Chapter 4 - Xenobiotic Transformation Flashcards
All of the following are true of CYP2D6 except…
A. It converts codine to morphine
B. It is polymorphic
C. It is induced by quinidine
D. Poor metabolizers have a lower risk of lung cancer
C. It is induced by quinidine
A probe drug for human CYP2C19 is…
A. Mephenytoin
B. Valproic acid
C. Carbamazepine
D. Warfarin
A. Mephenytoin
Aryl hydrocarbon receptor agonists include all of the following except…
A. TCDD
B. Benzopyrene
C. 3-methylcholanthrene
D. Benzene
D. Benzene
Enzyme induction in humans has been asso w/…
A. Osteomalacia
B. Hepatocellular carcinoma
C. Cirrhosis
D. Psoriasis
D. Psoriasis
In metabolism-dependent inhibition of cytochrome P450…
A. The parent compound is a potent inhibitor
B. The metabolite must be a product of P450 catalysis
C. The metabolite is a potent inhibitor
D. The inhibition is always irreversible
C. The metabolite is a potent inhibitor
A compound that induces CYP2D6 is…
A. Rifampin
B. Dexamethazone
C. Ethanol
D. None of the above
D. None of the above
All of the following are considered phase I biotransformation reactions except…
A. Hydrolysis
B. Conjugation
C. Reduction
D. Oxidation
B. Conjugation
All of the following statements are true except…
A. Forms of epoxide hydrolase can exist in both microsomes and cytosol
B. Gemfibrozil is conjugated with glucuronic acid before it is oxidized by cytochrome P450
C. CYP2D6 and CYP2D9 metabolize over half the drugs in current use
D. Biotransformation can take place in the gut
C. CYP2D6 and CYP2D9 metabolize over half the drugs in current use
UDP glucuronyltransferases conjugate all of the following endogenous molecules except…
A. Thyroid hormone
B. Bilirubin
C. Steroid hormones
D. Parathyroid hormone
D. Parathyroid hormone
If codine were given to a patient who was 2D6 ultrametabolizer, the most likely result would be…
A. Inadequate analgesia
B. Higher than normal levels of morphine at 2 hrs postdose
C. Higher than normal levels of codine at 4 hrs postdose
D. Higher than normal levels of oxycodone at 4 hrs postdose
B. Higher than normal levels of morphine at 2 hrs postdose
A victim drug is…
A. A drug whose clearance is determined mostly by a single route of elimination
B. A drug that induces neutralizing antibodies
C. A drug that is unstable in plasma
D. A racemic drug mixture where one isomer inhibits the metabolism of the other isomer
A. A drug whose clearance is determined mostly by a single route of elimination
Terfenadine and ketoconazole are examples of…
A. Enzyme inducers
B. Perpetrator and inhibitor
C. Victim drug and perpetrator
D. Drugs with limited biotransformation
C. Victim drug and perpetrator
All of the following are true except…
A. Hyperforin induces CYP3A4
B. Broccoli inhibits 1A2
C. Grapefruit juice inhibits intestinal CYP3A4
D. Drugs that inhibit transporters can help anticancer agents
B. Broccoli inhibits 1A2
Levels of UDPGA and PAPS are lowered by…
A. Saint John’s wort
B. Phenobarbital
C. Rifampin
D. Fasting
D. Fasting
An example of a pair of enantiomers in which one inhibits CYP2D6 and the other has little activity is…
A. R and S methadone
B. R and S warfarin
C. R and S mephenytoin
D. Quinidine and quinine
D. Quinidine and quinine
Which of the following biotransformation enzyme-subcellular location pairs is correct…
A. Alkaline phosphatase-cell membrane
B. Carboxyesterase-blood
C. Sulfotransferase-cytosol
D. All of the above
D. All of the above
The least likely biotransformation reaction that aniline would undergo is…
A. Halogenation
B. Aromatic hydroxylation
C. N-acetylation
D. N-glucuronidation
A. Halogenation
The proteins KEAP1 and Nrf2…
A. Suppress CYP expression in response to inflammation
B. induce enzymes in response to oxidative stress
C. Promotes DNA methylation
D. None of the above
B. induce enzymes in response to oxidative stress
All of the following are true of glutathione except…
A. Germ cells and ovum have high levels
B. Conjugation of dibromoethane results in a mutagenic metabolite
C. Conjugation of electrophiles is a major means of protecting DNA
D. Conjugation always occurs enzymatically
D. Conjugation always occurs enzymatically
Phenobarbital…
A. Causes liver tumors in humans and rodents
B. Causes liver tumors in rodents but not humans
C. Causes liver tumors in primates but not rodents
D. Causes liver tumors in rodents and nasal tumors in humans
B. Causes liver tumors in rodents but not humans
All of the following are hydrolytic enzymes except…
A. Carboxyesterase
B. Alcohol dehydrogenase
C. Cholinesterase
D. Paraoxonase
B. Alcohol dehydrogenase
All of the following are true of epoxide hydrolases except…
A. They add oxygen to a double bond and form a 3- member ring
B. They are important in detoxifying electrophiles
C. They play a role in converting benzo(a)pyrene to a carcinogen
D. Some forms are inducible
A. They add oxygen to a double bond and form a 3- member ring
Nitroreductase plays an important role in…
A. Nasal epithelium
B. Lung Clara cells
C. White blood cells
D. Intestinal microflora
D. Intestinal microflora
A drug that undergoes sulfoxide reduction is…
A. Haloperidol
B. chloramphenicol
C. Thalidomide
D. Sulindac
D. Sulindac
Under low oxygen tensions, reduction reactions can be catalyzed by…
A. Cytochrome P450
B. NADPH quinine oxioreductase
C. Cytosolic aldehyde oxidase
D. All of the above
D. All of the above
Quinine oxioreductases are thought to play a protective role in…
A. Liver toxicity of microcystin
B. Bone marrow toxicity of benzene
C. Renal toxicity of aminoglycosides
D. Neurotoxicity of n-hexane
B. Bone marrow toxicity of benzene
All of the following are mechanisms for removing halogen atoms from aliphatic xenobiotics except…
A. Grignard dehalogenation
B. Reductive dehalogenation
C. Oxidative dehalogenation
D. Double dehalogenation
A. Grignard dehalogenation
Oxidation of ethanol to acetaldehyde takes place in…
A. Cytosol
B. Microsomes
C. Peroxisomes
D. All of the above
D. All of the above
Reductive dehalogenation of carbon tetrachloride produces…
A. Phosgene
B. chloroform
C. Trichloromethyl radical
D. Hydrochloric acid
C. Trichloromethyl radical
Acetaldehyde is converted to acetic acid by ALDH2 in…
A. Mitochondria
B. cytosol
C. Microsomes
D. All of the above
A. Mitochondria
Aldehyde oxidase and xanthene oxioreductase contain…
A. Zinc
B. Molybdenum
C. Selenium
D. Copper
B. Molybdenum
The major metabolite of nicotine excreted into the urine is..
A. Nicotinamide
B. Nicotine glucuronide
C. Cotinine
D. Niacin
C. Cotinine
All of the following are true of myloperoxidase (MPO) except…
A. It is present in neutrophils
B. It can be induced by cyanide ion
C. It forms reactive metabolites of drugs that cause agranulocytones
D. It is polymorphic
B. It can be induced by cyanide ion
Patients with Parkinson’s disease have elevated levels of which of the following enzymes in the substantia nigra region of the brain…
A. COMT
B. Aldehyde oxidase
C. CYP2E1
D. MAO-B
D. MAO-B
All of the following are true of prostaglandin H synthase (PHS) enzymes except..
A. They are known a COX1 and COX 2
B. They convert xenobiotics to carcinogenic metabolites
C. They can be inhibited by drugs
D. They mainly cause toxicity in tissues that contain a high concentration of cytochrome P450
D. They mainly cause toxicity in tissues that contain a high concentration of cytochrome P450
The reactions catalyzed by flavin monooxygenases are most similar to those catalyzed by…
A. MAO-A
B. Cytochrome P450
C. UDP-glucuronyltransferase
D. Xanthine oxidase
B. Cytochrome P450
The highest level of cytochrome P450 are fond in liver…
A. Endoplasmic reticulum
B. Cytosol
C. Mitochondria
D. Peroxisomes
A. Endoplasmic reticulum
All of the following are true of cytochrome P450 except…
A. It places on oxygen atom in a water molecule
B. It does not interact directly with NADPH
C. It strongly binds carbon dioxide
D. During catalytic activity, it directly binds substrate and oxygen
C. It strongly binds carbon dioxide
All of the following are substrates for CYP450 epoxidation except…
A. Coumarin
B. Chlorobenzene
C. Carbemazepine
D. Chloroform
D. Chloroform
All of the following are substrates for CYP450 heteroatom oxygenation except…
A. Toluene
B. NNK
C. Omeprazole
D. Lansoprazole
A. Toluene
All of the following parent-toxic metabolite pairs are correct except…
A. Diclofenac-acyl glucuronide
B. Ethanol-acetic acid
C. Halothane-trifluoroacetylchloride
D. Acetaminophen-N-acetyl-p-benzoquinone imine
B. Ethanol-acetic acid
Which of the following reactions could be mediated by cytochrome P450
A. Hydration of an epoxide
B. Breaking of a hydrogen bond
C. Cleavage of a peptide bond
D. Dehydrogenation
D. Dehydrogenation
All of the following are substrates that are converted by glutathione transferase to more toxic molecules except…
A. Dichloromethane
B. Dibromoethane
C. Aflatoxin B1 8,9 epoxide
D. Hexachlorobutadiene
C. Aflatoxin B1 8,9 epoxide
Human glutathione transferase enzymes are present in..
A. Cytosol
B. microsomes
C. Mitochondria
D. All of the above
D. All of the above
GSTP polymorphisms in humans can influence…
A. Response to chemotherapy
B. Susceptibility to cancer-causing agents
C. Probability of developing asthma
D. All of the above
D. All of the above
Thiosulfate sulfurtransferase (rhodanese) is a major enzyme involved in the detoxification of…
A. Hydrogen peroxide
B. Hydrogen sulfide
C. Hydroxyl radical
D. Nitrous oxide
B. Hydrogen sulfide
Thiosulfate sulfurtransferase polymorphisms may play a role in…
A. Cirrhosis and pulmonary function
B. Dementia and multiple sclerosis
C. Congestive heart failure and rhabdomyolysis
D. Ulcerative colitis and amyotrophic lateral sclerosis
D. Ulcerative colitis and amyotrophic lateral sclerosis
All of the following are true of amino acid conjugates of xenobiotics except…
A. Glycine, glutamine and taurine usually from an amide linkage
B. Aromatic hydroxylamines can react with carboxylic acid groups of serine and proline
C. They are eliminated primarily in the bile
D. Acetyl CoA can be involved
C. They are eliminated primarily in the bile
All of the following are true for glutathione transferaces except…
A. A stereoselective conjugation will most likely occur non-enzymatically
B. They are present within the hepatocyte at high concentrations
C. They are a family of enzymes
D. They are present in most tissue
A. A stereoselective conjugation will most likely occur non-enzymatically
An example of a substrate for a glutathione displacement reaction is…
A. 1,2-dichloro-4-nitrobenzene
B. 1-chloro-2,4-dinitrobenzene
C. Trinitrobenzene
D. All of the above
D. All of the above
An example of a substrate for a glutathione addition reaction is…
A. Hexane
B. 2-propanol
C. b-propiolactone
D. Formic acid
C. b-propiolactone
Glutathione conjugates can end up in the urine as…
A. Mercapturic acid
B. Glucuronic acid
C. Glutaric acid
D. All of the above
A. Mercapturic acid
All of the following compounds can undergo O, N or S methylation except…
A. Acetone
B. Nicotine
C. L-dopa
D. 6-mercaptopurine
A. Acetone
An example of a transesterification reaction is…
A. Methyldopa to 3-O-methyl dopa
B. 4-hydroxyestradiol to O-methyl-4-hydroxyestradiol
C. Cocaine to ethyl cocaine
D. Histamine to N-methylhistamine
C. Cocaine to ethyl cocaine
All of the following statements are true regarding acetylation reactions except…
A. It increases the water solubility of almost all molecules
B. It is a major route of biotransformation of aromatic amines
C. It is a major route of biotransformation of hydrazines
D. It requires the cofactor acetyl CoA
A. It increases the water solubility of almost all molecules
N-acetyltransferases are located in the…
A. Microsomes
B. Cytosol
C. Mitochondria
D. Peroxisomes
B. Cytosol
Slow acetylators of NAT demonstrate all of the following except…
A. Peripheral neuropathy from isoniazid
B. Systemic lupus erythematous from procainamide
C. Peripheral neuropathy from dapone
D. Decreased hypotensive response from hydralazine
D. Decreased hypotensive response from hydralazine
In contrast to glucuronidation, sulfonation is…
A. Low-affinity, low capacity pathway
B. Low-affinity, high-capacity pathway
C. High-affinity, high-capacity pathway
D. High-affinity, low-capacity pathway
D. High-affinity, low-capacity pathway
Induction of sulfotransference enzymes by rifampin may be clinically relevant for…
A. Warfarin
B. Digoxin
C. Ethinyl estradiol
D. All of the above
C. Ethinyl estradiol
All of the following statements regarding sulfonation reaction are true except…
A. They can make a molecule less lipid soluble
B. They always detoxify a molecule
C. Some drugs must be metabolized to a sulfonate conjugate to have a pharmacologic effect
D. Morphine-6-sulfate is more potent than morphine in the rat
B. They always detoxify a molecule
All of the following statements are true regarding methylation except…
A. The process generally decreases the water solubility of the parent
B. The process can mask functional groups that can be metabolized by other conjugation enzymes
C. Inorganic mercury and arsenic can be dimethylated
D. High methyltransferase activity may lower levels of homocysteine
D. High methyltransferase activity may lower levels of homocysteine
All of the following are methyltransferase enzymes except..
A. SAM
B. COMT
C. NNMT
D. HNMT
A. SAM
All of the following are true of glucuronide conjugates of xenobiotics except…
A. They can be excreted in the urine
B. They are formed from activated xenobiotics
C. They are substrates for beta-glucuronidase in the intestinal microflora
D. They can be excreted into bile
B. They are formed from activated xenobiotics
All of the following are true of sulfonation reactions except…
A. They involve the transfer of sulfate
B. They are catalyzed by sulfotransferases
C. The cofactor for the reaction is PAPS
D. They are excreted mainly in the urine
A. They involve the transfer of sulfate
The number of UGT mammalian enzymes that have been identified is approximately…
A. 5
B. 12
C. 22
D. 58
C. 22
Immune hepatitis from NSAIDs may be explained by…
A. Binding of an acyl glucuronide to a protein forming a neoantigen
B. Methylation of DNA and subsequent immune stimulation
C. Cholestasis caused by the sulfinated parent
D. Genetic sensitivity to a portion of the parent molecule
A. Binding of an acyl glucuronide to a protein forming a neoantigen
In addition to the cytoplasm, sulfotransferases are present in mammals in the…
A. Endoplasmic reticulum
B. Mitochondria
C. Plasma membrane
D. Golgi apparatus
D. Golgi apparatus
All of the following statements are true except…
A. CYP3A4 is induced by CAR and PXR agonists
B. AhR is expressed only in human liver and small intestines
C. Highly chlorinated chemicals are resistant to metabolism
D. AhR partners with ARNT to induce CYP1A1 and CYP1A2
B. AhR is expressed only in human liver and small intestines
Most conjugation reactions occur in the…
A. Mitochondria
B. Peroxisome
C. Cytosol
D. Cell membrane
C. Cytosol
An example of a metabolite of conjugation that is more potent than the parent is…
A. Oxazepam glucuronide
B. Propofol glucuronide
C. Morphine-6-glucuronide
D. Thyroxine glucuronide
C. Morphine-6-glucuronide
All of the following are true of UGT enzymes except…
A. They are inducible
B. They can use UDP-glucose as a substrate
C. They are present in many tissues
D. They are more subject to inhibiting drug-drug interactions than CYP450 enzymes
D. They are more subject to inhibiting drug-drug interactions than CYP450 enzymes
All of the following statements are true except…
A. Acyl glucuronides of NSAIDs can be toxic
B. Glucuronide metabolites of aromatic amines can decompose in acid to produce tumorigenic chemicals
C. Crigler-Najjar syndrome is due to a defect in bilirubin conjugation
D. Gilberts disease is due to increased glucuronidation of endogenous substrates
D. Gilberts disease is due to increased glucuronidation of endogenous substrates
Which of the following statements is true of CYP3A4?
A. It is affected more by genetic polymorphisms than environmental factors
B. It can bind 2 substrates at once
C. It is induced by ethyl alcohol
D. None of the above
B. It can bind 2 substrates at once
A human probe for CYP2E1 is…
A. Dextromethorphan
B. Erythromycin
C. Chlorozoxaone
D. Midazolam
C. Chlorozoxaone
Cytochrome 2E1…
A. Requires cytochrome b5
B. Is inhibited by cimetidine
C. Is induced by 3-methylchloanthrene
D. All of the above
A. Requires cytochrome b5
Inhibitors for human CYP3A4 include all of the following except…
A. Erythromycin
B. Mibefradil
C. Ketoconazole
D. Phenytoin
D. Phenytoin
Substrates for human CYP2E1 include all of the following except…
A. Styrene
B. chloroform
C. Aflatoxin B1
D. Vinyl chloride
C. Aflatoxin B1
Substrates for human CYP3A4 include all of the following except…
A. Lovastatin
B. Sirolimus
C. Halothane
D. Midazolam
C. Halothane
A compound that inhibits CYP2D6 is…
A. Rifampin
B. dexamethasone
C. Ethanol
D. Quinidine
D. Quinidine
What type of reaction would be expected to be catalyzed by flavin monooxygenase…
A. N-dealkylation
B. S-oxygenation
C. O-demethylation
D. S-dealkalation
B. S-oxygenation
All of the following are substrates for CYP450-mediated heteroatom dealkalation except…
A. Caffeine
B. styrene
C. Diazepam
D. Dextromethorphan
B. styrene
An example of oxidative desulfuration is…
A. Parathion to paraoxon
B. imipramine to desipramine
C. Codeine to morphine
D. Enalapril to enalaprilat
A. Parathion to paraoxon
An example of oxidative deamination is…
A. Nitrobenzene to aniline
B. DDT to DDE
C. Benzene to hydroquinone
D. Amphetamine to phenylacetone
D. Amphetamine to phenylacetone
An example of a reaction catalyzed by aldehyde oxidase is…
A. N-hexane to neurotoxic metabolite
B. butylated hydroxytoluene to butylated hydroxyanisole
C. Vanillin to vanillic acid
D. Aflatoxin B1 to toxic metabolite
C. Vanillin to vanillic acid
Activity of cytochrome P450 can be surpressed by all of the following except…
A. Vaccination
B. Hypertension
C. Infection
D. Inflammation
B. Hypertension
Cytochrome P450 activity can be affected by…
A. Foods
B. Social habits (smoking, alcohol)
C. Thyroid disease
D. All of the above
D. All of the above
Cytochome P450-mediated reactions include all of the following except…
A. Ester cleavage
B. Methylation
C. Dehydrogenation
D. Oxidative group transfer
B. Methylation
CYP3A7 is present mostly in…
A. Adult human liver
B. Fetal human liver
C. Rodent liver
D. Human lymphoma cells
B. Fetal human liver
The CYP450 present in the lowest amounts in human liver is…
A. CYP2C9
B. CYP2D6
C. CYP3A4
D. CYP1B1
D. CYP1B1
Which of the following CYP450 enzymes metabolizes many therapeutic drugs and is present in human liver and small intestine?
A. CYP2D6
B. CYP2C9
C. CYP3A4
D. CYP1B1
C. CYP3A4
