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The correct choice is (a) True

Explanation: ELECTROPHILES are the SPECIES which are deficient in a pair of electron. These electrophiles in our body are generated through cytochrome P-450. FREE RADICALS are species containing an odd number of electrons. These may be positively charged, negatively charged or neutral. Free radicals are formed via NADPH cytochrome P-450 REDUCTASE.

The CORRECT answer is (a) The phenomenon of increased DRUG metabolizing ability of enzymes by DRUGS and chemicals

The best explanation: The phenomenon of increased drug metabolizing ability of enzymes by drugs and chemicals is CALLED as enzyme induction and the agents which helps to bring such CHANGES are known as inducers.

The correct answer is (a) True

Explanation: The body’s metabolic SYSTEM does not allow any drug to accumulate or AGGREGATE INSIDE the body. Water soluble agents are excreted via urination. The metabolic system TRANSFORMS the water-insoluble drugs to polar and so that it can easily be urinated.

Correct OPTION is (a) HEME protein, flavoprotein, phosphatidylcholine

The best I can explain: Heme protein helps in oxidizing the substrate, flavoprotein functions as an electron carrier and catalyses the reduction of cytochrome 450 to FERROUS FORM, phosphatidylcholine functions to facilitate electron TRANSFER from NADPH to cytochrome 450.

Right answer is (a) Through cytochrome P-450 system

Explanation: Electrophiles are species deficient in ELECTRON pair. The enzyme system through which they are generated is cytochrome-P450. Carbon, nitrogen, SULPHUR COMPOUNDS can be metabolically activated to yield electrophiles.

The correct CHOICE is (d) Competitive inhibition

For EXPLANATION: Competitive inhibition results when structurally similar COMPOUNDS compete for the same site on an enzyme. Such an inhibition due to substrate competition is reversible and can be overcome by a HIGH concentration of one substrate. Methacholine inhibits the metabolism of acetylcholine by competing with it for cholinesterase.

Right CHOICE is (a) Sulfotransferase

The best explanation: Sulfotransferase catalyses the transfer of SULPHATE group from 3’-phosphoadenosine-5’-phosphosulfate to the substrate. It ALSO helps in the LIBERATION of 3’-phosphoadenosine-5’-PHOSPHATE.

The correct choice is (c) In the CYTOPLASM in SOLUBLE form

Explanation: Non-microsomal ENZYMES include those that are present in soluble form in the cytoplasm and those attached to the mitochondria but not to the endoplasmic reticulum. These enzymes are non-specifically catalysing few oxidative reactions, the NUMBER of reductive reactions and hydrolytic reactions.

Correct option is (a) Formation of high REACTIVE metabolites which interact with TISSUES to PRECIPITATE toxic compounds

The explanation: Formation of highly reactive metabolites which can interact with the tissues and precipitate out various toxic compounds such as carcinogens, teratogens, etc. is KNOWN as bioactivation or toxicological ACTIVATION.

Right answer is (b) False

Easy explanation: MATERNAL drug metabolizing ability decreases in the later STAGE of pregnancy. DUE to high LEVELS of steroid hormones in CIRCULATION during pregnancy, in women, the metabolism of promazine and pethidine decreases. Thus, maternal drug metabolizing ability decreases.

Correct choice is (a) 2, 6-Xylidine, N, N-Dimethylglycine

Explanation: The reaction of hydrolysis of amides is catalysed by amidases. Lidocaine is a SECONDARY amide with an ORGANIC substituent on N-atom. THUS providing us with 2, 6-Xylidine, N, N-Dimethylglycine as the end product.

Correct CHOICE is (c) Epoxides

For explanation I WOULD say: Electrophiles are species deficient in electron pair. Important electrophiles are epoxides, hydroxylamines, nitroso, and AZOXY DERIVATIVES, nitrenium IONS, and elemental sulphur.

Right option is (a) True

For EXPLANATION: By research, it has been observed that the ENZYME activity is maximum during the early MORNING and minimum during the late afternoon. This also CORRESPONDS to high and low serum levels of corticosterone.

Right choice is (C) From the activated oxygen P-450 substrate COMPLEX

The best EXPLANATION: One atom of oxygen from the activated oxygen P450 complex is transferred to the substrate to yield the oxidized product and the other atom forms water. The free oxidized FORM of cytochrome P-450 is ready to attach to another MOLECULE of substrate.

The correct choice is (a) Arenols

The best explanation: The oxidation of aromatic CARBON ATOMS proceeds via formation of a reactive intermediate ARENE OXIDE. This arene oxide in most cases is converted into arenols and in some cases produces minor products such as catechols and glutathione conjugates.

Correct choice is (b) False

Easy explanation: Biotransformation of drugs is the conversion of drugs from one CHEMICAL form to ANOTHER. The TERM is used with metabolism. The chemical changes are usually AFFECTED by enzymatically in the body. For example conversion of penicillin to penicilloic acid by bacterial penicillinase.

Right answer is (b) Lipid soluble drugs

To elaborate: The intact Lipoidal membrane of the MICROSOME is essential for its selectivity towards lipid soluble substrates. The lipid soluble SUBSTRATE is bio transformed into water-soluble metabolite by the microsomal ENZYMES and thus can EASILY EXCRETE out.

The correct choice is (B) CHEMICAL drugs which are already found in the body

To elaborate: Soft drugs are natural endogenous substances which are already present in the body. Such as neurotransmitters (dopamine, GABA, EPINEPHRINE, NOREPINEPHRINE), steroids (oxytocin, oestrogen, progesterone), insulin. The body is already programmed to metabolize them and excrete out. THUS these drugs when used are rapidly inactivated.

The correct option is (c) Non-competitive INHIBITION

To explain I WOULD SAY: Non-competitive inhibition happens when structurally different compounds interact with the enzyme and PREVENT the metabolism of the drug. This interaction is not structured SPECIFICALLY. So lead, mercury, arsenic, organophosphorus insecticides inhibit enzymes noncompetitively.

The correct ANSWER is (b) Uridine-5’-diphosphate-alpha-D-glucuronic acid

Easiest explanation: Glucuronide formation takes place in 2 STEPS. The 1st STEP activated coenzyme uridine-5’-diphosphate-alpha-D-glucuronic acid is FORMED from UDP-glucose. The coenzyme ACTS as a donor of glucuronic acid.

Correct choice is (a) Altered PHYSIOLOGY

The explanation is: Altered physiology is the process where due to NUTRITIONAL deficiency an ENZYME content is decreased. THUS decreasing the enzyme content, and decreasing the drug metabolizing time.

Correct ANSWER is (a) True

Best explanation: Esters on hydrolysis YIELD alcohol and CARBOXYLIC acids with the release of a water molecule. The reaction is CATALYSED by esterase.

Right choice is (c) Facilitate electron transfer from NADPH to cytochrome 450

Easy EXPLANATION: Phosphatidylcholine has CHOLINE as a head GROUP. These are major components of the cell membrane. Phosphatidylcholine is a heat stable lipid component which functions to facilitate electron transfer from NADPH to cytochrome 450.

Correct choice is (d) Anything that is not nutrients and enters the body through DIFFERENT routes

The explanation is: All chemical substances that are not nutrients for the body and enter the body through different routes like inhalation, INGESTION, absorption, etc. are KNOWN as XENOBIOTICS. DRUGS are also known as xenobiotics.

Correct OPTION is (a) H2O2 and O2^–

The best I can explain: Most free radicles are organic. Some of the examples of INORGANIC free radicles are H2O2 and O2 and O2-. These oxidative moieties can CAUSE tremendous tissue damage leading to mutations and cancer. The potential TOXICITY of free radicals is more than ELECTROPHILES.

Right answer is (a) Up to 2 months

For explanation I would say: Babies below the AGE of 2 months are CALLED as NEONATES. Their microsomal ENZYMES are not fully developed. Thus takes MUCH longer time to metabolize drugs.

Correct choice is (d) Methacholine

The explanation: Methacholine inhibits the metabolism of ACETYLCHOLINE by competing with it for cholinesterase. It is not an environmental FACTOR. Halogenated pesticides e.g. DDT, polycyclic aromatic hydrocarbon e.g. CIGARETTE smoke, ORGANOPHOSPHATE insecticides, heavy METALS inhibit drug metabolizing of enzymes.

Right choice is (b) Salicylic acids

Easy explanation: Acetylation is an important METABOLIC PATHWAY for drugs containing primary amino GROUPS. Drugs which undergo acetylation reaction are histamine, sulphanilamide, and hydralazine. Acetylation may sometime LEAD to the production of toxic compounds.

Correct ANSWER is (a) 3’-phosphoadenosine-5’-phosphosulfate

Explanation: In the 1st step of sulphation, synthesis of an ACTIVE coenzyme takes place. The coenzyme name is 3’-phosphoadenosine-5’-phosphosulfate. This coenzyme acts as a DONOR of SULFATE to the substrate.

Correct option is (d) Nitrite compounds

Best explanation: The N-containing FUNCTIONAL groups that commonly undergo bioreduction are NITRO, azo, N-oxide compounds. REDUCTION of the nitro group proceeds via FORMATION of nitroso and hydroxylamine intermediates to YIELD amines.

The correct answer is (b) Drug controlling SEEN in twins

Best explanation: Polygenic control has been OBSERVED in twins. In identical twins that are monozygotic twins, there is very little or no difference in drug METABOLISM. It was detected that there was no difference in the metabolism of phenylbutazone, dicoumarol, and antipyrine. Although large variations were detected in dizygotic twins.

The correct answer is (C) Transferase

The explanation is: Phase II reactions INVOLVE the transfer of a SUITABLE moiety such as GLUCURONIC acid SULFATE, glycine, etc. to the phase I reaction. This transfer is mediated by the presence of the enzyme Transferase.

The correct choice is (d) DICHLORO DIPHENYL dichloroethylene

To ELABORATE: In the hydrolytic DEHALOGENATION a molecule of HCL is removed from the substrate. Thus in the case of Dichloro diphenyl trichloroethane when a molecule of HCL is removed we get Dichloro diphenyl dichloroethylene as the product.

The correct answer is (b) NADPH cytochrome P-450 reductase

Explanation: Free radicles are formed via NADPH cytochrome P-450 reductase or other Flavin CONTAINING reductases. QUINONES, arylamines, nitroaryls and carbon tetrachloride are some of the examples of xenobiotics which yields free RADICALS. Endogenous COMPOUNDS such as epinephrine, DOPA can GENERATE free radicals.

Right OPTION is (c) Quinones

To ELABORATE: Quinones, ARYLAMINES, nitroaryls and carbon tetrachloride are some of the EXAMPLES of xenobiotics which yields free radicals. Endogenous compounds such as epinephrine, DOPA can generate free radicals.

Right choice is (d) Their inactivation by CONJUGATION with glutathione

The explanation: The body’s DEFENCE against electrophile is their inactivation by conjugation with glutathione, the most abundant cellular nucleophile wit –SH group. Example of tissue TOXICITY due to ELECTROPHILES is HEPATOTOXICITY of paracetamol metabolites.

The correct answer is (c) Meprobamate

The best explanation: Drugs such as carbamazepine, Meprobamate, CYCLOPHOSPHAMIDE, RIFAMPICIN, etc. STIMULATE their own metabolism. This PHENOMENON is known as auto-induction or self -induction.

Right choice is (d) WHOLE animal kingdom have the COMMON ability to produce D-glucuronic acid

The BEST I can EXPLAIN: The statement d is false since all the mammals have the ability to produce glucuronides. D-glucuronic acid is readily available and can be easily conjugated with other functional groups.

Right choice is (a) Between 1-12 YEAR

To explain: Children and older infant of the age group 1-12 year metabolize several drugs much more rapidly than adults. The rate of metabolism REACHES a MAXIMUM somewhere between 6 MONTHS to 12 years of age. As a result, they require LARGE mg/kg doses in comparison to adults.

The correct choice is (b) Salicylic acid and CH3COOH

The BEST I can explain: Esters like aspirin with large alcoholic and small acidic group when hydrolysed in the PRESENCE of ESTERASE yields US with salicylic acid and CH3COOH as the end product.