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Right answer is (d) Coarse drug

Best explanation: Solid solutions are prepared by fusion method where a mixture of solute and solvent are melted together followed by RAPID solidification. Such systems are prepared by fusion and are called as MELTS e.g. griseofulvin-succinic acid. A solid solution is a BINARY system with solid solute DISPERSED in a solid solvent. Eutectic mixtures are physically blended mixture of two crystalline COMPOUNDS.

Correct option is (c) Inorganic clays LIKE bentonite

Explanation: In the process of selective adsorption on insoluble carriers a HIGHLY active adsorbent as the inorganic clays like bentonite can ENHANCE the dissolution rate of poorly aqueous soluble DRUGS such as indomethacin, it maintains the concentration GRADIENT at its maximum.

The correct option is (b) False

To explain I would say: 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.

Correct CHOICE is (a) (dXu/dt)max

The BEST explanation: (dXu/dt)max is the maximum urinary excretion rate. This is obtained from the PEAK of the rate of excretion versus midpoint time of urine collection period. It is analogous to Cmax from plasma level studies since the rate of APPEARANCE of drug in the urine is proportional to its concentration in circulation. Its value increases as the rate of absorption increases. (tu)max is the time for maximum excretion rate, its value decreases as the absorption rate increases. Xu is the CUMULATIVE amount of drug excreted in the urine.

Correct choice is (d) TWO COMPARTMENT model with ELIMINATION from both the compartments

Easy EXPLANATION: Depending upon the compartment from which the drug is eliminated, the two compartment model can be categorized into 3 types, these are, two compartment model with elimination from the CENTRAL compartment, peripheral compartment, and both the compartments.

Right answer is (a) 1-10 micron

The best explanation: MICRONIZATION is a process where the size of the solid drug particles is reduced to 1-10 microns by SPRAY DRYING or by using air attrition methods. Drugs such as GRISEOFULVIN and several steroidal and sulfa drugs are there whose bioavailability is increased by micronization.

Correct choice is (c) Two or more drug products contain the same labeled chemical substance giving the same therapeutic effect

To explain I would say: 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.

The correct answer is (d) Cmax

Easy explanation: (dXu/dt)max is the maximum urinary excretion rate. It is analogous to Cmax from plasma level STUDIES since the rate of appearance of DRUG in the urine is proportional to its concentration in CIRCULATION. Its value increases as the rate of absorption increases. (TU)max is the time for maximum excretion rate, its value decreases as the absorption rate increases. Xu is the cumulative amount of drug excreted in the urine.

The correct answer is (c) Mixed order kinetics

The explanation: The PLOT is of Michaelis-Menten equation –dC/dt = Vmax C/Km+C, Initially the RATE increases linearly with concentration thus SHOWING FIRST order kinetics. It becomes mixed order at intermediate DOSES and then reaches maximum Vmax. Beyond this, it proceeds at a constant rate.

The correct option is (b) Cyclodextrin

The explanation: Beta and GAMMA Cyclodextrin and other DERIVATIVES have the ABILITY to form molecular inclusion COMPLEXES with hydrophobic drugs having poor aqueous solubility. These Cyclodextrin molecules have a hydrophobic cavity which can accommodate the lipophilic drugs as a guest. The outside of which is hydrophilic.

Correct option is (b) In SITU salt formation

Explanation: Alteration of pH of the drug microenvironment is done in two ways. One of that is in-situ salt formation, and other is the addition of BUFFERS to the formulation e.g. buffered aspirin tablets. We cannot DEPEND on tissue pH since it changes PERSON to person.

The correct answer is (b) Organic solvent

For explanation: INSOLVENT deposition method, poorly aqueous SOLUBLE DRUGS are dissolved in an organic solvent such as alcohol and deposited on an inert, HYDROPHILIC, solid matrix such as that of STARCH or microcrystalline cellulose by evaporation of the solvent.

Right answer is (d) Partition coefficient approach

The explanation is: There are THREE approaches in overcoming the BIOAVAILABILITY problems these are the pharmaceutic approach, pharmacokinetic approach, and biologic approach. The pharmaceutic approach involves MODIFICATION of formulation, manufacturing processes. The pharmacokinetic approach is in which the pharmacokinetics of the DRUG is altered by modifying its chemical structure. The biologic approach is where the route of administration can be changed.

Correct answer is (d) Control the quantity of the drug to be administered

Easy explanation: More than the quantity, bioavailability studies are more used to study the quality of a drug product during the early stages of MARKETING so that the influence of processing factors, storage, and stability on drug ABSORPTION can be DETERMINED. Other objectives are the development of suitable dosage form, determination of the influence of EXCIPIENTS, patient-related factors, etc. and development of NEW formulations of the existing drugs.

Correct option is (a) True

Easy explanation: Urinary excretion studies help in assessing bioavailability is based on the principle that urinary excretion of unchanged drug is DIRECTLY PROPORTIONAL to the plasma concentration of a drug. If a drug is excreted at LEAST 10 to 20% in the urine, bioavailability can be DETERMINED.

Right answer is (d) Plasma drug concentration IMMEDIATELY after i.v. INJECTION

For EXPLANATION I would say: In the equation log C = log CO – KEt/2.303, C is the drug concentration in plasma, Co is the plasma drug concentration immediately after i.v. injection, KE is the overall elimination rate constant, t is time.

The correct CHOICE is (a) True

The explanation: SALTS improve solubility and dissolution property of the drug in comparison to the original characteristic. Alkali metal salts of acidic drugs and strong acidic salt of the basic drug are more WATER soluble than the parent drug. For EXAMPLE penicillin and atropine RESPECTIVELY.

The correct answer is (a) The central compartment in a TWO compartment MODEL

To EXPLAIN: In the graph, the MARKED curve is showing the drug concentration of the central compartment. Initially, the drug concentration of the central compartment in a two compartment model declines rapidly because of the rapid distribution of the drug from the central compartment to the peripheral compartment. This phase is known as the DISTRIBUTIVE phase.

Correct option is (C) Unidirectional INPUT and output

Explanation: The term OPEN indicates that the input and the output are unidirectional and the DRUG can be eliminated from the body. One compartment open model does not assume that drug concentration in plasma is equal to that in other body tissue.

The correct option is (C) Micronized drug

The BEST explanation: Solid solutions are prepared by fusion method where a mixture of solute and solvent are melted TOGETHER followed by rapid solidification. Such systems are prepared by fusion and are called as MELTS e.g. griseofulvin-succinic acid. Solid SOLUTION is binary system with solid solute dispersed in solid solvent. Eutectic mixtures are physically blended mixture of two crystalline compound.

The correct choice is (a) True

For explanation: A drug with poor bioavailability means the drug can also have poor aqueous solubility, slow dissolution rate in plasma or other BIOLOGICAL fluids. The drug can also have poor stability of the dissolved drug at the patient’s body pH, inadequate PARTITION coefficient, and EXTENSIVE presystemic METABOLISM.

Correct choice is (a) PREGNANT and elderly

The explanation: 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.

Correct OPTION is (b) Rate of elimination by kidney/PLASMA drug concentration

The EXPLANATION: The HEPATIC clearance is given by the equation Rate of elimination by kidney/plasma drug concentration. The RENAL clearance is given by the equation Rate of elimination by liver/ plasma drug concentration.

The correct ANSWER is (b) False

The explanation is: Poor stability of the DRUG at physiological pH causes the difference in its disintegration, dissolution rate thus DECREASING the bioavailability. The drug can also have poor stability of the DISSOLVED drug at the patient’s body pH, inadequate partition coefficient, and extensive presystemic metabolism.

Right OPTION is (d) Saturation of BINDING sites on plasma proteins

To elaborate: Nonlinearity in DRUG absorption can ARISE from 3 important sources these are when absorption is solubility or dissolution rate-limited, when absorption involves carrier-mediated transport systems and when presystemic gut wall or hepatic metabolism attains saturation. Nonlinearity in drug distribution occurs when saturation of binding sites on plasma proteins or saturation of tissue binding sites.

Right OPTION is (a) Solid solution

To elaborate: Solid solutions are prepared by FUSION method where a mixture of solute and solvent are melted together followed by rapid SOLIDIFICATION. Such SYSTEMS are prepared by fusion and are called as melts e.g. griseofulvin-succinic acid. Solid solution is binary SYSTEM with solid solute dispersed in solid solvent. Eutectic mixtures are physically blended mixture of two crystalline compound.

Correct OPTION is (a) True

Easy explanation: 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.

The correct option is (a) True

Best explanation: Therapeutic RESPONSE is based upon the clinical responses to a drug FORMULATION GIVEN to patients suffering from the disease for which the drug should be used. A drawback of the method is the quantification of observed response is not proper to allow for ASSESSMENT of relative bioavailability between dosage FORMS of the same drug.

Right answer is (d) Takes a lot of time to get the result of the study

Best explanation: 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.

Right option is (a) Drug substance reaches the systemic circulation at the same rate in two or more identical dosage

To explain I WOULD say: 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.

Correct CHOICE is (b) Enhancing the dissolution rate by PROMOTING wetting

To explain I would say: Surfactants enhance the dissolution rate by promoting wetting and penetration of dissolution fluid into the solid DRUG particles. These surfactants are used in a CONCENTRATION below the critical micellar concentration since above CMC the trapped drug in the micelle structure fails to partition in the dissolution fluid.

The CORRECT option is (d) Steady state level

Easiest explanation: Cmax is the peak plasma concentration which shows WHETHER the drug is being absorbed systemically so that it can be able to provide a therapeutic response. Tmax is the peak time which will give the indication of the RATE of ABSORPTION. The AREA under the plasma level-time curve gives the measure of the quantity of absorption of the drug that reaches the systemic circulation.

Correct answer is (c) BIOAVAILABLE dose/Administered dose

Explanation: The amount of DRUG that REACHES the systemic circulation is known as systemic bioavailability. The bioavailable FRACTION F REFERS to the fraction of administered dose that enters the systemic circulation after drug administration. The equation is F = Bioavailable dose/Administered dose.

Right answer is (a) Acute pharmacologic RESPONSE

Explanation: Pharmacodynamic methods are a direct measurement of the drug effect on PHYSIOLOGICAL processes as a FUNCTION of time. The methods are acute pharmacologic response and therapeutic response. Pharmacokinetics method is indirect methods and these are Plasma level time STUDIES and Urinary excretion studies.

Right option is (a) –dC/dt = Vmax C/Km+C

To explain: The kinetics of capacity-limited or saturation process is DESCRIBED by Michaelis-Menten equation, the equation is –dC/dt = Vmax C/Km+C, where –dC/dt = rate of decline of DRUG concentration with TIME, Vmax is the THEORETICAL maximum rate of the process and Km is Michaelis constant.

Right option is (a) True

Easiest explanation: Some of the pharmacokinetic FACTORS such as fraction bioavailable, ELIMINATION half-life or TOTAL systemic clearance at different DOSES of drug normally remains constant. If any changes occur in these constants, this indicates nonlinearity.

The correct answer is (a) a

Easy explanation: At Cmax, where the plasma concentration rate is at the maximum that is ABSORPTION rate is at the maximum at that POINT for that short INTERVAL of TIME the ELIMINATION rate is equal to the absorption rate.

The correct ANSWER is (d) Time take for half of the amount of drug to get completely eliminated from the body as well as PLASMA

The EXPLANATION is: Also known as the BIOLOGICAL half-life. It is defined as the time taken for half amount of drug in the body and plasma concentration to decline by one-half of its initial value. It is expressed in hours or minutes. T-half = 0.693/KE.

Right choice is (a) Highly water-soluble compound

To explain I would say: There are three different ways of SOLID solutions these are the use of the solid solution, use of eutectic mixtures, and the use of solid dispersions. In all these cases the solute or the DRUG is most of the times not soluble in water acts as a GUEST and the solvent used is highly water-soluble compound or polymer ACTING as a host or carrier.

Correct option is (b) False

For explanation I would say: Physicochemical property of most of the drugs that have the greatest influence on their ABSORPTION characteristics from the gastrointestinal tract is dissolution rate. To assess the therapeutic efficacy of slow dissolving drugs is in VIVO determination of bioavailability. It is DONE WHENEVER a new formulation is to be INTRODUCED in the market.

The CORRECT answer is (B) The peripheral compartment in a two compartment model

The BEST explanation: In the GRAPH, the marked curve is showing the drug concentration of the peripheral compartment of a two compartment model. The drug concentration in the peripheral compartment first increases and reaches the MAXIMUM. Then due to loss of drug starts due to elimination. This is the post distributive or elimination phase.

Correct answer is (b) Two or more drug products are identical in quality, purity, uniformity, DISINTEGRATION, dissolution

The best explanation: 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.

Right option is (d) Serum drug level

The explanation: When bioavailability MEASUREMENT using pharmacokinetic processes are difficult, INACCURATE, non-reproducible, acute PHARMACOLOGICAL effect such as a change in ECG, EEG, pupil DIAMETER, etc. is related to the time course of a given drug. Bioavailability can then be calculated by construction the pharmacologic effect-time CURVE as well as dose-response graphs.

Correct answer is (a) Michaelis-Menten plot

To explain: The plot is of Michaelis-Menten EQUATION –dC/dt = Vmax C/Km+C, Initially the rate increases linearly with concentration thus SHOWING first order kinetics. It becomes MIXED order at HIGHER concentration and then reaches maximum Vmax. Beyond this, it proceeds at a constant rate.