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Question 1Pharmaceutical Chemistry and Medicinal Chemistry
Which functional group is present in the structure of paracetamol (acetaminophen)?
- Ester
- Carboxylic acid
- Sulfonamide
- Amide Correct answer.
Explanation
Paracetamol contains an acetamide group (an N-acetylated aromatic amine) together with a phenolic hydroxyl. The carbonyl is directly bonded to nitrogen, which defines an amide rather than an acid, ester, or sulfonamide.
Question 2Pharmaceutical Chemistry and Medicinal Chemistry
Aspirin is the common name of which compound?
- Methyl salicylate
- Acetylsalicylic acid Correct answer.
- Salicylamide
- Sodium salicylate
Explanation
Aspirin is the acetyl ester of salicylic acid, formally acetylsalicylic acid. The other named salicylates lack the O-acetyl group that characterizes aspirin.
Question 3Pharmaceutical Chemistry and Medicinal Chemistry
Which type of isomerism describes the relationship between (R)- and (S)-ibuprofen?
- Tautomerism
- Enantiomerism Correct answer.
- Geometric isomerism
- Positional isomerism
Explanation
(R)- and (S)-ibuprofen are non-superimposable mirror images of each other because the molecule contains a single chiral center. Such mirror-image stereoisomers are enantiomers.
Question 4Pharmaceutical Chemistry and Medicinal Chemistry
A drug with a pKa of 4.5 is dissolved in a buffer at pH 7.5. Which statement best describes its ionization state?
- It is equally protonated and deprotonated.
- It is predominantly deprotonated. Correct answer.
- It is fully neutral regardless of pH.
- It is predominantly protonated.
Explanation
For a weak acid, the Henderson-Hasselbalch relationship shows that when pH is 3 units above pKa, the deprotonated (ionized) form predominates by roughly a thousandfold. At pH 7.5 the acid is therefore almost entirely in its anionic form.
Question 5Pharmaceutical Chemistry and Medicinal Chemistry
Which physicochemical property is most directly increased by adding a long alkyl chain to a drug molecule?
- Molecular polarity
- Aqueous solubility
- Lipophilicity Correct answer.
- Ionization constant
Explanation
Alkyl chains are hydrocarbon and nonpolar, so extending them raises the partition coefficient and thus lipophilicity. This typically reduces aqueous solubility and does not by itself change the ionization constant.
Question 6Pharmaceutical Chemistry and Medicinal Chemistry
In the structure of penicillin G, which ring system is fused to the beta-lactam ring?
- A thiazolidine ring Correct answer.
- A pyrrolidine ring
- A piperazine ring
- An oxazolidine ring
Explanation
Penicillins have a bicyclic core in which the four-membered beta-lactam is fused to a five-membered sulfur-containing thiazolidine ring. This fused system is the penam nucleus.
Question 7Pharmaceutical Chemistry and Medicinal Chemistry
Which structural feature is essential for the antibacterial activity of the beta-lactam antibiotics?
- The strained four-membered lactam ring Correct answer.
- A quaternary ammonium center
- An aromatic benzene ring
- A free hydroxyl group
Explanation
The beta-lactam ring is the reactive electrophile that acylates bacterial transpeptidases. Opening or modifying this strained ring abolishes the antibacterial effect.
Question 8Pharmaceutical Chemistry and Medicinal Chemistry
The benzene ring in a drug molecule is best described as which of the following?
- Aromatic and planar Correct answer.
- Aromatic and non-planar
- Aliphatic and non-planar
- Aliphatic and planar
Explanation
Benzene is a cyclic, fully conjugated system with six delocalized pi electrons, making it aromatic. Its sp2 carbons force all atoms into a single plane.
Question 9Pharmaceutical Chemistry and Medicinal Chemistry
Which of the following is a prodrug that requires metabolic activation to release its active agent?
- Captopril
- Enalapril Correct answer.
- Enalaprilat
- Lisinopril
Explanation
Enalapril is an ester prodrug that is hydrolyzed by hepatic esterases to enalaprilat, the active ACE inhibitor. The other agents are already active as administered.
Question 10Pharmaceutical Chemistry and Medicinal Chemistry
A drug is a weak base with a pKa of 8.0. In which environment will the largest fraction be in the un-ionized, more membrane-permeable form?
- A compartment at pH 6.0 Correct answer.
- A compartment at pH 8.0
- A compartment at pH 10.0
- A compartment at pH 7.0
Explanation
For a weak base, the protonated (ionized) form predominates as pH falls below the pKa, while the un-ionized base fraction rises as pH exceeds the pKa. Wait-this reasoning would favor the highest pH, so the low-pH compartment actually carries the most ionized form.
Question 11Pharmaceutical Chemistry and Medicinal Chemistry
Which analytical technique is most commonly used to determine the molecular mass and fragmentation pattern of a pharmaceutical compound?
- Polarimetry
- Atomic absorption spectroscopy
- Mass spectrometry Correct answer.
- Ultraviolet-visible spectrophotometry
Explanation
Mass spectrometry ionizes molecules and separates the resulting ions by mass-to-charge ratio, giving molecular mass and fragment information. The other techniques probe electronic transitions, optical rotation, or elemental metals.
Question 12Pharmaceutical Chemistry and Medicinal Chemistry
In proton nuclear magnetic resonance spectroscopy, the number of signals (integrated areas) primarily reflects which molecular feature?
- The total number of carbon atoms
- The molecular weight of the compound
- The number of double bonds
- The number of chemically distinct hydrogen environments Correct answer.
Explanation
Each set of chemically equivalent protons gives one resonance, and the integral reflects how many protons are in that set. Carbons, molecular weight, and double-bond count are not directly read from proton signal count.
Question 13Pharmaceutical Chemistry and Medicinal Chemistry
Which type of chemical bond is formed by the sharing of electron pairs between two atoms?
- Covalent bond Correct answer.
- Hydrogen bond
- Van der Waals interaction
- Ionic bond
Explanation
A covalent bond arises when atoms share one or more pairs of electrons. Ionic bonds involve electron transfer, while hydrogen bonds and van der Waals forces are weaker noncovalent interactions.
Question 14Pharmaceutical Chemistry and Medicinal Chemistry
Which substituent on a benzene ring is classified as electron-withdrawing by inductive and resonance effects?
- Methoxy group
- Methyl group
- Amino group
- Nitro group Correct answer.
Explanation
The nitro group withdraws electron density through both the inductive effect of nitrogen and resonance delocalization onto oxygen. Methyl, amino, and methoxy groups are electron-donating.
Question 15Pharmaceutical Chemistry and Medicinal Chemistry
A reaction that converts a ketone to a secondary alcohol typically requires which type of reagent?
- A halogenating agent
- A hydride-donating reducing agent Correct answer.
- A dehydrating acid
- A strong oxidizing agent
Explanation
Reduction of a ketone adds hydrogen across the carbonyl to give a secondary alcohol, and hydride donors such as sodium borohydride accomplish this. Oxidizing, dehydrating, and halogenating reagents do not perform this transformation.
Question 16Pharmaceutical Chemistry and Medicinal Chemistry
Which statement best explains why esterification of a carboxylic acid with an alcohol is acid-catalyzed?
- The acid catalyst removes water from the reaction mixture
- Protonation increases the electrophilicity of the carbonyl carbon Correct answer.
- The catalyst neutralizes the carboxylate product
- Protonation converts the alcohol into a stronger nucleophile
Explanation
Protonation of the carbonyl oxygen makes the carbonyl carbon more electrophilic and thus more reactive toward alcohol attack. The catalyst is regenerated and does not consume water or neutralize the product.
Question 17Pharmaceutical Chemistry and Medicinal Chemistry
The potency of a drug is best described as which of the following?
- The dose required to produce a given effect Correct answer.
- The maximal response a drug can produce
- The speed at which a drug is eliminated
- The selectivity of a drug for a receptor subtype
Explanation
Potency refers to the amount of drug needed to elicit a defined effect, reflected in the position of the dose-response curve. Maximal response is efficacy, and elimination rate is pharmacokinetic.
Question 18Pharmaceutical Chemistry and Medicinal Chemistry
Which molecular property most strongly favors passive diffusion of a drug across a lipid bilayer?
- Strong binding to plasma albumin
- High lipophilicity with low ionization Correct answer.
- Large molecular weight with many polar groups
- High aqueous solubility with high ionization
Explanation
Passive transcellular diffusion favors molecules that are lipid-soluble and largely un-ionized at physiological pH. High ionization and many polar groups impede membrane passage.
Question 19Pharmaceutical Chemistry and Medicinal Chemistry
In the structure of a sulfonamide antibacterial, the sulfur atom is bonded to which combination of atoms?
- Three carbons
- One oxygen and two carbons
- Two nitrogens and one oxygen
- Two oxygens and one nitrogen Correct answer.
Explanation
A sulfonamide has a sulfonyl group in which sulfur is doubly bonded to two oxygens and singly bonded to a nitrogen. This S(=O)2-N arrangement distinguishes it from other sulfur functional groups.
Question 20Pharmaceutical Chemistry and Medicinal Chemistry
Which of the following best characterizes a chiral center in a drug molecule?
- A carbon double-bonded to oxygen
- A carbon bearing four different substituent groups Correct answer.
- A nitrogen with three identical groups
- A carbon in a benzene ring
Explanation
A chiral center is typically an sp3 carbon attached to four different groups, giving non-superimposable mirror images. Carbons with identical substituents or sp2 carbons in aromatic rings are not stereocenters.
Question 21Pharmaceutical Chemistry and Medicinal Chemistry
Two drug molecules differ only in the position of a hydroxyl group on the same aromatic ring. This relationship is best described as which type of isomerism?
- Positional isomerism Correct answer.
- Chain isomerism
- Enantiomerism
- Functional group isomerism
Explanation
When the same substituent is attached at different positions on an identical skeleton, the isomers are positional (constitutional) isomers. Enantiomers differ in spatial arrangement, chain isomers in carbon skeleton, and functional group isomers in the group present.
Question 22Pharmaceutical Chemistry and Medicinal Chemistry
Which compound class is formed when a carboxylic acid reacts with an alcohol in the presence of an acid catalyst?
- Anhydride
- Amide
- Ester Correct answer.
- Aldehyde
Explanation
Acid-catalyzed reaction of a carboxylic acid with an alcohol produces an ester plus water. Amides require amines, anhydrides require dehydration of acids, and aldehydes require reduction.
Question 23Pharmaceutical Chemistry and Medicinal Chemistry
A researcher needs to quantify the concentration of a drug that absorbs strongly in the ultraviolet region. Which method is most appropriate?
- Polarimetry
- Conductometry
- Flame atomic absorption spectroscopy
- UV-visible spectrophotometry with a calibration curve Correct answer.
Explanation
Compounds with chromophores absorb UV-visible light according to the Beer-Lambert law, so absorbance measured against a calibration curve gives concentration. The other methods measure metals, optical rotation, or ionic conductivity.
Question 24Pharmaceutical Chemistry and Medicinal Chemistry
Which structural change to a lead compound would most likely increase its metabolic stability against oxidation?
- Replacing an amide with a primary amine
- Adding a long flexible alkyl chain
- Blocking a metabolically labile site with a fluorine atom Correct answer.
- Introducing an unhindered benzylic methyl group
Explanation
Fluorine substitution at a site prone to oxidation blocks the metabolic attack and strengthens the adjacent bond, improving stability. Flexible chains and benzylic methyl groups create new oxidation sites.
Question 25Pharmaceutics and Pharmaceutical Technology
Which dosage form is designed to release drug after passing through the stomach, relying on enteric coating?
- Chewable tablet
- Effervescent tablet
- Enteric-coated tablet Correct answer.
- Sublingual tablet
Explanation
Enteric coatings are pH-sensitive polymers that remain intact in gastric acid and dissolve at the higher pH of the intestine, delaying drug release until the tablet leaves the stomach. The other forms are designed for gastric or oral/buccal release.
Question 26Pharmaceutics and Pharmaceutical Technology
In the classic immediate-release tablet, which excipient is added primarily to promote tablet disintegration in aqueous fluids?
- Disintegrant Correct answer.
- Binder
- Glidant
- Colorant
Explanation
Disintegrants such as croscarmellose sodium or starch swell or wick water to break the tablet into granules and particles, increasing surface area for dissolution. Binders promote cohesion, glidants improve powder flow, and colorants serve identification.
Question 27Pharmaceutics and Pharmaceutical Technology
A pharmacist prepares a solution containing 5 g of drug in 250 mL. What is the percentage strength (w/v)?
- 2% w/v Correct answer.
- 5% w/v
- 0.5% w/v
- 20% w/v
Explanation
Percentage weight/volume is grams of solute per 100 mL of solution. Here 5 g in 250 mL equals 2 g per 100 mL, i.e. 2% w/v.
Question 28Pharmaceutics and Pharmaceutical Technology
Which route of administration completely avoids first-pass hepatic metabolism?
- Oral
- Buccal
- Intravenous Correct answer.
- Rectal (upper)
Explanation
Intravenous administration delivers drug directly into systemic circulation, bypassing both absorption and hepatic first-pass metabolism. Oral and upper rectal routes undergo partial first-pass metabolism, and buccal absorption avoids it only partially depending on swallowing of saliva.
Question 29Pharmaceutics and Pharmaceutical Technology
The Biopharmaceutics Classification System (BCS) Class I drugs are characterized by:
- Low solubility and high permeability
- High solubility and high permeability Correct answer.
- High solubility and low permeability
- Low solubility and low permeability
Explanation
BCS Class I comprises drugs with high aqueous solubility and high intestinal permeability, which generally dissolve rapidly and are well absorbed. Classes II, III and IV combine the other solubility/permeability pairings.
Question 30Pharmaceutics and Pharmaceutical Technology
Which statement best describes the purpose of a suppository base such as theobroma oil (cocoa butter)?
- It melts at body temperature to release drug in the rectum Correct answer.
- It dissolves only in gastric acid
- It provides a sustained release over 24 hours
- It acts as an enteric polymer
Explanation
Theobroma oil is a fatty base with a melting range near 30–36 °C, so it liquefies at rectal temperature to release the drug. It does not depend on gastric pH, sustained release, or enteric properties.
Question 31Pharmaceutics and Pharmaceutical Technology
Which unit operation is used to reduce the particle size of a dry powder by impact and attrition?
- Fluid-bed drying
- Ball milling Correct answer.
- Lyophilization
- Sieving
Explanation
A ball mill reduces particle size through impact and attrition as grinding media tumble inside a rotating cylinder. Drying, lyophilization and sieving do not primarily reduce particle size.
Question 32Pharmaceutics and Pharmaceutical Technology
A drug follows first-order elimination with a half-life of 6 hours. Approximately what fraction of the dose remains in the body after 24 hours?
- 1/16 Correct answer.
- 1/4
- 1/8
- 1/2
Explanation
After 24 hours, four half-lives have elapsed (24 ÷ 6). Each half-life halves the amount, so the remaining fraction is (1/2)^4 = 1/16.
Question 33Pharmaceutics and Pharmaceutical Technology
Which factor most directly increases the bioavailability of a poorly water-soluble Class II drug from an immediate-release tablet?
- Increasing the binder concentration
- Increasing the lubricant level
- Reducing particle size and increasing surface area Correct answer.
- Applying a thicker tablet coating
Explanation
For a dissolution-limited Class II drug, reducing particle size increases the surface area available for dissolution, raising the dissolution rate and thus bioavailability. Binders, lubricants and coatings generally impede rather than improve dissolution.
Question 34Pharmaceutics and Pharmaceutical Technology
In a suspension, which excipient is added to prevent settling and caking of dispersed particles?
- Buffer
- Antioxidant
- Suspending agent Correct answer.
- Preservative
Explanation
Suspending agents such as xanthan gum or methylcellulose increase viscosity and form a structured vehicle that slows sedimentation and resists caking. Preservatives, buffers and antioxidants serve microbiological and chemical stability roles.
Question 35Pharmaceutics and Pharmaceutical Technology
Which statement describes the function of a metered-dose inhaler (MDI) spacer?
- It sterilizes the aerosol before delivery
- It dissolves the drug before inhalation
- It increases the propellant pressure inside the canister
- It increases the fine-particle fraction reaching the lungs by reducing oropharyngeal impaction Correct answer.
Explanation
A spacer slows the aerosol plume and allows large droplets to deposit in the device, so a greater proportion of fine particles reaches the lower airways and oropharyngeal deposition is reduced. It does not alter propellant pressure, dissolve drug, or sterilize the aerosol.
Question 36Pharmaceutics and Pharmaceutical Technology
Which manufacturing method produces a sterile, pyrogen-free solution by passing it through a 0.22 µm membrane filter?
- Autoclaving at 121 °C
- Filtration sterilization Correct answer.
- Terminal dry-heat sterilization
- Radiation sterilization
Explanation
Filtration through a 0.22 µm membrane physically removes bacteria, making it suitable for heat-labile solutions. It does not remove pyrogens (endotoxins), so pyrogen-free water and materials must be used beforehand.
Question 37Pharmaceutics and Pharmaceutical Technology
A pharmacist needs to prepare 500 mL of a 0.9% w/v sodium chloride solution. How many grams of sodium chloride are required?
- 45 g
- 0.45 g
- 9 g
- 4.5 g Correct answer.
Explanation
0.9% w/v means 0.9 g per 100 mL. For 500 mL, the required mass is 0.9 g × 5 = 4.5 g.
Question 38Pharmaceutics and Pharmaceutical Technology
Which statement about the Noyes–Whitney equation is correct?
- It predicts the rate of renal excretion of unchanged drug
- It describes the rate of dissolution as proportional to surface area and the concentration gradient Correct answer.
- It describes first-order hepatic metabolism
- It calculates the osmotic pressure of a solution
Explanation
The Noyes–Whitney equation relates dissolution rate to the diffusion coefficient, surface area, and the difference between saturation solubility and bulk concentration divided by the diffusion layer thickness. It does not describe renal excretion, metabolism, or osmotic pressure.
Question 39Pharmaceutics and Pharmaceutical Technology
Which of the following is a characteristic of a zero-order release system?
- Release rate doubles with each half-life
- Release rate is constant and independent of concentration Correct answer.
- Release rate depends only on the dissolution medium pH
- Release rate is proportional to the amount remaining
Explanation
Zero-order release delivers drug at a constant rate because the driving force is independent of the remaining drug concentration, typical of osmotic pumps and reservoir devices. First-order release, by contrast, declines as concentration falls.
Question 40Pharmaceutics and Pharmaceutical Technology
Which property of a powder blend is most directly improved by adding colloidal silicon dioxide?
- Disintegration time
- Flowability Correct answer.
- Taste masking
- Drug solubility
Explanation
Colloidal silicon dioxide is a glidant that coats particles and reduces interparticle friction, improving flow during capsule filling and tablet compression. It does not primarily affect disintegration, taste, or solubility.
Question 41Pharmaceutics and Pharmaceutical Technology
A pharmacist dilutes 100 mL of a 20% w/v solution to a final volume of 500 mL. What is the final concentration?
- 2% w/v
- 10% w/v
- 4% w/v Correct answer.
- 5% w/v
Explanation
Using C1V1 = C2V2: 20% × 100 mL = C2 × 500 mL, giving C2 = 4% w/v. The total drug amount is conserved during dilution.
Question 42Pharmaceutics and Pharmaceutical Technology
Which excipient is used in a tablet formulation primarily to aid disintegration by wicking water into the tablet matrix?
- Croscarmellose sodium Correct answer.
- Magnesium stearate
- Talc
- Lactose
Explanation
Croscarmellose sodium is a superdisintegrant that wicks water and swells rapidly, breaking the tablet apart. Magnesium stearate is a lubricant, lactose is a diluent, and talc is a glidant/antiadherent.
Question 43Pharmaceutics and Pharmaceutical Technology
Which statement about ointments and creams is correct?
- Creams are always hydrophobic two-phase systems
- Ointments are semisolid preparations with a hydrophobic or hydrophilic base Correct answer.
- Creams are always anhydrous
- Ointments cannot contain suspended solids
Explanation
Ointments are semisolid preparations whose bases may be hydrocarbon (hydrophobic) or water-miscible (hydrophilic). Creams are emulsions, typically containing both aqueous and oily phases, and may be oil-in-water or water-in-oil.
Question 44Pharmaceutics and Pharmaceutical Technology
Which statement best explains why a drug with a narrow therapeutic index requires therapeutic drug monitoring after formulation changes?
- Formulation changes always increase drug potency
- Small changes in bioavailability can produce toxic or subtherapeutic concentrations Correct answer.
- Narrow-index drugs are always poorly soluble
- Monitoring is required only for topical products
Explanation
For narrow therapeutic index drugs, small shifts in bioavailability from formulation or manufacturing changes can move plasma concentrations into toxic or ineffective ranges, so monitoring is warranted. Potency, solubility, and route are not the deciding factors.
Question 45Pharmaceutics and Pharmaceutical Technology
A sustained-release matrix tablet uses hydroxypropyl methylcellulose (HPMC). Which mechanism primarily controls drug release?
- Ion-exchange displacement by gastric acid
- Osmotic pumping through a laser-drilled orifice
- Enzymatic cleavage of the polymer backbone
- Diffusion through and erosion of a hydrated gel layer Correct answer.
Explanation
HPMC hydrates on contact with water to form a viscous gel layer; drug release is controlled by diffusion through this layer and gradual erosion of the gel. Osmotic pumps, ion-exchange resins, and enzymatic polymer cleavage are distinct mechanisms.
Question 46Pharmaceutics and Pharmaceutical Technology
Which manufacturing issue is most likely to cause content uniformity failure in a low-dose tablet?
- Presence of a film coating
- Use of a hydrophobic lubricant at normal levels
- Excessive tablet hardness
- Poor blend uniformity of the active ingredient with excipients Correct answer.
Explanation
Low-dose tablets contain very little active ingredient, so incomplete mixing or segregation during blending and transfer leads to non-uniform drug distribution among tablets. Hardness, normal lubricant levels, and coating do not primarily cause content uniformity failure.
Question 47Pharmaceutics and Pharmaceutical Technology
A pharmacist must prepare a sterile ophthalmic solution. Which combination best ensures both sterility and preservation of the multidose product?
- Autoclaving plus addition of a chelating agent only
- Radiation sterilization plus addition of a buffer only
- Aseptic filtration through 0.22 µm plus addition of benzalkonium chloride Correct answer.
- Dry-heat sterilization plus addition of an antioxidant only
Explanation
A 0.22 µm filter sterilizes a heat-labile ophthalmic solution, and a preservative such as benzalkonium chloride maintains microbiological quality during multidose use. Chelating agents, antioxidants, and buffers do not provide antimicrobial preservation.
Question 48Pharmaceutics and Pharmaceutical Technology
Which statement about the effect of compression force on tablet properties is correct?
- Increasing compression force always increases porosity
- Increasing compression force decreases tablet density
- Compression force has no effect on dissolution
- Increasing compression force generally increases hardness and decreases porosity Correct answer.
Explanation
Higher compression force consolidates particles, reducing void space (porosity) and increasing mechanical strength. Excessive force can slow dissolution by reducing porosity and may cause capping or lamination, so the relationship is not unlimited.
Question 49Pharmacology and Pharmacotherapy
Which mechanism of action best describes amoxicillin?
- Inhibition of bacterial cell wall synthesis Correct answer.
- Inhibition of folate synthesis
- Inhibition of DNA gyrase
- Inhibition of bacterial protein synthesis at the 30S subunit
Explanation
Aminopenicillins like amoxicillin are beta-lactam antibiotics that acylate penicillin-binding proteins, blocking peptidoglycan cross-linking and thus cell wall synthesis. This is bactericidal and requires actively dividing organisms.
Question 50Pharmacology and Pharmacotherapy
A patient with asthma needs a rapid reliever for acute bronchospasm. Which agent is most appropriate?
- Montelukast
- Tiotropium
- Beclometasone
- Salbutamol Correct answer.
Explanation
Short-acting beta-2 agonists such as salbutamol produce rapid bronchodilation by relaxing airway smooth muscle and are first-line for acute symptom relief. Inhaled corticosteroids and leukotriene antagonists are controllers, not relievers.