Pharmacology Drug Metabolism Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary purpose of drug metabolism in the body?

To increase the potency of xenobiotics

To eliminate all toxicity from drugs

To convert drugs into water-soluble metabolites for excretion (correct)

To prolong the activity of active drugs

Which of the following correctly describes the biological effects of drug metabolism?

Both the drug and its metabolite are always biologically active

All metabolites possess greater biological effects than the original drug

Drug metabolism has no impact on biological activity

The observed biological activity can also be caused exclusively by the metabolite in the case of prodrugs (correct)

What role does drug metabolism play in the excretion of substances?

It solely focuses on increasing the biological activity of drugs

It prevents the excretion of any metabolite

It decreases the rate of excretion by making drugs more lipophilic

It enhances the elimination of xenobiotics by transforming them into water-soluble forms (correct)

What happens to prodrugs during drug metabolism?

They often convert into active metabolites that exert biological effects Signup and view all the answers

Which statement about the biological role of drug metabolism is incorrect?

All drugs undergo biotransformation to increase their biological activity Signup and view all the answers

What metabolic reaction is responsible for converting amphetamine into an inactive form?

Deamination Signup and view all the answers

Which drug is considered a pro-drug that gets converted into an active form in the body?

Prontosil Signup and view all the answers

Which of the following is true about non-metabolic drugs?

They are highly hydrophilic. Signup and view all the answers

What is the main pharmacological effect of trichloroethanol, the metabolite of chloral hydrate?

Sedative & hypnotic Signup and view all the answers

Which of the following reactions is involved in the transformation of parathion to paraoxon?

Oxidation Signup and view all the answers

Which drug is produced from the N-dealkylation of ipronazid?

Isoniazid Signup and view all the answers

What is the effect of the drug 'phenobarbital' after being converted from primidone?

Acts as an antiepileptic Signup and view all the answers

Which process is primarily involved in the pharmacological activation of chlorpromazine?

S-Oxidation Signup and view all the answers

Which of the following is not a feature of metabolically stable drugs?

Easy metabolic conversion Signup and view all the answers

What type of reaction would you consider if a drug is converted into another active drug instead of being inactivated?

Bioactivation Signup and view all the answers

What is the primary reaction involved in dealkylation as depicted?

Oxidation Signup and view all the answers

Which functional group is characterized by the presence of an -OH group?

Alcohol Signup and view all the answers

Which compound structure is depicted in relation to amphetamine's reaction pathway?

Oxidative deamination Signup and view all the answers

In the context of the CYP450 oxidation reactions, what is a common product of dealkylation involving nitrogen?

Ammonia Signup and view all the answers

What is the significance of hydroxylation in CYP450 reactions?

It adds a hydroxyl group to an aromatic ring. Signup and view all the answers

Which type of derivative is mentioned as undergoing oxidation reactions?

3-Halogenated aliphatic derivatives Signup and view all the answers

What is the role of alkyl groups in the context of dealkylation?

To serve as leaving groups Signup and view all the answers

What mechanism is likely involved in the oxidative reaction of amphetamines?

Free radical mechanism Signup and view all the answers

What characterizes soft drugs?

They metabolize predictably to non-toxic products. Signup and view all the answers

What is the definition of bioavailability of a drug?

The fraction of the dose found in circulation. Signup and view all the answers

Which of the following is NOT a Phase I metabolic reaction?

Glucuronidation Signup and view all the answers

What is the primary role of cytochrome P450 in drug metabolism?

To activate molecular oxygen for oxidative metabolism. Signup and view all the answers

Which factor does NOT influence the bioavailability of a drug?

Cost of manufacturing Signup and view all the answers

Which enzyme is primarily responsible for oxidative metabolism in humans?

Cytochromes P450 Signup and view all the answers

What type of reactions are part of Phase II metabolism?

Glucuronidation and sulfation Signup and view all the answers

Where in the body are cytochrome P450 enzymes predominantly located?

Liver cells Signup and view all the answers

What is the key effect of oxidative desulfuration in the metabolism of thiopental?

Formation of pentobarbital Signup and view all the answers

Which metabolic process is primarily associated with the conversion of ethanol to acetic acid?

CYP2E1 oxidation Signup and view all the answers

In the metabolism of thioridazine, which compound represents a sulfoxide derivative?

Mesoridazine Signup and view all the answers

What type of reaction is predominantly involved in the metabolism of benzodiazepines?

N-dealkylation Signup and view all the answers

Which compound serves as a substrate for CYP450 oxidation reactions in the context of thiocarbonyls?

Oxisuran Signup and view all the answers

What is the result of the sulfonation reaction in thiol metabolism?

Formation of sulfone derivatives Signup and view all the answers

What is the significant product of the N-dealkylation of chlordiazepoxide?

Nordazepam Signup and view all the answers

Which compound is associated with increased risk for aplastic anemia during its metabolism?

Halothane Signup and view all the answers

What is a common phase II reaction involving benzodiazepines in metabolism?

Glucuronidation Signup and view all the answers

Which metabolic pathway includes sulfur oxidation of chlorpromazine?

Phase I metabolism Signup and view all the answers

What role does ALDH play in ethanol metabolism?

Converts ethanol to acetic acid Signup and view all the answers

Which of the following is the reactive form of thiol in metabolic reactions?

Thiol Signup and view all the answers

What metabolic change occurs to form a sulfone derivative from thioridazine?

S-oxidation Signup and view all the answers

What is the main toxic effect associated with Chloramphenicol?

Hepatotoxic and nephrotoxic effect Signup and view all the answers

Which of the following compounds is formed from the oxidation reactions involving CYP450?

Epoxide Signup and view all the answers

Which reaction is primarily associated with the hydroxylation process in CYP450 oxidation?

Hydroxylation of unsaturated aliphatic systems Signup and view all the answers

What type of derivatives are formed as a result of the covalent binding to protein from styrene?

Glutathione derivatives Signup and view all the answers

Which derivative is associated with oxamyl chloride?

Mercapturic acid Signup and view all the answers

What is a potential outcome of the hydroxylation of aromatic rings?

Formation of macromolecules Signup and view all the answers

Which of the following compounds is NOT directly related to CYP450 oxidation reactions?

Acetylsalicylic acid Signup and view all the answers

What type of reaction is involved in the ring expansion of α-ethynyl steroids?

Hydroxylation Signup and view all the answers

What is the role of glutathione in the reactions discussed?

Detoxification agent Signup and view all the answers

What type of compounds are styrene reactive epoxides categorized as?

Minor metabolites Signup and view all the answers

Study Notes

Drug Metabolism Overview

Biotransformation of foreign compounds (xenobiotics) occurs in body cells and blood, primarily in the liver.
This process converts xenobiotics into water-soluble derivatives for easier renal elimination.

Movement of Drugs in the Body

Drugs are absorbed from tissues into the bloodstream.
Drugs circulate in the blood, some bound to proteins ("bound drug in blood").
Drugs undergo metabolism, leading to different forms and possible toxicity.
Drugs are then excreted from the body.

Pharmacodynamic Consequences of Metabolism

Some metabolites have no biological effect.
Xenobiotics can have biological effects, differing from medicinal drugs.
Both drugs and metabolites can be biologically active, differing qualitatively or quantitatively.
Biological activity is solely due to the metabolite (prodrugs).

Biological Role of Drug Metabolism

Metabolism can decrease the biological activity of drugs and xenobiotics.
Metabolism can increase excretion by converting drugs into water-soluble metabolites.
Metabolism can activate prodrugs or convert active drugs into different active forms.
It can also generate toxic or carcinogenic metabolites.

Pharmacological Inactivation of Drugs

Processes like oxidative deamination (e.g., amphetamine), aromatic hydroxylation (e.g., phenobarbital), and S-oxidation (e.g., chlorpromazine) lead to drug inactivation.

Drug Toxification

Metabolic reactions can turn active drugs into other active ones (e.g., parathion to paraoxon).
An example is the N-dealkylation. Iproniazid (antidepressant), converted to isoniazid (antituberculosis), demonstrating metabolic activity in pharmaceuticals.

Drug Metabolism Results in Pharmacological Activation

Certain drugs' inactive forms are converted to active ones through metabolism, like chloral hydrate to trichloroethanol which has a prolonged sedative-hypnotic effect.
Primidone is metabolized to phenobarbital, enhancing its antiepileptic effect.

Pro-drug Conversion

Prontosil is converted to sulfanilamide, exhibiting antibacterial activity.
Azo-reduction is a key step in the conversion.

Non-metabolic drugs (hard drugs)

These are metabolically stable hard drugs.
They are highly hydrophilic or lipophilic.
These drugs do not penetrate or contact enzymes and are shielded from metabolic attack.

Soft Drugs

Soft drugs undergo predictable metabolism, leading to non-toxic products after therapeutic effects.

Bioavailability of Drugs

Bioavailability measures the fraction of a drug dose in general circulation.
Bioavailability depends on factors like ADME (absorption, distribution, metabolism, and excretion) and the body's physiological state.

Drug Metabolism Phases

Metabolism is divided into two phases, I and II.
Phase I generally modifies the drug, while Phase II conjugates the drug to increase water solubility.
Phase I reactions like oxidation, reduction, hydrolysis, hydration, and isomerization are important steps.

Phase II Reactions

Examples of Phase II reactions include glucuronidation, sulfation, acetylation, methylation, glutathione, amino acid, and fatty acid conjugations.

Phase I Metabolism: Cytochromes P450

Cytochromes P450 are the major mixed-function oxidases in the liver.
They catalyze the oxidative metabolism of many drugs and substrates.
These enzymes are major players in drug metabolism.
These enzymes are primarily found in the liver but are also found in other organs, involved in a wide variety of metabolic steps.
Functional polymorphism exists in several CYP450s. (CYP2A6, CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4/5).

I- CYP450 Oxidation Reactions—Hydroxylation

Explains different types of hydroxylation reactions, including saturated aliphatic carbons, aromatic rings, activated carbons, 1-ethers, and aliphatic rings.
Various drug examples (testosterone, valproic acid, secobarbital, phenacetin, nitrobenzene) are mentioned to illustrate the diverse substrates CYP450 can act on.

I- CYP450 Oxidation Reactions—Other Reactions

Includes aliphatic ring hydroxylation, hydroxylation at activated carbons (e.g., phenacetin), and oxidation of unsaturated aliphatic systems (e.g., styrene).
Examples like diethylstilbestrol, aromatic hydroxylation, metabolism of benzene, and p-hydroxylation of nitrobenzene also fall under this category.
More examples relating to benzo[a]pyrene, carbamazepine, and others highlight specific scenarios impacting health.

I- CYP450 Oxidation Reactions—N-Oxidation

Explains the process involving 3ry amines, 1ry and 2ry amines, and amides, providing examples like bromopheniramine, amphetamine, and also mentioning other types that fall under this specific category.

I- CYP450 Oxidation Reactions—S-Oxidation

Focuses on thiols, thioethers, and thiocarbonyls for S-containing drugs.
Expands on examples such as oxisuran, thioridazine, and thiopental.

I- CYP450 Oxidation Reactions—Multiple Phase I Metabolic Pathways

Explains various examples of multiple phase I metabolic pathways, such as those involved in chloropromazine, highlighting different steps and resulting metabolites. (oxidation, N-demethylation, ring hydroxylation, sulfur oxidation).

Ethanol Oxidation to Acetic Acid

Details the different enzymes and steps in the breakdown of ethanol, involving microsomes (CYP2E1), alcohol dehydrogenase (cytosolic), and catalase (peroxisomes). This illustrates a different aspect of metabolism related to a toxic substance.

Multiple Phase 1 metabolic Pathway for Benzodiazepines (BZPs)

Outlines multiple metabolic pathways for benzodiazepines, encompassing hydroxylation, dealkylation, and oxidative deamination.
This showcases diverse enzymatic pathways on a specific pharmacological class.

Dehalogenation Reactions Catalyzed by Cytochrome P450

Describes dehalogenation reactions, involving Halothane and emphasizing the potential for protein binding and aplastic anemia.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on drug metabolism and its biological effects. This quiz covers the primary purposes, roles in excretion, prodrugs, and metabolic reactions involved in drug conversion. Enhance your understanding of pharmacology with these key concepts.