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Questions and Answers
Which phase of drug metabolism primarily involves the introduction of small, hydrophilic functional groups to increase water solubility?
Which phase of drug metabolism primarily involves the introduction of small, hydrophilic functional groups to increase water solubility?
What is the primary function of Phase III in drug metabolism?
What is the primary function of Phase III in drug metabolism?
Which of the following represents an oxidation-based enzyme involved in Phase I drug metabolism?
Which of the following represents an oxidation-based enzyme involved in Phase I drug metabolism?
Which transporters are not involved in Phase 0 uptake of drugs?
Which transporters are not involved in Phase 0 uptake of drugs?
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What happens during Phase II of drug metabolism?
What happens during Phase II of drug metabolism?
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Which of the following enzymes is NOT associated with Phase I drug metabolism?
Which of the following enzymes is NOT associated with Phase I drug metabolism?
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What is the primary role of ATP-binding cassette transporters in drug pharmacokinetics?
What is the primary role of ATP-binding cassette transporters in drug pharmacokinetics?
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Which phase of drug metabolism includes enzymes that can catalyze reactions without prior Phase I modifications?
Which phase of drug metabolism includes enzymes that can catalyze reactions without prior Phase I modifications?
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Which functional groups are introduced during Phase I drug metabolism?
Which functional groups are introduced during Phase I drug metabolism?
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What is the consequence of drug metabolism rates depending on doses and administration frequency?
What is the consequence of drug metabolism rates depending on doses and administration frequency?
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What is the primary organ responsible for the metabolism and elimination of xenobiotics in the body?
What is the primary organ responsible for the metabolism and elimination of xenobiotics in the body?
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In the oral route with first pass metabolism, what is the pathway of the drug after ingestion?
In the oral route with first pass metabolism, what is the pathway of the drug after ingestion?
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What is true regarding prodrugs?
What is true regarding prodrugs?
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What is the general impact of drug metabolism on the therapeutic efficacy of the parent drug?
What is the general impact of drug metabolism on the therapeutic efficacy of the parent drug?
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How are drugs that follow the IV route ultimately eliminated from the body?
How are drugs that follow the IV route ultimately eliminated from the body?
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What processes determine the intensity and duration of drug action?
What processes determine the intensity and duration of drug action?
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Which of the following statements about metabolites is correct?
Which of the following statements about metabolites is correct?
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What is the consequence of xenobiotics being ingested orally without first pass metabolism?
What is the consequence of xenobiotics being ingested orally without first pass metabolism?
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Which of the following best defines drug metabolism?
Which of the following best defines drug metabolism?
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What potential effects can drug metabolism have on adverse drug reactions?
What potential effects can drug metabolism have on adverse drug reactions?
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What is a characteristic feature of Phase II in drug metabolism?
What is a characteristic feature of Phase II in drug metabolism?
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Which of the following statements is true regarding Phase 0 of drug metabolism?
Which of the following statements is true regarding Phase 0 of drug metabolism?
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What type of enzymes is primarily responsible for reduction reactions in Phase I drug metabolism?
What type of enzymes is primarily responsible for reduction reactions in Phase I drug metabolism?
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Which phase of drug metabolism may occur without the need for prior Phase I metabolism?
Which phase of drug metabolism may occur without the need for prior Phase I metabolism?
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Which of the following transporters are known to be involved in Phase III drug metabolism?
Which of the following transporters are known to be involved in Phase III drug metabolism?
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What is the consequence of drug metabolism on the rate of adverse drug reactions (ADRs)?
What is the consequence of drug metabolism on the rate of adverse drug reactions (ADRs)?
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Which description best fits the enzymes belonging to the oxidation-based category in Phase I drug metabolism?
Which description best fits the enzymes belonging to the oxidation-based category in Phase I drug metabolism?
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How do ATP-binding cassette transporters primarily function in drug metabolism?
How do ATP-binding cassette transporters primarily function in drug metabolism?
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In which cellular location are the majority of Phase II drug-metabolizing enzymes found?
In which cellular location are the majority of Phase II drug-metabolizing enzymes found?
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What is the primary outcome of Phase I metabolism in drug processing?
What is the primary outcome of Phase I metabolism in drug processing?
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What typically happens to most metabolites compared to the parent drug in terms of therapeutic efficacy?
What typically happens to most metabolites compared to the parent drug in terms of therapeutic efficacy?
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In the oral route with first pass metabolism, which sequence correctly describes the pathway after drug absorption?
In the oral route with first pass metabolism, which sequence correctly describes the pathway after drug absorption?
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Which route of drug elimination primarily involves both hepatic and renal metabolism?
Which route of drug elimination primarily involves both hepatic and renal metabolism?
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What is a characteristic of prodrugs regarding their efficacy?
What is a characteristic of prodrugs regarding their efficacy?
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Which of the following best describes xenobiotics?
Which of the following best describes xenobiotics?
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How does drug metabolism influence adverse drug reactions (ADRs)?
How does drug metabolism influence adverse drug reactions (ADRs)?
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What is the primary purpose of metabolic pathways in processing xenobiotics?
What is the primary purpose of metabolic pathways in processing xenobiotics?
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After the first pass metabolism, how is the drug typically excreted from the body?
After the first pass metabolism, how is the drug typically excreted from the body?
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What role does drug metabolism play in determining the duration of drug action?
What role does drug metabolism play in determining the duration of drug action?
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Which of the following statements is true regarding drug metabolism?
Which of the following statements is true regarding drug metabolism?
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Study Notes
Xenobiotics
- Xenobiotics are chemical substances not naturally found in the human body
- These include drugs, pollutants, pesticides, food additives, and synthetic chemicals
- The body processes them through metabolic pathways, primarily in the liver, to detoxify and eliminate them
Major Routes of ADME
Oral Route Without First Pass Metabolism
- Drug is ingested and enters the gastrointestinal tract (GIT)
- Low absorption means the drug mostly stays in the GI tract and is excreted as unmetabolized drug in feces
Oral Route With First Pass Metabolism
- Drug is ingested, enters the GIT, and is absorbed through the intestinal wall
- Travels to the liver via the hepatic portal vein
- Some drug is converted into metabolites in the liver (hepatocytes)
- The mixture of drug and metabolite(s) travels to target organs via the hepatic vein
- Excreted via urine or feces (as a mixture of the original drug and metabolites)
IV Route
- Drug enters the body intravenously
- Enters systemic circulation
- Travels to the liver and kidneys for hepatic and renal metabolism
- Eliminated via urine or bile
The Routes of Drug Elimination
- Shows the percentage of primary elimination routes (Hepatic, Renal, and Unknown)
- Provides a breakdown of the roles of P450 enzymes in metabolism (e.g., 3A4/5 is involved)
- Demonstrates pathways involved in drug metabolism based on percentages
Definition of Drug Metabolism
- Drug metabolism is the process by which the body chemically alters drugs into metabolites
- Metabolites often have lower therapeutic efficacy than the parent drug
- Metabolism helps to deactivate drugs and make them more water-soluble for excretion
Impact of Drug Metabolism
- Drug metabolism reactions influence the intensity and duration of drug action, playing a role in detoxification and toxification
- Drug metabolism rates are often influenced by dosage and frequency of administration
- Affects drug pharmacokinetics (e.g., rates of absorption, distribution, and elimination)
- Effects drug pharmacodynamics (e.g., target binding, duration of action, efficacy, and potency)
- Can influence adverse drug reactions (ADRs) and toxicity either increasing, decreasing, or not changing them
Overview of the Phases of Drug Metabolism
Phase 0
- Involves cellular uptake of drugs by membrane-bound transporters.
Phase I Drug-Metabolizing Enzymes
- Oxidation-Based Enzymes: Cytochrome P450 (CYP), Flavin-containing monooxygenase (FMO), Alcohol dehydrogenase (ADH), Aldehyde dehydrogenase (ALDH), Molybdenum hydroxylase (AOX & XDH), Monoamine oxidase (MAO)
- Reduction-Based Enzymes: Aldo-keto reductase (AKR), Quinone oxidoreductase (NQO), Dihydropyrimidine dehydrogenase (DPYD)
- Hydrolysis-Based Enzymes: Carboxylesterase (CES), Paraoxonase (PON), Epoxide hydrolase (EPHX)
Phase II Drug-Metabolizing Enzymes
- UDP-glucuronosyltransferases (UGTs)
- Sulfotransferases (SULTs)
- Glutathione s-transferases (GSTs)
- N-acetyltransferases (NATs)
- Methyltransferases (TPMT, COMT)
Phase 0 Uptake Transporters
- Organic anion transporters (OATs)
- Organic anion transporting polypeptides (OATPs)
- Organic cation transporters (OCTs)
- Solute carrier organic anion transporters (SLCOs)
Phase III Efflux Transporters
- ATP-binding cassette transporters (ABCs)
- P-glycoprotein (P-gp)
- Multidrug resistance 1 (MDR1, ABCB1)
- Multidrug resistance-associated protein 2 (MRP2, ABCC2)
- Breast cancer resistance protein (BCRP, ABCG2)
- Solute carrier transporters (SLCOs)
Subcellular Location of ADME Proteins
- Cell membrane: All uptake and efflux transporters
- Endoplasmic reticulum: Phase I enzymes (P450, FMO, NQO, EPHX) and some Phase II enzymes (UGTs, GSTs, TPMT)
- Cytosol: Phase I enzymes (AOX, NQO, EPHX, AHD, ALDH), some Phase II enzymes (GSTs, SULTS, NATs, TPMT)
- Mitochondria: Phase I enzymes (MAO, ALDH2) and some Phase II enzymes (NATs)
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Description
Explore the fascinating world of xenobiotics, chemical substances not naturally found in the human body. This quiz delves into various routes of absorption, distribution, metabolism, and excretion (ADME), focusing on the mechanisms by which the body processes these substances. Test your knowledge on the oral and intravenous routes and their effects on drug metabolism.
