conformation to substrate

Bind reversibly to the active site

Enzyme has the same Vmaxas inhibition is overcome by increasing [substrate]

Non-competitive

Binds to an allosteric site permanently

Decreases the Vmaxas inhibition is not overcome by increasing [substrate]

False substrate

Acted upon by enzyme to produce an abnormal product that interferes with cellular processes

Conversion of a drug to its active form

Question 15

Enzymes and enzyme inhibitors

Competitive inhibitors bind to the active site in place of the substrate, for example, captopril binds to the angiotensin converting enzyme

Non-competitive inhibitor is bind to a separates binding site on the enzyme which changes the shape of the tertiary structure of the enzyme for example, aspirin causes irreversible inactivation of cyclo-oxygenase enzyme

False substrate is where a drug undergoes enzymatic processing to form an abnormal product that interferes with cellular processes

Fluorouracil inhibits DNA synthesis by replacing uracil in purine biosynthesis, and is used as an anti-cancer drug

This can also be a cause of toxicity by leading to the formation of a reactive metabolites, for example, the effects of paracetamol on liver damage (can cause it with excessive use)