Category: Drug & Pharmaceutical Biotechnology Objective Questions

Drug Biotechnology Multiple Choice Questions on “Drugs Biotransformation – Phase 1 Reactions -1”.

1. Biotransformation of drugs is defined as the conversion from one physical form to another.
a) True
b) False
Answer: b
Clarification: 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.

2. What are xenobiotics?
a) Another form of antibiotics
b) A form of nutrient
c) Nutrients which kill the gut harmful microbes
d) Anything that is not nutrients and enters the body through different routes
Answer: d
Clarification: 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.

3. The drug biotransformation is a detoxification process.
a) True
b) False
Answer: a
Clarification: 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.

4. What is the active form of salicylic acid?
a) Sialic acid
b) Salic acid
c) Salicylic acid
d) Salicycle acid
Answer: c
Clarification: The salicylic acid is given to a patient on in its inactive form. Through metabolism, this inactive salicylic acid is converted into its active form of Salicylic acid.

5. What is the inactive form of Codeine?
a) Codene
b) Codane
c) Morphine
d) Poppy
Answer: c
Clarification: The codeine is given to a patient on in its inactive form. Through metabolism, this inactive codeine is converted into its active form morphine.

6. What are soft drugs?
a) Drugs given to babies
b) Chemical drugs which are already found in the body
c) Nutrients which kill the gut harmful microbes
d) Anything that is not nutrients and enters the body through different routes
Answer: b
Clarification: 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.

7. Which of the following is the correct decreasing order of drug metabolism?
a) Liver > lungs > kidneys > intestine > placenta > skin > adrenals
b) Liver > lungs > kidneys > intestine > adrenals > placenta > skin
c) Liver > kidneys > lungs > intestine > placenta > adrenals > skin
d) Liver > lungs > intestine > kidneys > placenta > adrenals > skin
Answer: a
Clarification: Liver is the primary site for metabolism. Of most of the drugs. It is because it has most of the enzymes in it that are in large numbers. Metabolism by other organs is very less because they have a very low quantity of enzymes present in them. Thus the order is liver > lungs > kidneys > intestine > placenta > skin > adrenals.

8. The enzymes are divided into two categories, these are _______ and ____________
a) Acidic drug metabolizing and basic drug metabolizing
b) Present in the liver and not present in the liver
c) Microsomal and non-microsomal
d) There is no such division
Answer: c
Clarification: The enzymes are divided into 2 categories namely microsomal and non-microsomal. Microsomal enzymes catalyse the majority of the drug biotransformation reactions. The large variety of microsomal enzymes catalyse a number of oxidative, reductive and hydrolytic reactions.

9. Microsome are selective to ____________
a) Water-soluble drugs
b) Lipid soluble drugs
c) Acidic drugs
d) Basic drugs
Answer: b
Clarification: 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.

10. Where are non-microsomal enzymes present?
a) In the Golgi apparatus
b) Inside lysosomes
c) In the cytoplasm in soluble form
d) In oxysomes
Answer: c
Clarification: 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.

11. Phase 1 reactions are also known as a synthetic reaction.
a) True
b) False
Answer: a
Clarification: Phase I reactions include introducing or removing of –OH, -COOH, -NH2 and –SH. This phase I reactions are also known as functionalization reactions. These transformations are also known as a synthetic reaction.

12. Following are the Phase I reactions except ____________
a) Oxidative reactions
b) Hydrolytic reactions
c) Reductive reactions
d) Sulphide reactions
Answer: d
Clarification: Phase I reactions precedes phase II reactions. These reactions are an oxidative reaction, hydrolytic reactions, and reductive reactions. Phase I reactions include introducing or removing of –OH, -COOH, -NH₂ and –SH. This phase I reactions are also known as functionalization reactions.

13. What are the names of the 3 protein involve in multienzyme mixed-function oxidase system, located in the endoplasmic reticulum?
a) Heme protein, flavoprotein, phosphatidylcholine
b) Heme protein, flavoprotein, retinal protein
c) Heme protein, retinal protein, phosphatidylcholine
d) Retinal protein, flavoprotein, phosphatidylcholine
Answer: a
Clarification: 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.

14. What is the function of Phosphatidylcholine in multienzyme mixed-function oxidase system, located in the endoplasmic reticulum?
a) Oxidising the substrate
b) Reducing the substrate
c) Facilitate electron transfer from NADPH to cytochrome 450
d) Facilitate electron transfer from cytochrome 450 to NADPH
Answer: c
Clarification: 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.

15. What is the function of a flavoprotein, located in the endoplasmic reticulum?
a) Oxidising the substrate
b) Reducing the cytochrome-450 to the ferrous form
c) Facilitate electron transfer from NADPH to cytochrome 450
d) Facilitate electron transfer from cytochrome 450 to NADPH
Answer: b
Clarification: Flavoprotein functions as an electron carrier and catalyses the reduction of cytochrome 450 to ferrous form by transferring an electron from NADPH. Flavoprotein in multienzyme mixed-function oxidase system.

Drug Biotechnology Multiple Choice Questions on “Bioequivalence Studies”.

1. What is bioequivalence?
a) Comparison between 3-year-old drugs to the same new drug
b) Comparison between drugs to another drug
c) Comparison between a drug’s specific characteristics to a defined set of standards
d) Comparison between two or 3 characteristics of a drug to the same characteristics of a different drug
Answer: c
Clarification: Bioequivalence is a relative term which compares drug products with respect to specific characteristics or function to a defined set of standards. There are several types of bioequivalence such as chemical equivalence, pharmaceutic equivalence, bioequivalence, therapeutic equivalence.

2. What is the chemical equivalence?
a) Two or more drug products contain the same labeled chemical substance in the same amount
b) Two or more drug products contain the same labeled chemical substance in different quantity
c) Two or more drug products contain different labeled chemical substance giving the same therapeutic effect
d) Two or more drug products contain the same labeled chemical substance giving a different therapeutic effect
Answer: a
Clarification: Chemical equivalence of drug products is said when the drugs contain the same active ingredient. The amount of the active ingredient must be the same. When two or more drug products contain the same active ingredient giving the same pharmacologic effect is known as therapeutic equivalence.

3. What is pharmaceutic equivalence?
a) Two or more drug products contain the same labeled chemical substance in the same amount
b) Two or more drug products are identical in quality, purity, uniformity, disintegration, dissolution
c) Two or more drug products contain different labeled chemical substance giving the same therapeutic effect
d) Two or more drug products contain the same labeled chemical substance giving a different therapeutic effect
Answer: b
Clarification: Pharmaceutic equivalence implies that two or more drug products when they are identical in strength, purity, content uniformity, and disintegration and dissolution characteristics. Though the excipients may differ. Chemical equivalence of drug products is said when the drugs contain the same active ingredient. The amount of the active ingredient must be the same. When two or more drug products contain the same active ingredient giving the same pharmacologic effect is known as therapeutic equivalence.

4. What is bioequivalence?
a) Drug substance reaches the systemic circulation at the same rate in two or more identical dosage
b) Two or more drug products contain the same labeled chemical substance in different quantity
c) Two or more drug products contain different labeled chemical substance giving the same therapeutic effect
d) Two or more drug products contain the same labeled chemical substance giving a different therapeutic effect
Answer: a
Clarification: Bioequivalence is a relative term which denotes that the drug substance reaches the systemic circulation at the same relative rate or time and to the same extent when given in two or more identical dosage. That is their plasma level concentration-time profile will be identical without significant statistical differences.

5. What is therapeutic equivalence?
a) Two or more drug products contain the same labeled chemical substance in the same amount
b) Two or more drug products contain the same labeled chemical substance in different quantity
c) Two or more drug products contain the same labeled chemical substance giving the same therapeutic effect
d) Two or more drug products contain the same labeled chemical substance giving a different therapeutic effect
Answer: c
Clarification: When two or more drug products contain the same therapeutically active ingredient which elicits the same pharmacological effects and can control the disease to the same extent are known to have therapeutic equivalence. Bioequivalence is a relative term which denotes that the drug substance reaches the systemic circulation at the same relative rate or time and to the same extent when given in two or more identical dosage.

6. On which individuals study of newly invented medicines are not done?
a) Pregnant and elderly
b) Fasting person
c) Healthy person
d) Adult male
Answer: a
Clarification: Drug studies are performed on fasting, young, healthy, adult male volunteers to assure homogeneity in the population. They spare the patients, elderly and pregnant women from such clinical investigations. Homogeneity on the population helps in studying the formulation factors.

7. What should be the disadvantage of cross over study on volunteers?
a) Minimize the intersubject variability in plasma drug levels
b) Minimize the carry-over effect
c) Minimizes variations due to time effect
d) Takes a lot of time to get the result of the study
Answer: d
Clarification: The advantages of randomized, balanced, cross-over study is it minimizes the intersubject variability in plasma drug levels, minimize the carry-over effect, minimizes variations due to time effect, makes it possible to focus on formulation variables. But this method takes a long time because a specific time has to be given for the washout of the previous administration.

8. Two or more drugs contain the same therapeutically active ingredient which elicits same pharmacological effects and can control the disease to the same extent are known to be pharmaceutic equivalent.
a) True
b) False
Answer: b
Clarification: When two or more drug products contain the same therapeutically active ingredient which elicits the same pharmacological effects and can control the disease to the same extent are known to have therapeutic equivalence. Pharmaceutic equivalence implies that two or more drug products when they are identical in strength, purity, content uniformity, and disintegration and dissolution characteristics.

9. If the bioavailability of test formulation is 80-120% of the reference standard, it is considered to be bioequivalent.
a) True
b) False
Answer: a
Clarification: A significant difference of 10% in the extent of absorption between the two formulations is clinically insignificant. Thus, a rule is that if the relative bioavailability of the test formulation is in the range 80-120% 0f reference standard, it is considered to be bioequivalent.

10. Bioequivalence is a relative term which denotes that the drug substance reaches the systemic circulation at the same relative rate or time.
a) True
b) False
Answer: a
Clarification: Bioequivalence is a relative term which denotes that the drug substance reaches the systemic circulation at the same relative rate or time and to the same extent when given in two or more identical dosage. That is their plasma level concentration-time profile will be identical without significant statistical differences. When statistically significant differences are observed in the bioavailability of two or more drug products, bioequivalence is shown.

Drug Biotechnology Multiple Choice Questions on “Controlled Release Medication – Clinical Trials – 1”.

1. Which of the following are not correct on the basis of clinical trials?
a) Biomedical research studies
b) Behavioral research studies
c) Studies on human subjects
d) Study based only on animals
Answer: d
Clarification: Clinical trials are biomedical or behavioral research studies on human subjects that are designed to answer specific questions about biomedical or behavioral interventions such as novel vaccines, drugs, treatments, devices or new ways of using known interventions, generating safety and efficacy data. These trials are to test the safety and efficacy of a newly invented drug.

2. What are the different types of clinical trials according to the U.S. National Institutes of Health?
a) 6
b) 5
c) 4
d) 3
Answer: a
Clarification: The U.S institutes of health organize trials into 6 different types and these are prevention trial, screening trial, diagnostic trial, treatment trial and quality of life trials. One way of classifying clinical trials is, by the way, the researchers behave that is an observational study and other is interventional study.

3. What do you mean by a randomized design?
a) The subjects do not know which study treatment they receive
b) Patients injected with placebo and active doses
c) Randomly assigning subjects either for placebo or active dose
d) Signed document of the recruited patient for the clinical trial procedures
Answer: c
Clarification: Randomized design is when each study subject is randomly assigned to receive either the study treatment or a placebo. The subjects involved in the study do not know which study treatment they receive. If the study is double-blind, the researchers also do not know which treatment is being given to any given subject.

4. What is meant by a blind subject?
a) The subjects do not know which study treatment they receive
b) Patients injected with placebo and active doses
c) Fake treatment
d) Signed document of the recruited patient for the clinical trial procedures
Answer: a
Clarification: The subjects involved in the study do not know which study treatment they receive. If the study is double-blind, the researchers also do not know which treatment is being given to any given subject. In this kind of study the subjects or the patients will not be knowing which study treatment they receive.

5. Which one of the following describes “double dummy”?
a) The subjects do not know which study treatment they receive
b) Patients injected with placebo and active doses
c) Fake treatment
d) Signed document of the recruited patient for the clinical trial procedures
Answer: b
Clarification: A form of double-blind study called a “double-dummy” design allows additional insurance against bias or placebo effect. In this kind of study, all patients are given both placebo and active doses in alternating periods of time during the study. The use of a placebo (fake treatment) allows the researchers to isolate the effect of the study treatment.

6. What is placebo?
a) The subjects do not know which study treatment they receive
b) Patients injected with placebo and active doses
c) Fake treatment
d) Signed document of the recruited patient for the clinical trial procedures
Answer: c
Clarification: The use of a placebo (fake treatment) allows the researchers to isolate the effect of the study treatment. It allows the researchers to see the effect on the patients or the healthy individual when they don’t get the drug rather they get a fake treatment. In this kind of study, all patients are given both placebo and active doses in alternating periods of time during the study.

7. What is informed consent in a clinical trial?
a) The subjects do not know which study treatment they receive
b) Patients injected with placebo and active doses
c) Fake treatment
d) Signed document of the recruited patient for the clinical trial procedures
Answer: d
Clarification: An essential component of initiating a clinical trial is to recruit study subjects following procedures using a signed document called “informed consent.” Fake treatment or placebo allows the researchers to isolate the effect of the study treatment. Patient injected with active dose and placebo is also known as a double dummy.

8. Which one of the following is the last step of a clinical trial process?
a) Investigator selection
b) Patient recruitment
c) Statistical Analysis
d) Data filed and registration
Answer: d
Clarification: The last step of the clinical trial is when the data are filed and registration from the FDA is obtained and the product is ready to be marketed. FDA approves the New Drug Application. Now the drug appears in the market and post-marketing studies, inspection starts.

9. Which one of the following will perfectly fit on the marked place?

a) Investigator selection
b) Patient recruitment
c) Statistical Analysis
d) Data filed and registration
Answer: c
Clarification: This step involves checking the ratios, checking the number of patients who are showing which symptom, who are not so that they can have a proper count of how many patients may get benefited from the dosage. The statistical analysis is an important part which also involves dosage, age, patient details, study details etc.

10. Which one of the following will perfectly fit on the marked place?

a) Investigator selection
b) Patient recruitment
c) Statistical Analysis
d) Data filed and registration
Answer: b
Clarification: After FDA has approved the IND the manufacturer company has to choose groups of patients and healthy people with their informed consent to start the procedure of the phase I trial. This the patient recruitment phase. Once the healthy individual for phase I trial are selected and the phase I trial is successful they have to again recruit for phase II trial.

11. Which one of the following will perfectly fit on the marked place?

a) Investigator selection
b) Patient recruitment
c) Statistical Analysis
d) Data filed and registration
Answer: a
Clarification: After the laboratory studies are over the company submits IND and thus FDA if approves the IND will start the clinical trial phases. In this time the manufacturing company have to choose the Investigator who will investigate and keep a report of the whole process of phase I, II, III, IV.

12. How many people will be selected for phase I trial?
a) The whole market will be under surveillance
b) 300-3000 people
c) 20-300 people
d) 20-50 people
Answer: d
Clarification: Phase I trials are the first stage of testing in human subjects. Normally, a small group of 20-50 healthy volunteers will be selected. This phase includes trials designed to assess the safety (pharmacovigilance), tolerability, pharmacokinetics, and pharmacodynamics of a drug. Phase 2 trial will be done on 20-300 people. Phase 3 trial will be done on 300-3000 people.

13. How many people will be selected for phase II trial?
a) The whole market will be under surveillance
b) 300-3000 people
c) 20-300 people
d) 20-50 people
Answer: c
Clarification: Once the initial safety of the study drug has been confirmed in Phase I trials, Phase II trials are performed on larger groups 20-300 and are designed to assess how well the drug works, as well as to continue Phase I safety assessments in a larger group of volunteers and patients. Phase 1 trial will be done on 20-50 people. Phase 3 trial will be done on 300-3000 people. Phase 4 trial is post-marketing surveillance.

14. How many people will be selected for phase III trial?
a) The whole market will be under surveillance
b) 300-3000 people
c) 20-300 people
d) 20-50 people
Answer: b
Clarification: Phase III studies are controlled tests on large patient groups 300–3,000 or more depending upon the disease and are aimed at being assessment of how effective the drug is, in comparison with current treatment method. Phase 1 trial will be done on 20-50 people. Phase 2 trial will be done on 20-300 people. Phase 4 trial is post-marketing surveillance.

15. Which one of the following will be checked under phase IV surveillance?
a) The whole market will be under surveillance
b) 300-3000 people
c) 20-300 people
d) 20-50 people
Answer: a
Clarification: Phase IV trial is also known as Post Marketing Surveillance Trial. Phase IV trials involve safety surveillance (pharmacovigilance) and ongoing technical support of a drug after it receives permission to be sold. Phase 1 trial will be done on 20-50 people. Phase 2 trial will be done on 20-300 people. Phase 3 trial will be done on 300-3000 people.

Pharmaceutical Biotechnology Questions and Answers for Experienced people on “Immunological Preparations – Classification of Vaccines”.

1. Who developed the first vaccine?
a) Pasteur
b) Salk
c) Jenner
d) Landsteiner

Answer: c
Clarification: Edward Jenner introduced small pox which was the first successful vaccine for smallpox in the year 1796. He injected cowpox virus into a boy and then he found out he has become immune to smallpox. That is how the smallpox vaccine was invented.

2. What causes smallpox?
a) Bacteria
b) Virus
c) Fungi
d) Protozoa

Answer: b
Clarification: Small pox was an infectious disease. It was caused by one or two variants of Variola major and Variola minor. It was a major disease in earlier days. But due to the invention of Edward Jenner and other recent developments, it was completely wiped out from the country.

3. Vaccines are used in all the forms, except _________
a) Live-attenuated vaccines
b) Inactivated vaccines
c) Subunit, recombinant, polysaccharide, and conjugate vaccines
d) Attenuated, inactivated, portions of protein, polysaccharides

Answer: d
Clarification: There are 3 main types of vaccine: live-attenuated vaccines; inactivated vaccines; and subunit, recombinant, polysaccharide, and conjugate vaccines. The vaccine is something which will activate the immune system up to the memory level. So that memory cells are produced in the body to protect from any further infection.

4. Which vaccine among these is used in its inactivated form?
a) Influenza
b) Measles
c) Mumps
d) Chickenpox

Answer: a
Clarification: Influenza vaccine is inactivated virus; measles, mumps, and chicken pox vaccines are live- attenuated viruses. Inactivated viruses are inactive to cause any diseases. They have their cell membrane proteins intact.

5. What is the key information required to develop a vaccine?
a) Molecular pathogenicity of the disease
b) Molecular pathogenicity of the disease-causing organism
c) Unique immunologic response from the host
d) Molecular pathogenicity of the disease and the disease-causing organism

Answer: d
Clarification: Key information required to develop a vaccine are: molecular pathogenicity of the disease or disease-causing organism (50%) and unique immunologic response from host (50%). The unique immunologic response from the host will decide the dosage form for the particular patient.

6. Who sets the rules for clinical trials?
a) NHS- National Health Service
b) NIH- National Institute of Health
c) NDA- New Drug Administration
d) FDA- Food and Drug Administration

Answer: d
Clarification: Food and Drug Administration (FDA) sets rules for the three phases of clinical trials to ensure the safety of the volunteers. Every researcher or manufacturer has to get a drug approved by the FDA. FDA sets rules for the manufacturing guidelines.

7. The BCG vaccine was developed by ___________ and ____________
a) Albert Calmette and Camille Guérin
b) Marry Currie and Perry Currie
c) Albert Einstein
d) Robert Hook

Answer: a
Clarification: The BCG vaccine was developed by French bacteriologists Albert Calmette and Camille Guérin. They named the vaccine or the product Bacillus Calmette-Guérin, or BCG.

8. A recombinant engineered vaccine is “direct manipulation of genes of weakened or killed pathogen for stimulating antibody production or cellular immunity against the pathogen but is incapable of causing severe infection”.
a) True
b) False

Answer: a
Clarification: A manipulation of genes of a weakened or killed pathogen, such as bacteria or virus that upon administration to a human body or any other animal will stimulate antibody production or cellular immunity against the pathogen. But this will be incapable of causing any severe disease or infection are known as recombinant engineered vaccines.

9. Recombinant engineered vaccines are being extensively explored to eradicate the following factors, except _________
a) Infectious diseases
b) Cancers
c) Allergies and cancers
d) Mental illness

Answer: d
Clarification: Recombinant engineered vaccines are being extensively explored, especially to eradicate infectious diseases, allergies, and cancers. Recombinant vaccines are manufactured by the recombinant DNA process. The vaccine will be able to provide immunogenicity to more diseases.

10. __________ demonstrated a plasmid-induced immune response using mice by inoculating with a plasmid expressing human growth hormone which elicited antibodies instead of faltering growth.
a) Stephen Johnston
b) Karry Mullis
c) Robert Hook
d) Alexander Fleming

Answer: a
Clarification: Stephen Johnston’s group saw that when mice are inoculated with plasmid DNA encoding human growth hormone, the mice is able to produce antibodies against this hormone. It was the first demonstration of a plasmid-induced immune response was when mice inoculated with a plasmid expressing human growth hormone elicited antibodies instead of faltering growth.

Pharmaceutical Biotechnology for Experienced people,

 

Tricky Drug Biotechnology Questions and Answers on “Physicochemical Factors Affecting Drug Absorption”.

1. Which one of the following is a critical rate-limiting step of drug absorption?
a) Rate of drug disintegration
b) Size of the drug
c) Size of the porous particle
d) Rate of dissolution
Answer: d
Clarification: For orally administered drug, the two critically slower rate determining step is the rate of dissolution and the rate of drug permeation. Dissolution is the rate determining stem for poorly aqueous soluble drugs and hydrophobic drugs.

2. Which sentence will define the Dissolution rate?
a) Amount of solid substrate that goes into solution under constant time
b) Amount of solid substrate that goes into solution under constant time under standard temperature
c) Amount of solid substrate that goes into solution under constant time under standard temperature, pH, and pressure
d) Amount of solid substrate that goes into solution under constant time under standard temperature, pH, solvent composition and constant surface area
Answer: d
Clarification: Dissolution rate is defined as the amount of solid substrate that goes into solution under constant time under standard temperature, pH, solvent composition and constant surface area. It is a dynamic process. Drugs having poor aqueous solubility have less dissolution rate.

3. What should be the ideal solubility rate of an orally administered drug in the pH range of 2 to 8?
a) 3-4mg/ml
b) 4-6 mg/ml
c) 7-8 mg/ml
d) 1-2 mg/ml
Answer: d
Clarification: The solubility of any orally administered drug should be between 1-2 mg/ml in the range of pH 2-8. The solubility becomes a great matter of concern if it is less than that. And if more than that the dosage must be carefully calculated.

4. Which one of these is not a theory of Drug dissolution?
a) Diffusion layer model
b) Fick’s law of diffusion
c) Penetration or surface renewal theory
d) Interfacial barrier model
Answer: b
Clarification: Fick’s law of diffusion states that drug molecules diffuse from higher concentration to lower concentration until equilibrium is reached. Theories of drug dissolution are Diffusion layer model or Fil theory, Danckwert’s model or Penetration or surface renewal theory, Interfacial barrier model or Double barrier theory.

5. Which theory takes into account that a thin film is created by the solution of the solid at the solid-liquid interface?
a) Interfacial barrier model
b) Diffusion layer model
c) Penetration or surface renewal theory
d) Danckwert’s model
Answer: b
Clarification: Diffusion layer model states that solution of a solid form a thin film or layer at the solid-liquid interface which is called as the stagnant film or diffusion layer which gets saturated with the drug. This step is rapid.

6. In the equation G=Ki (Cs-Cb), what does G stands for______________
a) Dissolution rate per unit area
b) Effective interfacial transport constant
c) Concentration of the solute
d) Concentration of the impurity
Answer: a
Clarification: According to the interfacial barrier model, an intermediate concentration exists at the interface which is a result of the solvation mechanism and is a function of solubility. Here in the equation G stands for dissolution rate per unit area, Ki stands for effective interfacial transport constant.

7. Which model does not approve the existence of the stagnant layer in the solid-liquid interface?
a) Interfacial barrier model
b) Diffusion layer model
c) Penetration or surface renewal theory
d) Danckwert’s model
Answer: d
Clarification: Danckwert did not approve the existence of the stagnant layer and suggested that turbulence in the dissolution medium exists at the solid/liquid interface. Due to which the agitated fluid consists of a macroscopic mass of eddies or packets reach the solid-liquid interface due to the eddy currents, absorb the solute by diffusion and carry it to the bulk of the solution.

8. What does the interfacial barrier model states?
a) An intermediate concentration exists at the interface
b) Turbulence in the dissolution medium exists at the solid/liquid interface
c) Formation a thin film or layer at the solid-liquid interface
d) Solutes passes easily through the interfaces
Answer: a
Clarification: An intermediate layer exist at the interface of the solid and liquid layers. This intermediate layer holds and intermediate concentration at the interface which results is solvation mechanism. The theory does not talk about any turbulence, or presence of solutes.

9. In the equation, Wo1/3-W1/3=Kt, K stands for ____________
a) The original mass of the drug
b) Mass of the drug remaining after time t
c) Dissolution constant
d) Concentration of solute
Answer: c
Clarification: To calculate the particle size decrease and change in the surface area of the dissolution Hixson and Crowell’s cubit root law of dissolution is followed, Wo1/3-W1/3=Kt, where, Wo stands for original mass of the drug, W stands for the mass of the drug remaining after time t, K stands for dissolution constant.

10. Which are the two rate-determining step of drug absorption when given orally?
a) Disintegration and deaggregation
b) Disintegration and Dissolution
c) Dissolution and permeation through the membrane
d) Permeation through the membrane and Disintegration
Answer: c
Clarification: The two critical slower rate-determining processes in the absorption of orally administered drugs are the rate of dissolution and rate of the solute or the drug permeation through the cell membrane or biomembrane.

11. The maximum amount of solute dissolved in a given solvent under standard conditions of temperature, pressure, and pH is known as __________
a) Dissolution rate
b) Intrinsic dissolution
c) Rate limiting step
d) Absolute or intrinsic solubility
Answer: d
Clarification: Absolute or intrinsic solubility is defined as the maximum amount of solute dissolved in a given solvent under standard conditions of temperature, pressure, and pH. It is a static property. Dissolution rate is the amount of a solid substance that dissolves into solution under given conditions.

12. In the equation, V dC/dt = dm/dt = A(Cs-Cb).√ γ D, what does γ stands for?
a) Mass of the solid dissolved
b) Rate of surface renewal
c) Concentration of solute
d) Concentration of the drug
Answer: b
Clarification: The Danckwert’s model is expressed by the equation, V dC/dt = dm/dt = A (Cs-Cb).√ γ D, where γ is the rate of surface renewal, m is the mass of solid dissolved. Cs concentration of the solute.

13. Each face of the crystal has a different interfacial barrier.
a) True
b) False
Answer: a
Clarification: The statement is true. According to the interfacial barrier model, each face of a crystal has a different interfacial barrier. This concept is given by G=Ki (Cs-Cb).

To practice Tricky questions and answers on all areas of Drug Biotechnology,

Drug Biotechnology Questions and Answers for Experienced people on “Drugs Biotransformation – Phase 1 Reactions – 2”.

1. Which one is the rate-limiting step in the oxidation of xenobiotics?
a) Binding of the substrate to Fe³⁺
b) Electron transfer from NADPH to the above complex
c) The enzyme-substrate complex combines with a molecule of oxygen forming a ternary complex
d) Ternary complex gains an electron from the NADPH
Answer: b
Clarification: The rate-limiting step is the transfer of an electron from NADPH to the complex of substrate and cytochrome 450. The gaining of an electron by cytochrome 450 reduces the Fe³⁺ to Fe²⁺. This step is considered the rate-limiting step of the oxidation of xenobiotics.

2. What provides the atom of oxygen for the making of water?
a) From the cytochrome 450
b) From the environment
c) From the activated oxygen P-450 substrate complex
d) From cytochrome reductase
Answer: c
Clarification: 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.

3. What is the major end product of oxidation of aromatic carbon atoms?
a) Arenols
b) Catechol
c) Glutathione
d) Arene oxide
Answer: a
Clarification: 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.

4. Which one of the following is reactive and a known carcinogenic?
a) Cytochrome P-450
b) Catechol
c) Glutathione
d) Arene oxide
Answer: d
Clarification: The oxidation of aromatic carbon atoms proceeds via formation of a reactive intermediate arene oxide. This arene oxide is a known carcinogenic or even cytotoxic in some instances.

5. Which of the following is not a common N containing functional groups which undergo reduction reactions?
a) Nitro compounds
b) Azo compounds
c) N-oxide compounds
d) Nitrite compounds
Answer: d
Clarification: 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.

6. Esters on hydrolysis yields alcohol and carboxylic acid.
a) True
b) False
Answer: a
Clarification: Esters on hydrolysis yield alcohol and carboxylic acids with the release of a water molecule. The reaction is catalysed by esterase.

7. Which enzymes catalyses the hydrolysis of amides?
a) Esterase
b) Amydases
c) Amidases
d) Aminodases
Answer: c
Clarification: The reaction of hydrolysis of amides is catalysed by amidases. The reaction involves C-N bond cleavage thus yielding carboxylic acid and amine. Amides are hydrolysed slowly in comparison to esters.

8. What is the end product of hydrolysis of Lidocaine?
a) 2, 6-Xylidine, N, N-Dimethylglycine
b) 2, 5- Xylidine, Dimethylglycine
c) Xylidine, glycine
d) 1, 6-Xylidine
Answer: a
Clarification: 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.

9. What is the end product of hydrolytic dehalogenation of DDT?
a) Dichloro diphenyl ethylene
b) 1- chloro diphenyl dichloroethylene
c) Trichloro triphenyl trichloroethylene
d) Dichloro diphenyl dichloroethylene
Answer: d
Clarification: 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.

10. What does the hydrolysis of Aspirin yield us with?
a) Salicylic acid only
b) Salicylic acid and CH₃COOH
c) CH₃COOH
d) Succinic acid
Answer: b
Clarification: 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.

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