According to the Biopharmaceutics Classification System (BCS), a Class II drug is characterized by:
A
High solubility and high permeability
B
Low solubility and high permeability
✓ Correct
C
High solubility and low permeability
D
Low solubility and low permeability
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Step-by-Step Explanation & Concept Rationale
Class I = High Solubility/High Permeability; Class II = Low Solubility/High Permeability; Class III = High Solubility/Low Permeability; Class IV = Low Solubility/Low Permeability.
The rate of dissolution of a solid drug in a solvent is quantitatively described by which equation?
A
Henderson-Hasselbalch equation
B
Noyes-Whitney equation
✓ Correct
C
Michaelis-Menten equation
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Step-by-Step Explanation & Concept Rationale
The Noyes-Whitney equation (dC/dt = DA(Cs - C)/h) describes the rate of dissolution of spherical solid particles in a diffusion layer.
The partial or complete separation of the top or bottom crowns of a tablet from the main body is termed:
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Step-by-Step Explanation & Concept Rationale
Capping is the partial or complete detachment of the top or bottom face of a tablet from the main body due to air entrapment during compression.
Which mathematical law governs the sedimentation rate of particles in a pharmaceutical suspension?
A
Fick's first law of diffusion
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Step-by-Step Explanation & Concept Rationale
Stokes' Law determines the sedimentation velocity (v) of spherical particles suspended in a liquid medium under the influence of gravity.
In emulsion formulation, a surfactant with a Hydrophile-Lipophile Balance (HLB) value of 3 to 6 is best suited as a:
B
Water-in-oil (w/o) emulsifier
✓ Correct
C
Oil-in-water (o/w) emulsifier
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Step-by-Step Explanation & Concept Rationale
Surfactants with low HLB values (3-6) are lipophilic and favor water-in-oil (w/o) emulsions, whereas high HLB values (8-16) favor oil-in-water (o/w) emulsions.
Which tablet coating defect is characterized by an uneven distribution of color on the tablet surface?
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Step-by-Step Explanation & Concept Rationale
Mottling is an unequal distribution of coloring on a tablet surface with light or dark spots appearing on a uniform background.
Which of the following excipients is primarily used as a superdisintegrant in solid oral dosage forms?
A
Microcrystalline cellulose
B
Crosscarmellose sodium
✓ Correct
💡
Step-by-Step Explanation & Concept Rationale
Crosscarmellose sodium, sodium starch glycolate, and crospovidone are superdisintegrants that rapidly swell upon contact with water to break tablets apart.
Which official test assesses the physical strength of tablets against mechanical shock and abrasion during manufacturing and shipping?
B
Friability test
✓ Correct
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Step-by-Step Explanation & Concept Rationale
Friability testing, performed using a Roche friabilator, measures weight loss (standard limit is normally < 1.0%) after tumbling tablets at 25 rpm for 4 minutes (100 revolutions).
The bacterial endotoxin test (BET) in pharmaceutical sterile products primarily utilizes:
B
Limulus Amebocyte Lysate (LAL) reagent
✓ Correct
C
Gram staining technique
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Step-by-Step Explanation & Concept Rationale
The LAL test uses an aqueous extract of blood cells (amebocytes) from the horseshoe crab (Limulus polyphemus) to detect minute amounts of bacterial endotoxins (lipopolysaccharides).
What is the primary mechanism of microbial killing in dry heat sterilization using a hot air oven?
B
Oxidative destruction of cellular constituents
✓ Correct
C
Disruption of DNA via alkylation
D
Cell wall lysis via osmotic shock
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Step-by-Step Explanation & Concept Rationale
Dry heat sterilization destroys microorganisms primarily through cellular oxidation and desiccation, whereas moist heat (autoclave) kills via protein coagulation and denaturation.
Which type of water is official in the pharmacopoeia for the compounding and preparation of injectable parenteral solutions?
B
Sterile Water for Injection (SWFI)
✓ Correct
D
Bacteriostatic Water for Irrigation
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Step-by-Step Explanation & Concept Rationale
Water for Injection (WFI) or Sterile Water for Injection (SWFI) is pyrogen-free, sterile purified water obtained by distillation or reverse osmosis meeting strict endotoxin limits (< 0.25 EU/mL).
In rheology, a fluid whose viscosity decreases as shear rate increases without a yield value is called:
A
Dilatant (shear-thickening)
B
Pseudoplastic (shear-thinning)
✓ Correct
💡
Step-by-Step Explanation & Concept Rationale
Pseudoplastic flow (shear-thinning) is exhibited by polymeric solutions where viscosity decreases with increasing shear stress, essential for injectable suspensions and ophthalmic drops.
Which polymer is widely utilized as an enteric coating material because it remains insoluble in gastric acid (pH < 5.5) but dissolves in intestinal juice?
A
Cellulose acetate phthalate (CAP)
✓ Correct
B
Hydroxypropyl methylcellulose (HPMC)
C
Polyethylene glycol (PEG)
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Step-by-Step Explanation & Concept Rationale
Cellulose acetate phthalate (CAP) and Eudragit L/S are polycarboxylic polymers with free acid groups that are un-ionized and insoluble at low stomach pH, but ionize and dissolve in the duodenum.
The electrical potential existing at the shear plane (slipping plane) of a colloidal particle in suspension is known as:
B
Zeta potential
✓ Correct
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Step-by-Step Explanation & Concept Rationale
Zeta potential governs the electrostatic repulsion between adjacent, similarly charged particles. In flocculated suspensions, zeta potential is typically around +/- 20 to 30 mV.
Lyophilization is a pharmaceutical drying process operating on the principle of:
A
Evaporation under atmospheric pressure
B
Sublimation of frozen ice crystals directly into vapor under vacuum
✓ Correct
C
Spray drying with hot circulating air
D
Centrifugal fluidization
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Step-by-Step Explanation & Concept Rationale
Lyophilization (freeze-drying) dries thermolabile products (proteins, antibiotics) by freezing the solution and sublimating ice directly to water vapor below the triple point of water.
According to the USP, what is the maximum permissible percentage weight loss for standard compressed tablets in the friability test?
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Step-by-Step Explanation & Concept Rationale
According to USP/BP pharmacopoeial standards, the maximum acceptable limit for tablet friability is not more than 1.0% of the initial weight, with no broken or cracked tablets.
Which of the following is an example of an oil-soluble antioxidant frequently incorporated into oily pharmaceutical vehicles?
C
Butylated hydroxytoluene (BHT)
✓ Correct
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Step-by-Step Explanation & Concept Rationale
BHT (Butylated hydroxytoluene), BHA, and Tocopherols (Vitamin E) are lipid-soluble antioxidants, while ascorbic acid and sodium metabisulfite are water-soluble antioxidants.
The phenomenon where an emulsion separates into two distinct phases that cannot be re-homogenized upon shaking is called:
C
Cracking (breaking)
✓ Correct
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Step-by-Step Explanation & Concept Rationale
Cracking or breaking is an irreversible destruction of the protective emulsifying film where globules coalesce into separate bulk phases. Creaming, by contrast, is reversible upon shaking.
Which parenteral route of administration offers 100% systemic bioavailability by definition?
C
Intravenous (IV) bolus
✓ Correct
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Step-by-Step Explanation & Concept Rationale
By pharmacologic definition, intravenous (IV) administration places 100% of the active drug dose directly into the systemic circulation, meaning bioavailability F = 1.0 (100%).
Vesicular carrier systems composed of concentric phospholipid bilayers enclosing an aqueous core are designated as:
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Step-by-Step Explanation & Concept Rationale
Liposomes are microscopic vesicular drug delivery carriers formed by concentric phospholipid bilayers capable of entrapping hydrophilic drugs in the core and lipophilic drugs in the bilayer.
Which kinetic order describes the elimination of a constant fraction (percentage) of drug from the body per unit of time?
B
First-order kinetics
✓ Correct
D
Michaelis-Menten saturated kinetics
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Step-by-Step Explanation & Concept Rationale
In first-order kinetics, the rate of drug elimination is directly proportional to plasma concentration; hence, a constant fraction of drug is eliminated per unit time, resulting in a constant half-life.
Which of the following drugs exhibits zero-order elimination kinetics at standard therapeutic or slightly elevated concentrations?
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Step-by-Step Explanation & Concept Rationale
Phenytoin, Ethanol, and Aspirin (high doses) demonstrate capacity-limited (zero-order) elimination kinetics where hepatic enzymes become saturated, and a constant amount is cleared per unit time.
The apparent volume of distribution (Vd) of a drug will be extraordinarily large (> 5 L/kg) if the drug:
A
Is heavily bound to plasma albumin
B
Is highly polar and confined to extracellular water
C
Is lipophilic and extensively sequestered in peripheral tissues and adipose
✓ Correct
D
Has poor oral absorption
💡
Step-by-Step Explanation & Concept Rationale
Drugs like Digoxin, Chloroquine, and Amiodarone have huge Vd (> 500 L in a 70 kg human) because they bind extensively to tissue proteins and lipid reservoirs, leaving very low free concentration in plasma.
Which specific antidote should be administered immediately for acute paracetamol (acetaminophen) overdose to prevent fulminant hepatic necrosis?
B
N-acetylcysteine (NAC)
✓ Correct
💡
Step-by-Step Explanation & Concept Rationale
Paracetamol hepatotoxicity is mediated by the toxic metabolite NAPQI. N-acetylcysteine (NAC) acts as a glutathione precursor and substitute, conjugating and detoxifying NAPQI.
What is the primary mechanism of action of beta-lactam antibiotics (e.g., penicillins, cephalosporins)?
A
Inhibition of 30S ribosomal subunit translation
B
Inhibition of transpeptidase enzymes and bacterial cell wall synthesis
✓ Correct
C
Inhibition of DNA gyrase / topoisomerase II
D
Disruption of bacterial cytoplasmic membrane integrity
💡
Step-by-Step Explanation & Concept Rationale
Beta-lactams bind covalently to Penicillin-Binding Proteins (PBPs / transpeptidases), blocking cross-linking of peptidoglycan chains in bacterial cell walls, triggering osmotic autolysis.