Antihyperlipidemic Drugs Mechanism of Action (MOA) Quiz and Flashcards

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Questions and Answers

What is the impact of the substituent R1 in fibric acid derivatives on the drug's activity?

It reduces oral absorption

It increases the drug's anionic activity

It determines whether the drug is a prodrug or an active drug (correct)

It prolongs bleeding time

What is the role of esters in fibric acid derivatives?

To reduce flushing and GI distress

To increase lipolysis of stored triglycerides

To decrease liver triglyceride esterification

To be anionic for activity, as esters are prodrugs (correct)

What is the primary effect of phase 2 conjugation on niacin?

It converts active niacin into a metabolite (correct)

It increases lipolysis of stored triglycerides

It reduces VLDL particle size

It inhibits the formation of HDL

What is the main reason for fibric acid derivatives to be anionic for activity?

To ensure their activity, as anions are required for their effectiveness Signup and view all the answers

What is the impact of extended release formulations on niacin's side effects?

They significantly reduce flushing Signup and view all the answers

What is the function of a prodrug?

To require hydrolysis by esterase to become the active drug Signup and view all the answers

Which type of statin exhibits ring cyclization to create lactone, making it a prodrug?

Lovastatin Signup and view all the answers

What is the significance of affinity for the enzyme in statins?

It affects the binding with CoA-SH area Signup and view all the answers

What is the role of HMG-CoA in the context of statins?

It is a target of competitive antagonists like statins Signup and view all the answers

Which characteristic accounts for the high affinity of statins for the enzyme?

Ring system with lipophilic substituents Signup and view all the answers

What is the role of esterases in the metabolism of statin pro-drugs?

They convert the pro-drugs into their active acid metabolites Signup and view all the answers

Which cytochrome P450 enzyme is responsible for metabolizing lovastatin, simvastatin, and atorvastatin?

CYP3A4 Signup and view all the answers

What effect does naringin in grapefruit juice have on CYP3A4?

It inhibits CYP3A4 Signup and view all the answers

Which statin is resistant to CYP3A4 but is oxidized in the gut/liver?

Pravastatin Signup and view all the answers

Why are lipophilic groups important for the transport of drug molecules into the liver?

They can be passively transported across barriers Signup and view all the answers

What is the defining characteristic that makes a drug a prodrug?

It undergoes conversion into the active drug in the body Signup and view all the answers

Why does the presence of R2 as an ester make a compound a prodrug?

Esters are converted into the active drug in the body Signup and view all the answers

Which of the following best describes the role of R2 in determining whether a compound is a prodrug or an active drug?

R2 undergoes conversion to release the active drug Signup and view all the answers

What is the main difference between gemfibrozil and fenofibrate in terms of being an active drug?

Gemfibrozil is metabolized into an active drug, while fenofibrate is already an active drug Signup and view all the answers

How does the conversion of a prodrug into an active drug typically impact its pharmacological activity?

It enhances its pharmacological activity Signup and view all the answers

Which mechanism best explains the decreased formation of LDLs in plasma due to a particular drug action?

Reducing VLDL particle size Signup and view all the answers

How does the drug interaction between niacin and anticoagulants impact the patient?

Prolongs the bleeding time Signup and view all the answers

What is the major impact of extended release formulations on niacin's side effects?

Significant reduction in flushing Signup and view all the answers

What is the impact of naringin in grapefruit juice on CYP3A4?

It inhibits CYP3A4, reducing the metabolism of statins Signup and view all the answers

How does the resistance of pravastatin to CYP3A4 impact its metabolism?

It allows pravastatin to be oxidized in the gut/liver Signup and view all the answers

What characteristic of statins contributes to their metabolism by CYP3A4 and 2C9?

The presence of lactone ring and esterases promotes CYP3A4 and 2C9 metabolism Signup and view all the answers

How do bile sequestrants interact with anionic drugs such as NSAIDS and anticoagulants?

They tend to bind anionic drugs, reducing their absorption Signup and view all the answers

What is the recommended timing for taking most drugs in relation to cholestyramine or colestipol?

2 hours apart from taking cholestyramine or colestipol Signup and view all the answers

How do bile sequestrants affect the absorption of digoxin and tricyclic antidepressants?

They tend to bind these drugs, reducing their absorption Signup and view all the answers

What is the general drug interaction pattern of bile sequestrants with regard to HMG-CoA reductase inhibitors?

They tend to bind HMG-CoA reductase inhibitors, reducing their absorption Signup and view all the answers

Which characteristic of HMG-CoA reductase is responsible for its membrane-bound nature?

N-domain Signup and view all the answers

What specific feature of HMG-CoA reductase binds to the co-enzyme NADPH?

S-domain Signup and view all the answers

What is the role of the cis loop in HMG-CoA reductase?

Participates in the catalytic site Signup and view all the answers

Which characteristic of fibric acid derivatives impacts their oral absorption?

The lipophilicity of the R1 substituent Signup and view all the answers

Which factor makes anionic groups crucial for the activity of fibric acid derivatives?

Enhances binding to lipoproteins Signup and view all the answers

How does the presence of lipophilic substituents impact the absorption of fibric acid derivatives?

It promotes distribution into adipose tissue, reducing systemic bioavailability Signup and view all the answers

Which characteristic of R2 in the context of fibric acid derivatives makes it a prodrug?

Introduction of an ester group Signup and view all the answers

Why is gemfibrozil or fenofibrate considered an active drug?

Thanks to the activation of peroxisome proliferator-activated receptor alpha (PPARa) Signup and view all the answers

What effect does the presence of a bulky alkyl group have on the lipophilicity of fibric acid derivatives?

Increases lipophilicity Signup and view all the answers

How does the formation of a prodrug impact the lipophilicity of fibric acid derivatives?

Reduces lipophilicity Signup and view all the answers

Study Notes

Fibric Acid Derivatives

The substituent R1 in fibric acid derivatives affects the drug's activity, with its presence or absence influencing the compound's potency.
Esters play a crucial role in fibric acid derivatives, as they can be converted into active drugs through esterase-mediated hydrolysis.
The anionic nature of fibric acid derivatives is essential for their activity, with the presence of anionic groups facilitating their binding to the target enzyme.

Niacin

Phase 2 conjugation of niacin results in its primary effect, which is the formation of a water-soluble glucuronide conjugate.
Extended release formulations of niacin reduce its side effects, such as flushing and pruritus.

Prodrugs

A prodrug is a compound that is converted into an active drug through enzymatic or chemical reactions.
The presence of esters (R2) in a compound makes it a prodrug, as it requires esterase-mediated hydrolysis to become active.

Statins

The primary mechanism of statins involves the inhibition of HMG-CoA reductase, a rate-limiting enzyme in the cholesterol biosynthesis pathway.
The high affinity of statins for the enzyme is attributed to their lipophilic nature and ability to bind to the active site.
Esterases play a crucial role in the metabolism of statin prodrugs, converting them into active drugs.
Lovastatin, simvastatin, and atorvastatin are metabolized by the cytochrome P450 enzyme CYP3A4.
Pravastatin is resistant to CYP3A4 metabolism, but is oxidized in the gut and liver.
Lipophilic groups are essential for the transport of statin molecules into the liver, where they can exert their pharmacological activity.

Drug Interactions

Naringin in grapefruit juice inhibits CYP3A4, leading to increased levels of statins and other drugs metabolized by this enzyme.
Bile sequestrants, such as cholestyramine and colestipol, interact with anionic drugs like NSAIDs and anticoagulants, reducing their absorption.
The recommended timing for taking most drugs in relation to bile sequestrants is to take them one hour before or four hours after administration.
Bile sequestrants affect the absorption of digoxin and tricyclic antidepressants, leading to reduced efficacy.
The general drug interaction pattern of bile sequestrants with regard to HMG-CoA reductase inhibitors is a reduction in the absorption of statins.

HMG-CoA Reductase

The enzyme is membrane-bound, with a hydrophobic domain responsible for its association with the membrane.
The specific feature of HMG-CoA reductase that binds to the co-enzyme NADPH is the cis loop.
The cis loop is essential for the enzyme's catalytic activity, facilitating the reduction of HMG-CoA to mevalonate.

Fibric Acid Derivatives (continued)

The presence of lipophilic substituents in fibric acid derivatives affects their oral absorption, with more lipophilic compounds exhibiting improved absorption.
The anionic nature of fibric acid derivatives is crucial for their activity, as it facilitates their binding to the target enzyme.
The presence of a bulky alkyl group in fibric acid derivatives reduces their lipophilicity, affecting their absorption and activity.
The formation of a prodrug in fibric acid derivatives affects their lipophilicity, making them more or less lipophilic depending on the substituent.

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Test your knowledge about the mechanism of action of antihyperlipidemic drugs with this quiz. Explore how these drugs inhibit lipolysis, decrease plasma lipids, reduce VLDL particle size, and increase HDL formation.

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