Pharmacodynamic

Question 1

What are Agonists?

Answer 1

Agonists are drugs that bind to receptors and activate them, producing a full response

Question 2

What are Antagonists?

Answer 2

Antagonists are drugs that bind to receptors but do not activate them. They block receptor activation by agonists.

Question 3

What is the difference between Agonists and Antagonists?

Answer 3

Agonists: Activate receptors to produce a full response.
Antagonists: Bind to receptors without activating them, blocking agonists.

Question 4

What is a Partial Agonist?

Answer 4

A partial agonist binds to receptors and produces a suboptimal response, less than a full agonist but more than an antagonist.

Question 4

Visual Summary of agonist, antagonist and partial agonist

Answer 4

Agonist: Full activation
Partial Agonist: Less activation
Antagonist: No activation

Question 5

What is Tolerance?

Answer 5

Tolerance is a decreased response to the same dose of a drug with repeated (constant) exposure. For example, with morphine, the body gradually loses its response over days or weeks.

Question 6

What is Tachyphylaxis?

Answer 6

Tachyphylaxis is a rapid reduction in the response from a receptor with repeated administration of a drug. For example, with labetalol, the response can diminish very quickly, sometimes after the first dose.

Question 7

What is Sensitization?

Answer 7

Sensitization is an increased response to the same dose of a drug with repeated (binge-like) exposure. For example, with amphetamines, the body’s response can become stronger with repeated use.

Question 8

What is pharmacokinetics?

Answer 8

Pharmacokinetics is the study of the effect of living systems or the body on drugs.

Question 9

what are the two main types of drug actions?

Answer 9

1. Non-specific (e.g., antacids decreasing acidity in the treatment of gastroesophageal reflux disease).
2. Receptor-mediated actions

Question 9

what are the target proteins that drugs act on?

Answer 9

Drugs act on receptors, enzymes, carriers/transporters, and ion channels.

Question 10

what are receptors?

Answer 10

Receptors are membrane-bound macro-molecular structures to which drugs or endogenous substances bind to produce an effect, initiating a chain of events leading to the drug’s observed effects.

Question 11

what is the simplified process of receptor-mediated action?

Answer 11

1. drug + receptor
2. effect
3. drug-receptor complex [DR]

Question 11

What are the characteristics of receptor-mediated action?

Answer 11

Minute quantities of drugs are required to produce drug action.
Most drugs are specific in their action, producing a specific action on specific target tissue.
Specificity: “lock and key” – some drugs may only activate one receptor type, others several.
Drugs with similar actions are structurally related to one another.
Receptors mediate the actions of both pharmacologic agonists and antagonists.

Question 11

what is the lock and key theory of drug action?

Answer 11

Every ‘lock’ (receptor) has its own ‘key’ (drug).
The ‘lock’ is precise in nature and would only open with a precise key.
The ‘key’ fits the target ‘lock’ specifically to produce an effect.

Question 12

what is drug specificity?

Answer 12

“Lock and key” – some drugs
may only activate one receptor type,
others several
Many individual drug classes only bind to specific targets (specific receptors).
Individual targets (receptors) only recognize specific classes of drugs.

Question 12

what is affinity in drug-receptor interactions?

Answer 12

affinity is the tendency of a drug to bind to a particular receptor.

Question 12

what is efficacy in drug-receptor interactions?

Answer 12

efficacy is the ability of a drug to generate a response when bound to a particular receptor

Question 13

what is potency in drug-receptor interactions?

Answer 13

potency is a measure of drug activity expressed in terms of the amount required to produce an effect of given intensity. (measures how much of the drug is needed to produce a certain effect. the less drug given the more potent it is)

Question 14

what is the maximum effect in drug-receptor interaction?

Answer 14

The maximum effect is the maximum possible effect produced after a drug is administered.

Question 15

what is the implication of drug-receptor interaction?

Answer 15

1. drugs can possibly alter the rate of any bodily function.
2. drugs cannot impart entirely new functions to cells.
3. drugs do not create effects, only modify ongoing ones.
4. drugs can allow for effects outside of the normal physiological range.

Question 16

what is synergism in drug-receptor interactions?

Answer 16

synergism is when the result effect is greater than the sum of their individual effect.

Question 16

what is potentiation in drug-receptor interactions?

Answer 16

potentiation is when the resultant effect is greater than the effect of any one of the agonists alone.

Question 16

what is antagonism in drug-receptor interaction?

Answer 16

antagonism is when the effect of the agonist is reduced by the presence of an antagonist

Question 16

what is competitive antagonism?

Answer 16

competitive antagonism is when the agonist and antagonist compete for the same receptor based on their concentration at the receptor site and their affinity for the receptor.

Question 17

what are the types of competitive antagonism?

Answer 17

1. reversible antagonism-the antagonist has a similar affinity for the same receptors as the agonist, and the antagonism can be reversed by increasing the quantity of the agonist. The antagonist can be displaced if a sufficient amount of agonist is administered.
2. irreversible antagonism- the antagonist binds irreversibly to the receptor, forming a covalent bond. This reduces the number of receptors available for the agonist and cannot be displaced even if more agonist is administered.

Question 17

what is non-competitive antagonism?

Answer 17

non-competitive antagonism occurs when the antagonist binds to a different allosteric site on the receptor to prevent receptor activation. also known as allosteric antagonism

Question 18

what is physiological antagonism?

Answer 18

physiological antagonism is when an antagonist (or agonist) binds to a particular receptor where it produces a response that opposes the effect of the primary agonist

Question 19

what is chemical antagonism (chelating agent= Metal toxin binds with drug & is excreted in the
urine)

Answer 19

chemical antagonism occurs when the antagonist binds chemically to the agonist to form a biologically inactive complex, preventing the agonist from binding to the receptor or target.

Question 20

what is pharmacokinetic antagonism?

Answer 20

pharmacokinetic antagonism occurs when the antagonist enhances the metabolism or excretion of the agonist, dealing with drug interactions.

Question 21

What are the different types of antagonism?

Answer 21

1. competitive-Agonist and antagonist compete for the same site on the same receptor (reversible or irreversible).
2. non-competitive-Antagonist blocks the effect of the agonist by binding to a different site on the same receptor.
3. chemical-Antagonist binds directly with the agonist to form an inactive complex.
4. pharmacokinetic- Antagonist affects the absorption, distribution, metabolism, or excretion of the agonist.
5. physiological-Antagonist produces an opposing physiological effect to the agonist.