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UPSC Drug Inspector practice questions

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Question 1Pharmaceutical Chemistry

Which pharmacopoeial technique is used to determine the water content of a drug substance by measuring the volume of Karl Fischer reagent consumed?

  1. Thermogravimetry
  2. Loss on drying
  3. Karl Fischer titration Correct answer.
  4. Azeotropic distillation

Explanation

Karl Fischer titration is a specific and stoichiometric method in which iodine, sulphur dioxide and water react in the presence of a base, and the endpoint reflects the amount of water present. It is the reference method for moisture determination in hygroscopic and thermally unstable drugs.

Question 2Pharmaceutical Chemistry

In the assay of a weakly basic amine drug, the titration is best performed in which solvent so that the endpoint can be detected potentiometrically?

  1. Glacial acetic acid Correct answer.
  2. Ethanol
  3. Chloroform
  4. Water

Explanation

In non-aqueous titrimetry, glacial acetic acid is a protogenic solvent that enhances the basicity of weak bases so they can be titrated with perchloric acid. The titration is monitored potentiometrically with a glass indicator electrode because ordinary indicators may fail in this medium.

Question 3Pharmaceutical Chemistry

Which official test distinguishes a reducing sugar from a non-reducing sugar in a pharmaceutical excipient like sucrose?

  1. Ninhydrin test
  2. Fehling's test Correct answer.
  3. Molisch test
  4. Iodine test

Explanation

Fehling's test relies on the reduction of cupric ions to cuprous oxide by free aldehyde or ketone groups, which are present in reducing sugars but not in sucrose. Sucrose itself is non-reducing, so a positive Fehling's test indicates contamination with a reducing sugar such as glucose or fructose.

Question 4Pharmaceutical Chemistry

A drug substance shows a specific rotation of +52° when measured at 25°C with the sodium D-line. Which property of the molecule is being quantified?

  1. Optical rotation Correct answer.
  2. Refractive index
  3. Absorbance
  4. Fluorescence intensity

Explanation

Optical rotation is the angle through which plane-polarized light is rotated by a chiral substance, and specific rotation is that angle normalized to unit concentration and path length. It is used for identity and purity assessment of optically active drugs such as quinine and camphor.

Question 5Pharmaceutical Chemistry

Which spectral method is most appropriate for identifying an unknown functional group in a drug molecule through characteristic absorption bands at 1700 cm⁻¹ and 3300 cm⁻¹?

  1. Nuclear magnetic resonance spectroscopy
  2. Mass spectrometry
  3. Infrared spectroscopy Correct answer.
  4. Atomic absorption spectroscopy

Explanation

Infrared spectroscopy detects vibrational transitions of bonds, so characteristic bands at 1700 cm⁻¹ (carbonyl) and 3300 cm⁻¹ (hydroxyl or amine) are used for functional group identification. It is the standard identity test in pharmacopoeial monographs.

Question 6Pharmaceutical Chemistry

In a high-performance liquid chromatography assay for a basic drug, what is the main purpose of adding an ion-pairing reagent such as sodium heptane sulfonate to the mobile phase?

  1. To increase detector sensitivity by absorbing at the detection wavelength
  2. To act as a buffer to fix the pH of the mobile phase
  3. To suppress ionization and improve peak shape and retention of the basic analyte Correct answer.
  4. To reduce the column back-pressure by lowering viscosity

Explanation

Ion-pairing reagents form neutral complexes with ionized basic drugs, reducing peak tailing caused by secondary interaction with residual silanol groups and giving reproducible retention. The pair also controls retention by making the analyte behave more like a neutral species.

Question 7Pharmaceutical Chemistry

In a gas chromatographic assay of residual solvents in a drug substance, which detector is most suitable for detecting trace halogenated solvents?

  1. Electron capture detector Correct answer.
  2. Thermal conductivity detector
  3. Flame photometric detector
  4. Flame ionization detector

Explanation

The electron capture detector is highly selective and sensitive to electronegative species such as halogenated compounds, making it ideal for trace residual solvents of that class. Its response depends on the capture of electrons by the analyte, so it responds poorly to simple hydrocarbons.

Question 8Pharmaceutical Chemistry

A drug undergoes first-order degradation with a rate constant of 0.0231 per month. What is its shelf-life (t₉₀) to the nearest whole month?

  1. 10 months
  2. 5 months Correct answer.
  3. 3 months
  4. 30 months

Explanation

For a first-order reaction, t₉₀ equals 0.105 divided by the rate constant. With k equal to 0.0231 per month, t₉₀ is approximately 4.55 months, which rounds to 5 months.

Question 9Pharmaceutical Chemistry

Which statement best explains why a drug with a pKa of 8.4 is predominantly in its ionized form at physiological pH 7.4?

  1. Because the drug is neutral and is unaffected by pH
  2. Because the drug is a weak acid and donates a proton at pH below its pKa
  3. Because the drug is a weak base and accepts a proton at pH below its pKa Correct answer.
  4. Because the drug is a strong acid and is fully dissociated at any pH

Explanation

A pKa of 8.4 with ionization at pH 7.4 indicates a weak base, which becomes protonated and positively charged when the pH is below its pKa. The Henderson–Hasselbalch relationship predicts that at one unit below the pKa about 90% of the base is ionized.

Question 10Pharmaceutical Chemistry

Which type of reaction is most characteristic of the degradation of aspirin in the presence of moisture?

  1. Photochemical decarboxylation
  2. Racemization at a chiral centre
  3. Oxidation of the aromatic ring
  4. Hydrolysis of the ester linkage Correct answer.

Explanation

Aspirin is an ester of salicylic acid and acetic acid, and moisture catalyses hydrolysis of the ester bond to give salicylic acid and acetic acid. This is why aspirin tablets are formulated to minimize moisture and are tested for free salicylic acid.

Question 11Pharmaceutical Chemistry

During the assay of a drug by ultraviolet spectrophotometry, the absorbance of a 0.001% w/v solution in a 1 cm cell is 0.450. Given a molar absorptivity of 15000 L mol⁻¹ cm⁻¹ and a molecular weight of 300, what is the approximate concentration in mg per 100 mL?

  1. 0.9 mg/100 mL
  2. 90 mg/100 mL
  3. 0.09 mg/100 mL
  4. 9 mg/100 mL Correct answer.

Explanation

Using A = εbc, the molar concentration is 0.450 divided by 15000, which is 3.0 × 10⁻⁵ mol/L. Multiplying by the molecular weight of 300 gives 0.009 g/L, equivalent to 9 mg per 100 mL.

Question 12Pharmaceutical Chemistry

Which reagent is used in the limit test for iron in a pharmacopoeial monographs?

  1. Dithizone
  2. Silver nitrate
  3. Sodium sulphide
  4. Thioglycollic acid Correct answer.

Explanation

Thioglycollic acid reduces ferric iron to ferrous and forms a coloured complex with it in an ammoniacal citrate medium, allowing comparison with a standard iron solution. This is the classical limit test for iron in pharmacopoeial monographs.

Question 13Pharmaceutical Chemistry

Which technique is the most appropriate for separating and quantifying enantiomeric impurities in a chiral drug substance?

  1. Gas chromatography with a flame ionization detector
  2. Ion-exchange chromatography
  3. Normal-phase HPLC on silica
  4. Chiral HPLC using a cyclodextrin or amylose stationary phase Correct answer.

Explanation

Enantiomers have identical physical properties in an achiral environment, so a chiral selector immobilized on the stationary phase is required to form diastereomeric complexes and resolve them. Chiral HPLC with cyclodextrin or polysaccharide phases is the standard approach for enantiomeric purity.

Question 14Pharmaceutical Chemistry

Which of the following is the principal reason for using a deuterium lamp as the radiation source in UV spectrophotometry?

  1. It provides sharp line emission for atomic absorption
  2. It produces monochromatic light at a single wavelength
  3. It generates a high-intensity beam in the infrared region
  4. It emits a continuous spectrum in the ultraviolet region Correct answer.

Explanation

Deuterium lamps emit a continuous spectrum from about 160 to 400 nm, which is necessary for scanning and selecting wavelengths in the ultraviolet region. A continuous source is required because UV spectrophotometry uses a monochromator to isolate the desired wavelength.

Question 15Pharmaceutical Chemistry

A raw material sample is tested by the flame test and gives a brick-red colour. Which cation is most likely present?

  1. Calcium Correct answer.
  2. Sodium
  3. Barium
  4. Potassium

Explanation

Calcium salts impart a brick-red colour to a non-luminous flame because the excited electrons emit light at characteristic wavelengths. This is a simple and rapid preliminary identity test for the cation.

Question 16Pharmaceutical Chemistry

In the assay of a drug by potentiometry, a glass electrode is used as the indicator electrode. Which component of the glass electrode is responsible for its response to hydrogen ion activity?

  1. The silver-silver chloride internal reference
  2. The hydrated gel layer on the glass membrane Correct answer.
  3. The internal buffer solution
  4. The shielding of the electrode body

Explanation

A thin hydrated gel layer forms on the glass membrane and exchanges sodium ions for hydrogen ions, generating a potential that depends on the hydrogen ion activity of the test solution. This potential is measured against a reference electrode to give the pH or endpoint.

Question 17Pharmaceutical Chemistry

Which chemical test is used to distinguish a primary aromatic amine from an aliphatic amine by formation of a coloured azo dye?

  1. Tollens' test
  2. Liebermann's test
  3. Diazotization and coupling with β-naphthol Correct answer.
  4. Ninhydrin test

Explanation

Primary aromatic amines can be diazotized with nitrous acid at low temperature and then coupled with a phenol such as β-naphthol to form an intensely coloured azo dye. Aliphatic primary amines do not form stable diazonium salts, so the test is selective for aromatic amines.

Question 18Pharmaceutical Chemistry

Which chromatographic parameter is defined as the ratio of the distance travelled by the solute to the distance travelled by the solvent front in thin-layer chromatography?

  1. Retention factor (Rf) Correct answer.
  2. Resolution
  3. Capacity factor
  4. Retention time

Explanation

The retention factor is the ratio of the distance migrated by the solute to the distance migrated by the mobile phase front from the origin. It is used for identification in TLC because it is characteristic of a compound under defined conditions.

Question 19Pharmaceutical Chemistry

In the assay of a drug by redox titration with ceric ammonium sulphate, which indicator is commonly used?

  1. Ferroin Correct answer.
  2. Starch
  3. Methyl orange
  4. Phenolphthalein

Explanation

Ferroin is a redox indicator that changes from red to pale blue when the ferrous complex is oxidized to the ferric form, which occurs at the endpoint of ceric ammonium sulphate titrations. It is used because its transition potential matches that of the ceric-cerous couple.

Question 20Pharmaceutical Chemistry

Which statement about the relationship between partition coefficient and drug absorption is correct?

  1. A very low partition coefficient favours transmembrane permeation
  2. Partition coefficient has no influence on absorption
  3. An optimum partition coefficient balances lipid solubility and aqueous solubility for membrane permeation Correct answer.
  4. A very high partition coefficient always improves absorption by increasing solubility

Explanation

Absorption through membranes requires both lipophilic character for permeation and sufficient aqueous solubility for dissolution and transport to the membrane. Consequently an optimum partition coefficient exists, as expressed by the Hansch relationship, rather than a monotonic increase with lipophilicity.

Question 21Pharmaceutical Chemistry

Which pharmacopoeial test is used to detect the presence of heavy metals as their sulphide dispersions compared with a lead standard?

  1. Limit test for arsenic
  2. Limit test for chlorides
  3. Limit test for sulphates
  4. Limit test for heavy metals Correct answer.

Explanation

The heavy metal limit test precipitates metal sulphides in an acidic or ammoniacal medium and compares the brown colour with a lead standard solution treated identically. It is a general test that does not identify individual metals.

Question 22Pharmaceutical Chemistry

Which of the following is the correct order of the steps in a typical pharmacopoeial assay by non-aqueous titration of a weak base?

  1. Dissolve sample in ethanol, titrate with iodine, use starch indicator, calculate content
  2. Standardize perchloric acid, dissolve sample in glacial acetic acid, titrate potentiometrically, calculate content Correct answer.
  3. Dissolve sample in acetic acid, titrate with sodium hydroxide, use methyl orange, calculate content
  4. Dissolve sample in water, titrate with sodium hydroxide, use phenolphthalein, calculate content

Explanation

In non-aqueous titration of weak bases, perchloric acid in glacial acetic acid is standardized with potassium hydrogen phthalate, the sample is dissolved in glacial acetic acid, and the titration is followed potentiometrically to a sharp break. The volume consumed is then used to calculate the drug content from its equivalent weight.

Question 23Pharmaceutical Chemistry

Which of the following describes the purpose of the wavelength calibration test on a UV spectrophotometer using a holmium oxide or potassium dichromate solution?

  1. To check the absorbance linearity of the instrument
  2. To check the stray light level
  3. To measure the baseline noise
  4. To verify the accuracy of the wavelength scale Correct answer.

Explanation

Holmium oxide and potassium dichromate solutions have well-defined absorption maxima, so comparing observed maxima with the certified values confirms that the wavelength scale is accurate. This is a routine performance qualification test in pharmaceutical laboratories.

Question 24Pharmaceutical Chemistry

A drug is a weak acid with a pKa of 4.5. At which pH will it be approximately 50% ionized?

  1. pH 4.5 Correct answer.
  2. pH 6.5
  3. pH 2.5
  4. pH 7.4

Explanation

For a weak acid, the Henderson–Hasselbalch equation predicts that the acid is 50% ionized when the pH equals the pKa. At pH 4.5, the concentrations of unionized acid and conjugate base are equal.

Question 25Pharmaceutical Chemistry

Which of the following statements about the validation of an analytical method is correct according to ICH guidance?

  1. Precision is established by measuring a single sample once at the highest concentration
  2. Accuracy is assessed by comparing the method with a reference standard method over the full working range
  3. Specificity, accuracy, precision, linearity, range, detection and quantitation limits are typical validation characteristics Correct answer.
  4. Robustness is only required for methods used in early development

Explanation

ICH Q2 sets out the validation characteristics that should be evaluated for an assay, including specificity, accuracy, precision, linearity, range, and detection or quantitation limits where relevant. Each characteristic is demonstrated through a defined experimental design rather than a single measurement.

Question 26Pharmaceutical Chemistry

According to the Arrhenius equation as applied to pharmaceutical stability prediction, which factor is primarily responsible for the marked increase in degradation rate when a liquid formulation is stored at a higher temperature?

  1. Increase in the activation energy of the degradation reaction
  2. Decrease in the frequency of molecular collisions in solution
  3. Increase in the fraction of molecules possessing energy greater than the activation energy Correct answer.
  4. Reduction in the concentration of the reacting drug species

Explanation

The Arrhenius equation shows that the rate constant depends exponentially on temperature because a larger fraction of molecules acquires energy exceeding the activation energy barrier. Activation energy itself is essentially a property of the reaction pathway and does not rise with temperature. This exponential dependence is why accelerated stability studies at elevated temperature can be extrapolated to predict shelf-life at storage conditions.

Question 27Pharmaceutical Chemistry

In a pharmacopoeial limit test for chloride using silver nitrate in dilute nitric acid, what is the purpose of adding nitric acid to the test solution?

  1. To increase the solubility of silver chloride so that a clear opalescence forms
  2. To oxidise any reducing impurities present in the sample
  3. To precipitate silver chloride completely from the solution
  4. To prevent precipitation of silver salts of other anions such as carbonate and phosphate Correct answer.

Explanation

Dilute nitric acid keeps the medium acidic so that silver ions do not precipitate with anions such as carbonate, phosphate or sulphide, which would otherwise give a false turbidity. Only chloride (and bromide/iodide) then reacts with silver nitrate to produce the opalescence compared against a standard. The acid does not enhance precipitation but suppresses interference.

Question 28Pharmaceutical Chemistry

A weakly acidic drug has a pKa of 3.5. Using the Henderson–Hasselbalch relationship, what approximate percentage of the drug is ionised at pH 5.5 in the small intestine?

  1. 50%
  2. 9%
  3. 1%
  4. 99% Correct answer.

Explanation

For a weak acid, pH − pKa = log([ionised]/[unionised]). Here the difference is 2.0, so the ratio of ionised to unionised species is 100:1, meaning about 99% is ionised. This extensive ionisation at intestinal pH explains why such acids are absorbed mainly in the unionised form and why pH-partition concepts matter in formulation.

Question 29Pharmaceutical Chemistry

In the assay of a drug substance by non-aqueous titration using perchloric acid in glacial acetic acid, which solvent is typically used to dissolve a weak base before titration and why?

  1. Water, because it stabilises the titrant and sharpens the endpoint
  2. Glacial acetic acid, because it enhances the basicity of the analyte and gives a sharp potentiometric endpoint Correct answer.
  3. Ethanol, because it dissolves both polar and non-polar drugs equally
  4. Chloroform, because it suppresses dissociation of the perchloric acid titrant

Explanation

Glacial acetic acid is a protogenic solvent that levels weak bases to their fully protonated form, making them titratable with perchloric acid and producing a sharp endpoint. Water would compete as a base and flatten the titration curve. The choice of solvent therefore determines the feasibility and sharpness of the non-aqueous titration.

Question 30Pharmaceutical Chemistry

A candidate impurity in a drug substance is present at 0.04% and must be controlled at a limit of 0.10%. Which validation characteristic most directly establishes that the analytical procedure can reliably quantify the impurity at this level?

  1. Robustness of the method to small changes in pH
  2. Specificity of the method towards the drug substance
  3. Linearity of the detector response over the entire calibration range
  4. Limit of quantitation of the method Correct answer.

Explanation

The limit of quantitation defines the lowest concentration that can be measured with acceptable precision and accuracy, so it must be below the control limit of 0.10% for reliable quantification at 0.04%. Specificity confirms that the impurity signal is not from other components but does not establish quantifiability. Linearity and robustness support method performance but do not by themselves define the lowest reliable concentration.

Question 31Pharmaceutics / Dosage Form Design

In the design of a sustained-release matrix tablet using hydroxypropyl methylcellulose, which property of the polymer principally governs the rate of drug release from the swollen gel layer?

  1. The colour of the polymer powder
  2. The compressibility of the pure drug crystals
  3. The pH of the granulating fluid alone
  4. The viscosity grade and consequent gel-layer diffusional resistance Correct answer.

Explanation

Release from a hydrophilic matrix is controlled by hydration of the polymer to form a viscous gel barrier through which the drug must diffuse and from which it must dissolve. Higher-viscosity grades of HPMC produce a more resistant gel layer and slower release, so the viscosity grade is the key formulation variable. Compressibility and colour do not determine diffusional resistance once the gel forms.

Question 32Pharmaceutics / Dosage Form Design

Which excipient is added to a tablet formulation specifically to promote disintegration by drawing water into the tablet and causing the compact to swell and break apart?

  1. Purified talc
  2. Lactose monohydrate
  3. Magnesium stearate
  4. Croscarmellose sodium Correct answer.

Explanation

Disintegrants such as croscarmellose sodium act by wicking water and swelling rapidly, which ruptures the interparticle bonds of the compact. Magnesium stearate and talc are lubricants, and lactose is a diluent/filler.

Question 33Pharmaceutics / Dosage Form Design

A pharmacist must prepare a sterile ophthalmic solution that will be terminally sterilised in its final container. Which sterilization method is most appropriate for a heat-stable aqueous eye drop in a sealed multidose bottle?

  1. Ethylene oxide exposure
  2. Moist heat sterilization in an autoclave at 121 °C for 15 minutes Correct answer.
  3. Dry heat sterilization at 160 °C for 2 hours
  4. Membrane filtration through a 0.22 µm filter

Explanation

Terminal sterilization of an aqueous solution in its final sealed container is achieved by saturated steam under pressure, typically 121 °C for 15 minutes, which is both effective and compatible with water-based products. Dry heat is for glassware and oils, ethylene oxide for heat-labile devices, and filtration is aseptic processing rather than terminal sterilization.

Question 34Pharmaceutics / Dosage Form Design

According to the biopharmaceutics classification system, a drug with high aqueous solubility and high intestinal permeability is placed in which class, and what does this imply for its oral absorption?

  1. Class I, with absorption limited mainly by gastric emptying and dissolution Correct answer.
  2. Class III, with permeability-limited absorption
  3. Class II, with dissolution rate-limited absorption
  4. Class IV, with negligible oral absorption

Explanation

BCS Class I compounds dissolve readily and permeate well, so the rate and extent of absorption are governed largely by dissolution and gastric emptying rather than by solubility or membrane transport. Class II is low solubility/high permeability, Class III high solubility/low permeability, and Class IV low in both.

Question 35Pharmaceutics / Dosage Form Design

In a quality-by-design study of a wet-granulation process, granule porosity and binder concentration are varied and the resulting tablet tensile strength is measured. Which response describes the property being optimised?

  1. A critical quality attribute of the tablet Correct answer.
  2. A raw material specification of the binder supplier
  3. A cleaning validation limit for the equipment
  4. A critical process parameter of the granulator

Explanation

Tensile strength is a measurable property of the finished tablet that must be kept within limits for the product to perform, so it is a critical quality attribute. Porosity and binder concentration are process/material variables (potential critical process parameters) that influence that attribute, not the attribute itself.

Question 36Pharmaceutics / Dosage Form Design

Which mechanism best explains why a drug incorporated in a lipophilic suppository base is released slowly after rectal administration?

  1. Partitioning of the drug from the melted base into the aqueous rectal fluid Correct answer.
  2. Rapid dissolution of the base in rectal fluid
  3. Immediate ionization of the drug within the base
  4. Active secretion of the base by rectal mucosa

Explanation

A lipophilic base such as theobroma oil melts at body temperature, and the drug must partition from the oily phase into the aqueous mucosal fluid before absorption. A drug with high oil solubility partitions slowly, prolonging release; hydrophilic drugs conversely leave the base rapidly.

Question 37Pharmaceutics / Dosage Form Design

Which statement correctly describes the role of a hydroalcoholic vehicle in an elixir?

  1. It acts as an antioxidant to prevent oxidation
  2. It lowers the dielectric constant and improves dissolution of poorly water-soluble drugs Correct answer.
  3. It increases surface tension to aid wetting
  4. It raises the pH to stabilise acidic drugs

Explanation

Ethanol lowers the dielectric constant of the solvent system, reducing the solvation energy for many poorly water-soluble organic drugs and thereby increasing their solubility. It is not a surfactant, antioxidant, or pH-raising agent.

Question 38Pharmaceutics / Dosage Form Design

A cream is described as an oil-in-water emulsion. Which property is expected when it is applied to skin?

  1. It is anhydrous and contains no emulsifier
  2. It is a suspension of solid particles in oil only
  3. It spreads easily, is non-greasy and washable with water Correct answer.
  4. It is greasy and occlusive and difficult to wash off

Explanation

In an oil-in-water cream the continuous phase is water, so the product spreads readily, feels less greasy, and is easily removed by washing. The greasy, occlusive, poorly washable behaviour belongs to water-in-oil creams and ointments.

Question 39Pharmaceutics / Dosage Form Design

In the design of an osmotic pump tablet, which component determines the rate at which drug is delivered?

  1. The colour of the semipermeable membrane
  2. The size of the tablet logo
  3. The hardness of the drug core alone
  4. The osmotic pressure gradient and the water permeability and thickness of the membrane Correct answer.

Explanation

Osmotic delivery is governed by water influx across the semipermeable membrane, which depends on the osmotic pressure difference between core and environment and on the membrane's water permeability and thickness. Drug release is therefore essentially independent of gastrointestinal pH and motility. Core hardness and cosmetic features do not set the delivery rate.

Question 40Pharmaceutics / Dosage Form Design

Which test is specified for evaluating the content uniformity of a batch of tablets containing a low-dose, potent drug?

  1. Hardness testing with a Monsanto tester
  2. Disintegration time in water at 37 °C
  3. Friability testing in a Roche drum
  4. Assay of ten individual tablets with acceptance by acceptance value limits Correct answer.

Explanation

Content uniformity is assessed by assaying individual tablets and evaluating the results against the acceptance value (or uniformity of dosage units) criteria in the pharmacopoeia. Friability, hardness, and disintegration are physical tests and do not measure the amount of drug per unit.

Question 41Pharmaceutics / Dosage Form Design

A drug has a hepatic extraction ratio close to 1. What is the principal consequence for its oral bioavailability?

  1. Oral bioavailability approaches zero because of extensive first-pass metabolism Correct answer.
  2. Oral bioavailability increases in proportion to liver enzyme activity
  3. Oral bioavailability is unaffected by hepatic blood flow
  4. Oral bioavailability approaches 100 percent because hepatic clearance is high

Explanation

When the hepatic extraction ratio approaches unity, almost all drug reaching the liver in the portal circulation is removed during the first pass, so the fraction reaching systemic circulation is very small. Bioavailability is therefore low and highly dependent on hepatic blood flow and enzyme activity, not independent of them.

Question 42Pharmaceutics / Dosage Form Design

Which factor most directly increases the deposition of inhaled particles in the alveolar region of the lung?

  1. Reducing the mass median aerodynamic diameter to about 1 to 3 µm Correct answer.
  2. Increasing the inspiratory flow rate to maximum
  3. Increasing the mass median aerodynamic diameter to above 10 µm
  4. Increasing the particle density while keeping geometric size constant

Explanation

Alveolar deposition is favoured by particles with a mass median aerodynamic diameter of roughly 1 to 3 µm, which can bypass impaction in the upper airways and sediment in the deep lung. Larger particles impact in the oropharynx, and very high flow rates promote upper-airway impaction.

Question 43Pharmaceutics / Dosage Form Design

In the preparation of a suspension, which excipient is included to prevent irreversible caking by forming a structured, thixotropic vehicle?

  1. A buffer such as citrate
  2. A colourant such as tartrazine
  3. A suspending agent such as xanthan gum Correct answer.
  4. A chelating agent such as disodium edetate

Explanation

Suspending agents are hydrophilic polymers or clays that increase vehicle viscosity and form a structured, often thixotropic, network that slows settling and resists caking on standing. Chelating agents, buffers, and colourants serve unrelated functions.

Question 44Pharmaceutics / Dosage Form Design

A hard gelatin capsule shell is plasticised with glycerin and stored at high humidity. What is the most likely consequence for the filled powder?

  1. The shell softens and may become tacky, altering dissolution behaviour Correct answer.
  2. The shell cross-links and becomes insoluble in gastric fluid
  3. The shell dissolves in the stomach more rapidly
  4. The shell becomes brittle and cracks immediately

Explanation

Glycerin is a plasticiser that absorbs moisture, so at high humidity the shell softens and may become sticky, which can delay or alter capsule opening and dissolution. Brittleness results from low humidity and loss of moisture, not from high humidity with a plasticiser.

Question 45Pharmaceutics / Dosage Form Design

Which statement about the use of a superdisintegrant in an orally disintegrating tablet is correct?

  1. It must melt at body temperature to release the drug
  2. It must dissolve completely to form a viscous solution
  3. It must be hydrophobic to repel saliva
  4. It must be insoluble and swell rapidly to rupture the tablet within seconds in the mouth Correct answer.

Explanation

Orally disintegrating tablets rely on superdisintegrants that are insoluble, wick water rapidly, and swell strongly so the compact breaks apart within seconds in the small volume of saliva available. Soluble viscous polymers would form a gel and slow disintegration, and hydrophobicity or melting is not the mechanism.

Question 46Pharmaceutics / Dosage Form Design

In a transdermal patch of the reservoir type, which layer controls the rate at which drug reaches the skin?

  1. The release liner
  2. The adhesive overlay alone
  3. The backing film
  4. The rate-controlling microporous membrane Correct answer.

Explanation

In a reservoir patch the drug solution or gel is separated from the skin by a rate-controlling membrane whose permeability determines the delivery rate. The backing is impermeable and occlusive, the release liner is removed before use, and the adhesive fixes the patch without being the primary rate limiter.

Question 47Pharmaceutics / Dosage Form Design

A manufacturer wishes to convert a conventional immediate-release tablet into a delayed-release product targeted to the colon. Which approach is most suitable?

  1. Coating with a pH-sensitive polymer designed to dissolve at colonic pH combined with a time delay Correct answer.
  2. Applying an enteric coat that dissolves only above pH 7
  3. Incorporating a superdisintegrant into the core
  4. Compression coating with a thick insoluble polymer layer

Explanation

Colon targeting exploits the rise in pH along the gastrointestinal tract together with transit time, so a polymer that dissolves at colonic pH and also provides a lag time is used. A simple enteric coat dissolves in the small intestine, an insoluble compression coat alone gives poorly controlled release, and a superdisintegrant promotes immediate release.

Question 48Pharmaceutics / Dosage Form Design

Which parameter is directly obtained from the slope of a plot of the logarithm of plasma concentration versus time during the terminal elimination phase?

  1. The apparent volume of distribution
  2. The absorption rate constant
  3. The bioavailability fraction
  4. The elimination rate constant Correct answer.

Explanation

During the terminal phase, concentration declines exponentially, so a semilogarithmic plot is linear with a slope equal to minus the elimination rate constant divided by 2.303. Volume of distribution and bioavailability are derived from dose and area under the curve, and the absorption constant comes from the rising phase.

Question 49Pharmaceutics / Dosage Form Design

Which unit operation is used to reduce the particle size of a drug powder by impact and attrition in a high-speed rotating chamber?

  1. Fluid energy milling
  2. Lyophilisation
  3. Ball milling Correct answer.
  4. Spray drying

Explanation

A ball mill reduces particle size by impact and attrition as grinding media tumble within a rotating chamber. Fluid energy milling uses high-velocity gas jets, spray drying forms particles from droplets, and lyophilisation removes water by sublimation; none of these is a rotating-chamber impact-and-attrition mill.

Question 50Pharmaceutics / Dosage Form Design

In a quality control laboratory, a tablet batch fails the friability test with excessive weight loss. Which formulation change is most likely to correct the problem?

  1. Adding more disintegrant
  2. Reducing the tablet weight
  3. Increasing the binder concentration or compression force Correct answer.
  4. Increasing the proportion of magnesium stearate

Explanation

Excessive friability indicates weak interparticle bonding, which can be improved by increasing binder level or compression force to strengthen the compact. More lubricant weakens bonding further, extra disintegrant can increase fragility, and reducing tablet weight does not address the underlying weakness.