Pharmacology Chapter: Sympathomimetics & Catecholamines

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Questions and Answers

Which of the following is a sympathomimetic drug that increases the 'fight or flight' response?

Insulin

Epinephrine (correct)

Glucose

Acetylcholine

Catecholamines, like epinephrine, are rapidly broken down by which enzyme?

Amylase

Lactase

Lipase

Monoamine oxidase (MAO) (correct)

Which of the following is a noncatecholamine drug that has a longer duration of action?

Isoproterenol

Ephedrine (correct)

Dopamine

Norepinephrine

What is the primary effect of antiadrenergic drugs?

Decrease 'fight or flight' responses Signup and view all the answers

Which of the following drugs acts directly on the body’s receptors to produce its effects?

Epinephrine Signup and view all the answers

Which drug increases the release of natural chemicals in the body instead of directly acting on receptors?

Amphetamine Signup and view all the answers

Ephedrine is an example of a dual-acting sympathomimetic because it:

Acts both directly on receptors and increases chemical release Signup and view all the answers

Why do catecholamines have poor penetration into the CNS?

They are polar Signup and view all the answers

Sympathomimetics primarily work by stimulating which part of the nervous system?

Sympathetic Nervous System Signup and view all the answers

Which structural component is essential for a drug to be classified as a catecholamine?

Benzene ring with OH groups at positions 1 and 5 Signup and view all the answers

What is a key characteristic of noncatecholamines compared to catecholamines?

They typically have a longer half-life. Signup and view all the answers

Which neurotransmitter's effects are blocked by antiadrenergic drugs?

Norepinephrine Signup and view all the answers

Which receptors are directly stimulated by sympathomimetics like epinephrine?

Alpha and Beta receptors Signup and view all the answers

How does cocaine function as an indirect-acting sympathomimetic?

By blocking the reuptake of norepinephrine Signup and view all the answers

What describes the mechanism of action for dual-acting sympathomimetics like ephedrine?

They stimulate adrenergic receptors and increase norepinephrine release. Signup and view all the answers

Which process primarily inactivates catecholamines in the body?

Metabolism by MAO and COMT Signup and view all the answers

What determines the polar nature of catecholamines and their ability to cross the blood-brain barrier?

Presence of a catechol group Signup and view all the answers

Which of the following statements is true regarding antiadrenergic drugs?

They block sympathetic nervous system actions. Signup and view all the answers

Which characteristic is generally attributed to catecholamines?

They are quickly metabolized by MAO and COMT. Signup and view all the answers

What is a feature of sympathomimetics in general?

They activate the sympathetic nervous system. Signup and view all the answers

Study Notes

Sympathomimetics

Sympathomimetics mimic the sympathetic nervous system's responses, enhancing the "fight or flight" reaction.
Epinephrine (adrenaline) is the primary example, increasing heart rate and other sympathetic effects.
These drugs primarily stimulate the sympathetic nervous system, distinguishing them from other classes.

Catecholamines

Catecholamines include epinephrine and norepinephrine and share a specific structural component: the 3,4-dihydroxybenzene group.
They are quickly inactivated by enzymes such as monoamine oxidase (MAO) and catechol-O-methyltransferase (COMT) for maintaining homeostasis.
Poor penetration of catecholamines into the central nervous system (CNS) is due to their polar nature, hindering the ability to cross the blood-brain barrier.

Noncatecholamines

Noncatecholamines, like ephedrine, exhibit a longer duration of action compared to catecholamines, as they are not as rapidly broken down by metabolic enzymes.
They typically have a longer half-life and can be better absorbed orally than catecholamines.

Antiadrenergic Drugs

Antiadrenergic drugs decrease the "fight or flight" responses governed by the sympathetic nervous system.
They block the effects of norepinephrine, counteracting sympathetic activation by reducing heart rate and blood pressure.

Direct Acting Sympathomimetics

Direct-acting sympathomimetics, such as epinephrine, work by binding directly to alpha and beta adrenergic receptors to elicit physiological responses.
This direct action distinguishes them from other sympathomimetics that may primarily influence the release of neurotransmitters.

Indirect Acting Sympathomimetics

Indirect acting sympathomimetics, like amphetamines, increase the release of natural neurotransmitters, such as norepinephrine and dopamine, rather than directly binding to receptors.
Cocaine illustrates this action by blocking the reuptake of norepinephrine in the synapse, resulting in prolonged sympathetic effects.

Dual Acting Sympathomimetics

Dual-acting sympathomimetics, such as ephedrine, have both direct receptor activation and enhanced release of norepinephrine, combining the effects of both categories.
This dual action allows for broader therapeutic applications and heightened physiological responses.

Catecholamine Inactivation

The rapid inactivation of catecholamines occurs through metabolism by MAO and COMT in the body, ensuring transient effects suited for physiological responses.

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Description

Test your knowledge on sympathomimetics and catecholamines with this quiz. Explore key concepts including drug classifications, mechanisms of action, and enzyme interactions. Perfect for students studying pharmacology or related health sciences.