Pharma - Berto - L3 part 1

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Questions and Answers

Which factor has the greatest influence on the intensity of a drug's effect?

Genetic factors of the individual

Concentration at the receptor site (correct)

Frequency of drug administration

Drug receptor status

What typically occurs as a result of tolerance to a drug?

Enhanced efficacy with each subsequent dose

Consistent drug response regardless of administration frequency

Diminished response to the same concentration over time (correct)

Increased receptor density at the cell surface

Which of the following best describes the adaptation mechanisms associated with tolerance?

Temporary increase in drug receptors

Regulation of receptor number or functionality (correct)

Unchanged receptor status despite drug exposure

Permanent loss of receptor function

Which of these factors would NOT influence an individual's response to a drug?

Population density (B) Signup and view all the answers

What is the role of receptor turnover in pharmacology?

It contributes to processes like tolerance and hypersensitivity. (C) Signup and view all the answers

What is a likely result of increased drug administration frequency?

Lower drug efficacy over time (B) Signup and view all the answers

How can drug interactions occur according to pharmacological principles?

In both pharmacodynamics and pharmacokinetics (C) Signup and view all the answers

Which statement about receptor density is accurate?

Receptor density can vary and influence drug effects. (D) Signup and view all the answers

What happens to receptor functionality during the tolerance phenomenon?

It can be modified in both quality and quantity (A) Signup and view all the answers

What occurs when receptors are internalized but retain their phosphorylation level?

They are rapidly re-expressed on the membrane. (C) Signup and view all the answers

How is slow upregulation characterized in the context of receptor activity?

It results from changes in mRNA transcription. (B) Signup and view all the answers

In the context of pharmacological tolerance, which of the following statements is accurate?

Physical dependency can arise from chronic drug use. (B) Signup and view all the answers

What phenomenon occurs when there is chronic stimulation of receptors with antagonists?

Hypersensitivity due to receptor denervation. (B) Signup and view all the answers

What role does ubiquitylation play in receptor downregulation?

Signals for lysosomal degradation of receptors. (A) Signup and view all the answers

What is the significance of glutamate ionotropic receptors in the context of synaptic plasticity?

They enhance synaptic strength through increased receptor numbers. (C) Signup and view all the answers

What is a major characteristic of tolerance in relation to medication effects?

It modifies the efficacy of a therapy. (C) Signup and view all the answers

Which phenomenon results from overactivation of one receptor that causes desensitization of other receptors sharing the same pathway?

Crossdesensitization (D) Signup and view all the answers

How does desensitization specifically affect metabotropic receptors compared to ion channels?

It involves more phosphorylation steps. (C) Signup and view all the answers

What occurs during the rapid downregulation phase of receptor modulation?

Receptors are removed from the membrane by endocytosis. (A) Signup and view all the answers

What happens to receptors in the case of an antagonist that induces hypersensitivity?

The receptors are upregulated and become more sensitive. (B) Signup and view all the answers

What distinguishes heterologous desensitization from homologous desensitization?

It reduces the capacity of different receptors sharing the same pathway. (D) Signup and view all the answers

In the context of receptor desensitization, what role do beta arrestins play?

They mediate the uncoupling of receptors from G proteins. (A) Signup and view all the answers

What is tachyphylaxis in relation to receptor tolerance?

It describes a rapid decrease in response to a drug. (A) Signup and view all the answers

What is a key aspect of the mechanism that leads to downregulation of receptors?

It requires persistent phosphorylation signals. (C) Signup and view all the answers

Study Notes

Receptor Regulation Systems

Drug efficacy varies among individuals due to multi-level regulation; concentration at receptor sites is crucial for determining drug effect.
Receptor density on cell surfaces influences drug response; turnover affects tolerance and hypersensitivity.
Regulatory factors for drug response include drug receptor status, genetic factors, drug interactions, and tolerance.

Tolerance

Tolerance is a reduced response to a drug after repeated administration, necessitating higher doses for the same effect.
Degree of tolerance is influenced by drug dose and frequency; lower frequency reduces the risk of developing tolerance.
Compensatory mechanisms modify receptor numbers or functionality, potentially leading to pathologies.
Key characteristics of tolerance:
- Develops slowly and is reversible.
- Alters efficacy of therapy and can cause rebound effects when medication is stopped.
Tachyphylaxis occurs when tolerance develops rapidly after acute dosing.

Receptor Expression Modulation

Agonists lead to desensitization (reduced activity) and subsequent downregulation (decreased receptor numbers).
Antagonists may lead to hypersensitivity and upregulation, though these are less common.

Desensitization

Involves a decrease in receptor signal transduction capability upon ligand binding.
Can be homologous (specific to one receptor) or heterologous (affecting multiple receptors sharing the same pathway).
Affects different receptors uniquely; channels may naturally exist in a desensitized state.
Acute activation can result in rapid desensitization, followed by periods of inactivity.

Downregulation

Refers to a decrease in receptor numbers on the cell membrane.
Characterized by rapid and delayed phases:
- Rapid downregulation involves receptor removal through clathrin-mediated endocytosis.
- Delayed downregulation leads to lysosomal degradation of receptors.
Phosphorylation processes influence receptor fate (recycling vs. degradation).

Upregulation

Occurs mainly when receptors are chronically inactive due to antagonists.
Can be rapid (e.g., muscular hypersensitivity after prolonged antagonist use) or slow (e.g., long-term potentiation with glutamate receptors).

Pharmacological Tolerance

Defined as the need for increased doses to maintain drug effect due to desensitization of receptors.
Can lead to physical dependency and addiction; reminiscent of phenomena like cross-tolerance, where tolerance to one drug affects responses to another.

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Description

This quiz explores receptor regulation systems essential in pharmacology and how they influence drug efficacy. It will also cover the factors affecting individual responses to drugs, providing insight into pharmacokinetics. Prepare to deepen your understanding of these crucial pharmacological principles.