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Right option is (d) AMOUNT of solid substrate that GOES into solution under constant time under standard temperature, PH, solvent composition and constant surface area

To explain: 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.

Right OPTION is (a) True

To EXPLAIN: Greater the value faster is the dissolution of the DRUG into solution. Diffusion decreases as the VISCOSITY of the dissolution medium INCREASE.

The CORRECT ANSWER is (c) Disintegration – Deaggregation – Dissolution – Absorption

For explanation: Disintegration of the drug and then Deaggregation and subsequent release of a drug. FOLLOWED by the dissolution of the drug in aqueous FLUIDS at the absorption site and the movement of the dissolved drug through the gastrointestinal membrane into the systemic CIRCULATION.

Right OPTION is (a) Drug solubility

To elaborate: PHARMACEUTICAL factors include factors relating to the physicochemical properties of the drug and DOSAGE. The physicochemical property includes drug solubility, dissolution RATE, particle size, ETC.

The correct ANSWER is (a) Starch

To EXPLAIN: Tween 80 is a solubilizer. Dicalcium PHOSPHATE and tetracycline are inorganic diluents. Starch is ORGANIC diluents. Diluents are added to tablets if the required dosage is inadequate to PRODUCE necessary bulk.

The correct answer is (b) Non-ionized form mostly

To explain I WOULD say: The pH of the STOMACH is 1.5. Ibuprofen being a WEAK acid will be in a UNIONIZED form in the stomach. At pH 7.4 in plasma, it will be in ionized form and in the same format pH 5 in the intestine.

Correct option is (b) Disintegration time

The best I can explain: Physicochemical PROPERTIES of drug substances include drug solubility, dissolution rate, particle size, EFFECTIVE surface area, polymorphism, ETC. Dissolution time comes under Dosage form characteristics and pharmaceutic ingredients.

The correct option is (d) CONVERT DRUG into their salt form

The BEST I can explain: Most drugs are weak acids or weak base3s. THUS, one of the easiest approaches to enhance the solubility and DISSOLUTION of any drug is to convert them into their salt forms.

The correct ANSWER is (a) True

The explanation is: 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).

Right option is (d) Rate of dissolution

To explain I would say: 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.

The correct option is (c) Can pass through the cell membrane

Explanation: A DRUG should not get destroyed by EITHER of acidic or alkaline medium. It must first pass through the biological barrier of cell membrane. Formation of AGGREGATION will decrease its MOLECULAR activity.

Correct choice is (d) Decrease membrane PERMEABILITY

Easiest explanation: Mechanism involved in the increased absorption of the drug is, promotion of WETTING through the increased SURFACE AREA. These also HELP in better membrane contact and enhanced membrane permeability.

The correct answer is (c) Large surface AREA and long residence time

The explanation is: Experiments showed that irrespective of the GI pH and the degree of ionization, most of the acidic and basic drugs are more rapidly absorbed from the intestine. The 1ST reason because of large surface area and second reason DUE to high residence time.

Correct option is (a) PVC

To ELABORATE: PVC is polyvinyl chloride not used as a drug FORMULATION. Hydrophilic diluents such as PEG < PVP, dextrose coat the surface of a hydrophobic MOLECULE to give hydrophilic surface.

The CORRECT choice is (d) Pharmaceutic ingredients

For explanation: Patient-related factors include factors related to anatomy, physiology, and pathologic characteristic of a patient. This includes age, GASTRIC Emptying time, Intestinal TRANSIT time, GASTROINTESTINAL pH, Disease STATES, Blood flow, etc.

The correct ANSWER is (a) The enteral route

For explanation: The enteral route includes delivery peroral. The parenteral route involves ROUTES of administration through skin or under LAYERS of skin. The topical route involves EYES, skins, nose, or other MEMBRANES.

The CORRECT CHOICE is (b) False

To explain: Hydrocarbon CHAINS are oriented inwards to form hydrophobic phase and their polar heads are oriented to form the outer hydrophilic boundaries of the CELL membrane, it surrounds the aqueous environment.

The correct CHOICE is (b) These agents overcome the cohesive strength of the tablets and help in dissolution

For explanation I would say: Disintegrants are the agents which overcome the cohesive strength and break them when they come in contact with the water. Binders are the agents that help in holding the powders TOGETHER to form granules. LUBRICANTS help in the flow of granules and reduce friction between particles. Binders are added when required dosage is INADEQUATE.

Right choice is (a) 1-2

Explanation: The octanol/pH 7.4 buffer partition coefficient value for a DRUG should be in the range of 1-2. This is sufficient for PASSIVE ABSORPTION ACROSS lipodial MEMBRANES.

Correct choice is (c) 1-3

Easiest EXPLANATION: PH range of GUT is from 1-8. PH range of STOMACH is from 1-3 MAKING it the most acidic place in human body. PH range of the intestine (duodenum to the colon) is from 5-8 where most of the DRUGS get absorbed.

Correct answer is (d) Absolute or INTRINSIC solubility

For explanation I WOULD SAY: 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.

Correct answer is (b) Carrier binds reversibly and no covalently with the MOLECULES

The explanation: The carrier-solute COMPLEX can cross the membrane to REACH the other site where the carrier DISCHARGES the solute and RETURNS back to its position. The carriers carry polar charged molecules and are mostly enzymes.

The CORRECT OPTION is (c) PH = pKa + log (Ionized drug concentration/ Unionized drug concentration)

To EXPLAIN: For weak acids, the Henderson-Hasselbach EQUATION is pH = pKa + log (Ionized drug concentration/ Unionized drug concentration). And the % of ionized drug = 10pH-pHKa/1+10PH-pKa * 100.

Correct choice is (c) Rate limiting step

For explanation I would say: The rate at which drug reaches the systemic circulation is DETERMINED by the slowest of the various steps involved in the SEQUENCE. Such a step is known as the rate-limiting. Disintegration time is the time required for the drug to be broken down into smaller particles or AGGREGATES. Dissolution time is the time required for all the drug DISINTEGRATED particle to dissolve in the fluid. Gastric emptying time is the emptying time of the stomach.

The CORRECT CHOICE is (a) HYDROSTATIC pressure

To elaborate: The driving force of pore transport is Hydrostatic pressure and Osmotic pressure across the cell membrane. ELECTROCHEMICAL gradient and concentration gradient is the driving force of PASSIVE diffusion.

Correct choice is (d) POLYVINYL pyrrolidine, Binding agent

The EXPLANATION: Binding agents are used to HOLDING the powders together to form bigger granules. This helps to ensure the tablet remains INTACT. PVP is polyvinyl pyrrolidine used as a binding agent in PHARMACEUTICAL industries.

The CORRECT answer is (d) Drugs that ionize at all pH CONDITIONS

Explanation: Ion-Pair Transport is the mechanism where absorption of drugs like quaternary ammonium compounds, sulphonic acids get absorbed. These drugs can get ionize at all pH conditions. These neutral COMPLEXES have LIPOPHILICITY and AQUEOUS solubility for passive diffusion.

Correct answer is (d) Concentration and ELECTROCHEMICAL gradient both

Explanation: PASSIVE diffusion, the driving FORCES are both concentration gradient and electrochemical gradient. According to Fick’s first law of diffusion, drug MOLECULES always diffuse from the site of higher concentration to the site of lower concentration until equilibrium is attained.

Right choice is (a) True

The EXPLANATION: As SHOWN in experiments, pH absorption curves are less steep and shift to left for BASIC drug and shift to the right for an acidic drug. This led to the hypothesis that a virtual pH ALSO called a microclimate pH exists at the membrane surface.

Right choice is (b) False

Easy explanation: If the pH of EITHER side of the membrane is DIFFERENT, then the compartment whose pH favours greater ionization will have more AMOUNT of drug. And only the IONIZED or the undissociated FRACTION of drug.

Right choice is (c) Use of surfactant and hydrophilic diluents

Explanation: Use of surfactant as a WETTING agent DECREASES the interfacial TENSION and displaces the adsorbed AIR with the solvent and USING hydrophilic diluents coat the surface and render them hydrophilic.

Right answer is (b) Phagocytosis

The BEST explanation: Phagocytosis is a type of ENDOCYTOSIS. Phagocytosis is ALSO called cell eating which includes absorption of solid particulates. Endocytosis is of two types phagocytosis and pinocytosis LATER meaning cell DRINKING.

Right option is (c) Aqueous filled pores

Explanation: Aqueous filled pores of DIAMETER ranging from 4 to 10 Å HELPS to PASS small organic water-soluble molecules and inorganic ions. These pores have polar AMINO acid on the inner SIDE of the pore which helps the water-soluble molecules to easily pass through them.

Correct answer is (c) Macromolecular DRUGS or drugs as oily droplets

For explanation: Macromolecular drugs, Drugs as solid particles and drugs as oily particles are ABSORBED through ENDOCYTOSIS. Passive diffusion helps in the absorption of drugs with MOLECULAR size FRO 100-400 Dalton.

The correct OPTION is (d) Interaction with the excipients and DEGRADATION in an inactive FORM

Easy explanation: A drug for oral use may destabilize either during its shelf life or in the GIT. Thus giving up to two major destabilizing problems that give rise to bioavailability problems are degradation of the drug in inactive form and interaction with one or more different COMPONENTS of the formulation.

The CORRECT choice is (B) Aqueous unstirred diffusion layer

For explanation I would say: The luminal fluid is not in DIRECT CONTACT with the membrane. There stands a BARRIER called as the aqueous unstirred diffusion layer which is interposed between the bulk fluid and the lipoidal membrane.

The correct ANSWER is (b) False

To elaborate: Acidic or WEAK acidic drugs are always present in their ionized form in a basic or neutral environment. In plasma and small intestine with pH 7.4 and 5 respectively, rendering all acidic DRUG be present in their ionized form.

Correct CHOICE is (a) The molecular size of the drug

For explanation I would SAY: The pH-partition hypothesis tells that for drug compounds with molecular weight more than 100, that are transported by passive DIFFUSION across the cell membrane, the process is governed by the CAPABILITY of lipid solubility of UNIONIZED drugs, the dissociation constant of the drug and pH at the absorption site.

Correct choice is (c) DISSOLUTION and permeation through the membrane

The explanation is: 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.

Right CHOICE is (d) 1-2 mg/ml

To ELABORATE: 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.