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NHRA Pharmacist Exam study materials
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NHRA Pharmacist Exam practice questions

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Question 1Pharmaceutical Sciences and Drug Chemistry

Which functional group is present in the structure of paracetamol (acetaminophen)?

  1. Ester
  2. Sulfonamide
  3. Carboxylic acid
  4. Amide Correct answer.

Explanation

Paracetamol contains an acetamide group attached to a phenol ring, giving it both analgesic and antipyretic activity. The nitrogen of the amide is bonded to the aromatic ring and to an acetyl group, which defines the amide functional class.

Question 2Pharmaceutical Sciences and Drug Chemistry

Which class of drug acts by inhibiting the enzyme HMG-CoA reductase?

  1. Proton pump inhibitors
  2. Loop diuretics
  3. Beta blockers
  4. Statins Correct answer.

Explanation

Statins such as simvastatin and atorvastatin inhibit HMG-CoA reductase, the rate-limiting enzyme in cholesterol biosynthesis. This reduces hepatic cholesterol synthesis and upregulates LDL receptors, lowering plasma LDL.

Question 3Pharmaceutical Sciences and Drug Chemistry

Which pharmacokinetic parameter is defined as the volume of plasma from which a drug is completely removed per unit time?

  1. Volume of distribution
  2. Clearance Correct answer.
  3. Bioavailability
  4. Half-life

Explanation

Clearance quantifies the volume of plasma cleared of drug per unit time and reflects the efficiency of eliminating organs. It is related to dose and area under the curve by the equation CL = Dose/AUC for intravenous administration.

Question 4Pharmaceutical Sciences and Drug Chemistry

Which analytical technique separates compounds based on differential partitioning between a mobile phase and a stationary phase?

  1. Mass spectrometry
  2. Ultraviolet spectroscopy
  3. Chromatography Correct answer.
  4. Polarimetry

Explanation

Chromatography separates components because they distribute differently between a moving mobile phase and a stationary phase. Compounds with greater affinity for the stationary phase migrate more slowly and elute later.

Question 5Pharmaceutical Sciences and Drug Chemistry

Which excipient is primarily added to a tablet formulation to promote disintegration in the gastrointestinal tract?

  1. Colorant
  2. Binder
  3. Disintegrant Correct answer.
  4. Glidant

Explanation

Disintegrants such as croscarmellose sodium swell or wick water into the tablet, breaking it into granules and particles. This increases surface area and facilitates dissolution and absorption of the active ingredient.

Question 6Pharmaceutical Sciences and Drug Chemistry

Which vitamin deficiency is classically associated with impaired synthesis of clotting factors II, VII, IX, and X?

  1. Vitamin D
  2. Vitamin C
  3. Vitamin K Correct answer.
  4. Vitamin B12

Explanation

Vitamin K is a cofactor for gamma-carboxylation of glutamate residues in clotting factors II, VII, IX, and X. Without carboxylation these factors cannot bind calcium and phospholipid membranes effectively, impairing coagulation.

Question 7Pharmaceutical Sciences and Drug Chemistry

Which type of chemical bond is formed by the sharing of electron pairs between atoms?

  1. Covalent bond Correct answer.
  2. Hydrogen bond
  3. Van der Waals interaction
  4. Ionic bond

Explanation

A covalent bond arises when two atoms share one or more pairs of electrons, typically between nonmetals. The shared electrons allow each atom to attain a stable electron configuration.

Question 8Pharmaceutical Sciences and Drug Chemistry

Which organ is the principal site of first-pass metabolism for orally administered drugs?

  1. Stomach
  2. Lung
  3. Liver Correct answer.
  4. Kidney

Explanation

After absorption from the gut, orally administered drugs pass through the portal vein to the liver before reaching systemic circulation. Hepatic enzymes therefore metabolize a fraction of the dose, reducing oral bioavailability.

Question 9Pharmaceutical Sciences and Drug Chemistry

A drug has a half-life of 6 hours. Approximately what fraction of the steady-state plasma concentration is reached after 24 hours of constant-rate dosing?

  1. About 50%
  2. About 75%
  3. About 94% Correct answer.
  4. About 99%

Explanation

Twenty-four hours corresponds to four half-lives. Steady state is approached exponentially, and after four half-lives approximately 94% of the final steady-state concentration is achieved.

Question 10Pharmaceutical Sciences and Drug Chemistry

Which structural feature most increases the aqueous solubility of a drug molecule?

  1. Greater aromatic ring count
  2. Ionizable groups capable of forming salts Correct answer.
  3. Increased hydrocarbon chain length
  4. Higher halogen content

Explanation

Ionizable acidic or basic groups allow formation of water-soluble salts and increase polarity. This enhances dissolution in aqueous media, which is often exploited in formulation and prodrug design.

Question 11Pharmaceutical Sciences and Drug Chemistry

A patient taking warfarin is prescribed a drug that inhibits CYP2C9. What is the most likely consequence?

  1. Reduced warfarin effect and thrombosis risk
  2. Increased warfarin effect and bleeding risk Correct answer.
  3. Immediate loss of warfarin protein binding
  4. No change because warfarin is renally cleared

Explanation

Warfarin is metabolized primarily by CYP2C9, so inhibiting this enzyme reduces its clearance and raises plasma concentrations. The resulting elevation of INR increases the risk of bleeding, requiring dose adjustment and monitoring.

Question 12Pharmaceutical Sciences and Drug Chemistry

Which reaction type is most commonly used to conjugate drugs and increase their water solubility for renal excretion?

  1. Decarboxylation
  2. Deamination
  3. Glucuronidation Correct answer.
  4. Oxidation

Explanation

Glucuronidation transfers glucuronic acid to nucleophilic groups such as hydroxyl or carboxyl, producing polar conjugates. These conjugates are more water soluble and are readily excreted in bile or urine.

Question 13Pharmaceutical Sciences and Drug Chemistry

Which statement best describes the role of a prodrug in drug design?

  1. It binds irreversibly to its receptor for prolonged action
  2. It is a metabolite that antagonizes the parent drug
  3. It is pharmacologically inactive until converted to the active species in vivo Correct answer.
  4. It is an inactive enantiomer present in a racemic mixture

Explanation

A prodrug is a chemically modified derivative that requires biotransformation to release the active drug. This strategy can improve absorption, taste, stability, or targeting of the active moiety.

Question 14Pharmaceutical Sciences and Drug Chemistry

Which factor most directly determines the rate of drug absorption from an intramuscular injection site?

  1. Hepatic enzyme activity
  2. Renal filtration rate
  3. Plasma protein binding
  4. Blood flow to the injection site Correct answer.

Explanation

Absorption from intramuscular depots depends on diffusion from the tissue into the circulation, which is largely limited by local blood perfusion. Increased blood flow accelerates transfer of drug into systemic circulation.

Question 15Pharmaceutical Sciences and Drug Chemistry

Which of the following best explains why a drug with high lipophilicity may show a large volume of distribution?

  1. Extensive partitioning into tissue lipids and fat Correct answer.
  2. Rapid hepatic first-pass extraction
  3. Rapid renal tubular secretion
  4. High plasma protein binding alone

Explanation

Lipophilic drugs diffuse readily into adipose and other tissues, leaving less drug in plasma and producing a large apparent volume of distribution. This extensive tissue partitioning underlies the relationship Vd = amount in body / plasma concentration.

Question 16Pharmaceutical Sciences and Drug Chemistry

Which spectroscopic method is most appropriate for quantifying a drug that absorbs strongly in the ultraviolet region?

  1. Infrared spectroscopy
  2. Flame photometry
  3. UV-Vis spectrophotometry Correct answer.
  4. Nuclear magnetic resonance

Explanation

UV-Vis spectrophotometry measures absorbance according to the Beer-Lambert law, allowing quantitative determination of chromophores. It is widely used for assay and dissolution testing of drugs with suitable conjugated systems.

Question 17Pharmaceutical Sciences and Drug Chemistry

Which stereochemical property distinguishes enantiomers from each other?

  1. They have different molecular formulas
  2. They have different connectivity of atoms
  3. They rotate plane-polarized light in opposite directions Correct answer.
  4. They differ in melting point when pure

Explanation

Enantiomers are non-superimposable mirror images that rotate plane-polarized light in equal but opposite directions. They share identical connectivity and physical properties in achiral environments but differ in their interaction with chiral systems.

Question 18Pharmaceutical Sciences and Drug Chemistry

A formulation scientist wants to improve the dissolution rate of a poorly water-soluble drug. Which approach is most directly effective?

  1. Increasing tablet hardness
  2. Increasing the binder concentration
  3. Reducing particle size to increase surface area Correct answer.
  4. Adding a hydrophobic lubricant

Explanation

According to the Noyes-Whitney relationship, dissolution rate is proportional to surface area. Reducing particle size increases the exposed surface area, thereby accelerating dissolution of poorly soluble drugs.

Question 19Pharmaceutical Sciences and Drug Chemistry

Which principle underlies the use of a loading dose in clinical pharmacokinetics?

  1. Reducing the fraction of drug bound to plasma proteins
  2. Prolonging the elimination half-life of a drug
  3. Rapidly achieving therapeutic concentrations before steady state is reached Correct answer.
  4. Preventing first-pass metabolism

Explanation

A loading dose rapidly fills the apparent volume of distribution to reach target concentrations without waiting several half-lives. It is calculated from the desired concentration and volume of distribution, then followed by maintenance dosing.

Question 20Pharmaceutical Sciences and Drug Chemistry

Which molecular interaction is primarily responsible for the high selectivity of a drug for its receptor?

  1. Non-specific membrane adsorption
  2. Complete covalent bond formation with the receptor
  3. Random hydrophobic collisions
  4. Complementary three-dimensional fit and noncovalent bonding Correct answer.

Explanation

Selective drug-receptor binding depends on shape complementarity together with hydrogen bonds, ionic interactions, and hydrophobic contacts. These combined interactions allow discrimination among structurally related targets.

Question 21Pharmaceutical Sciences and Drug Chemistry

Which statement correctly describes the effect of adding a competitive antagonist to a system with an agonist?

  1. It irreversibly destroys receptor binding sites
  2. It shifts the agonist dose-response curve to the right without reducing the maximum response Correct answer.
  3. It increases agonist potency at low concentrations
  4. It reduces the maximum agonist response without shifting the curve

Explanation

A competitive antagonist reversibly occupies the orthosteric site, so higher agonist concentrations are needed to achieve the same effect. Because the antagonism can be overcome, the maximum response is preserved while the curve shifts right.

Question 22Pharmaceutical Sciences and Drug Chemistry

Which metabolic pathway is most likely to be saturable at therapeutic doses and lead to nonlinear pharmacokinetics?

  1. Passive diffusion across the intestinal wall
  2. Renal tubular reabsorption of unionized drug
  3. Capacity-limited hepatic oxidation by a single enzyme Correct answer.
  4. Passive glomerular filtration

Explanation

Enzyme-mediated metabolism depends on a finite number of active sites and can become saturated as substrate concentration rises. When this occurs, clearance falls with increasing dose, producing disproportionate changes in plasma concentration.

Question 23Pharmaceutical Sciences and Drug Chemistry

A drug is a weak base with a pKa of 8.4. In urine at pH 6.0, which statement best describes its behavior?

  1. It is equally ionized and unionized at this pH
  2. It is converted to a glucuronide conjugate in the urine
  3. It is largely ionized and its renal reabsorption is reduced Correct answer.
  4. It is largely unionized and rapidly reabsorbed

Explanation

Applying the Henderson-Hasselbalch relationship, a weak base with pKa 8.4 is mostly protonated and ionized at pH 6.0. The charged species is poorly lipid soluble, so tubular reabsorption decreases and urinary excretion increases.

Question 24Pharmaceutical Sciences and Drug Chemistry

Which structural modification of a lead compound is most likely to increase its metabolic stability against oxidative CYP-mediated attack?

  1. Replacing a hydroxyl with a primary amine
  2. Adding a long flexible alkyl chain
  3. Blocking a susceptible aromatic position with fluorine Correct answer.
  4. Introducing an unhindered benzylic methyl group

Explanation

Fluorine at a metabolically labile aromatic position blocks cytochrome P450 hydroxylation through steric and electronic effects. This reduces oxidative clearance and can prolong the half-life of the compound.

Question 25Pharmaceutical Sciences and Drug Chemistry

Which property of a drug most strongly predicts extensive distribution into the central nervous system?

  1. Extensive binding to albumin
  2. High lipophilicity with low plasma protein binding Correct answer.
  3. Strong ionization at physiological pH
  4. High molecular weight with many hydrogen-bond donors

Explanation

Passage across the blood-brain barrier favors small, lipophilic molecules with limited hydrogen bonding and a low unbound fraction in plasma. High lipophilicity and low protein binding increase the free drug available to diffuse into brain tissue.

Question 26Pharmaceutical Sciences and Drug Chemistry

Which analytical technique separates and quantifies the components of a drug mixture based on differential partitioning between a mobile phase and a stationary phase?

  1. Polarimetry
  2. Chromatography Correct answer.
  3. Atomic absorption spectroscopy
  4. Karl Fischer titration

Explanation

Chromatographic methods such as HPLC and GC separate components because each analyte distributes differently between a moving mobile phase and a fixed stationary phase, so they migrate at different rates and are detected separately. This differential migration is the defining principle of chromatographic separation and quantification.

Question 27Pharmaceutical Sciences and Drug Chemistry

A drug is a weak acid with a pKa of 4.5. In the stomach at pH 1.5, which statement best describes its ionization state?

  1. It exists mainly as a positively charged species
  2. Its ionization cannot be predicted from the pKa alone
  3. It is largely unionized, favoring absorption across the gastric mucosa Correct answer.
  4. It is almost entirely ionized and poorly absorbed

Explanation

For a weak acid, the fraction ionized rises as pH exceeds the pKa by the Henderson-Hasselbalch relationship. At pH 1.5, three units below the pKa of 4.5, the acid remains predominantly in its uncharged protonated form, which is more lipid-permeable and better absorbed.

Question 28Pharmaceutical Sciences and Drug Chemistry

Which type of pharmaceutical excipient is incorporated into a tablet formulation primarily to promote disintegration of the compact into smaller particles?

  1. A disintegrant such as croscarmellose sodium Correct answer.
  2. A binder such as povidone
  3. A glidant such as colloidal silicon dioxide
  4. An enteric polymer such as cellulose acetate phthalate

Explanation

Disintegrants act by swelling or wicking to break the tablet matrix apart when it contacts gastrointestinal fluid, increasing surface area for dissolution. Binders, glidants, and enteric polymers serve distinct functions, so only a disintegrant has this primary role.

Question 29Pharmaceutical Sciences and Drug Chemistry

A drug follows first-order elimination with a clearance of 5 L/h and a volume of distribution of 50 L. What is its elimination half-life?

  1. About 0.7 hours
  2. About 6.9 hours Correct answer.
  3. About 10 hours
  4. About 35 hours

Explanation

Half-life equals 0.693 times volume of distribution divided by clearance, so 0.693 x 50 L / 5 L/h gives approximately 6.9 hours. This relationship shows that half-life lengthens with larger distribution volume and shortens with higher clearance.

Question 30Pharmaceutical Sciences and Drug Chemistry

Two batches of the same drug substance differ only in their crystal habit, one being a stable polymorph and the other a metastable polymorph. Which consequence is most consistent with the metastable form?

  1. Identical solubility and dissolution because polymorphs share the same lattice energy
  2. Lower aqueous solubility and slower dissolution, with no tendency to convert
  3. Loss of pharmacological activity because the molecules are chemically different
  4. Higher apparent aqueous solubility and faster dissolution, with a thermodynamic tendency to convert to the stable form Correct answer.

Explanation

Polymorphs share identical chemical structure but differ in crystal lattice packing, so the metastable form has higher free energy, greater apparent solubility, and faster dissolution. Because it is not the thermodynamically favored state, it can convert to the stable polymorph over time, which can alter product performance.

Question 31Pharmaceutics, Dosage Forms and Drug Delivery

Which excipient is added to a tablet formulation primarily to promote disintegration of the tablet in the gastrointestinal tract?

  1. Binder
  2. Glidant
  3. Colorant
  4. Disintegrant Correct answer.

Explanation

A disintegrant swells or wicks water into the tablet matrix so that it breaks apart into granules and particles, increasing the surface area available for dissolution. Binders do the opposite by holding particles together, while glidants improve powder flow.

Question 32Pharmaceutics, Dosage Forms and Drug Delivery

A drug has a hepatic extraction ratio of 0.9 and is given orally. Which formulation strategy is most likely to increase its systemic bioavailability?

  1. Designing a sustained-release formulation that releases drug slowly in the colon
  2. Adding a disintegrant to speed tablet breakup in the stomach
  3. Increasing the dose of the immediate-release tablet
  4. Using a nanoparticle or lipid carrier that delivers drug to the lymphatic circulation Correct answer.

Explanation

Drugs with a high hepatic extraction ratio undergo extensive first-pass metabolism, so bypassing the portal circulation through lymphatic transport can markedly raise systemic exposure. Simply raising the dose or slowing release does not avoid first-pass loss.

Question 33Pharmaceutics, Dosage Forms and Drug Delivery

Which statement correctly describes the mechanism of a transdermal drug delivery system?

  1. Drug is deposited in subcutaneous fat for gradual local release
  2. Drug is delivered into the buccal mucosa to avoid hepatic metabolism
  3. Drug is absorbed directly into the systemic circulation from the lung alveoli
  4. Drug diffuses from a reservoir or matrix through the skin into systemic circulation Correct answer.

Explanation

Transdermal systems deliver drug across intact skin, where the stratum corneum is the rate-limiting barrier, into dermal capillaries and then systemic circulation. Absorption across the skin avoids the gastrointestinal tract and first-pass hepatic metabolism.

Question 34Pharmaceutics, Dosage Forms and Drug Delivery

A suspension for oral use shows rapid sedimentation with a hard, non-redispersible cake. Which formulation change is most appropriate to improve physical stability?

  1. Adding a flocculating agent to produce a loose, easily redispersed structure Correct answer.
  2. Increasing the particle size of the dispersed solid
  3. Removing all wetting agents from the formulation
  4. Reducing the viscosity of the continuous phase

Explanation

Controlled flocculation produces loose aggregates held by weak van der Waals forces, so sediment remains porous and redisperses readily on shaking. Deflocculated systems form hard cakes that are difficult to resuspend.

Question 35Pharmaceutics, Dosage Forms and Drug Delivery

According to the Biopharmaceutics Classification System, a drug is assigned to Class II when it has which combination of properties?

  1. Low solubility and low permeability
  2. Low solubility and high permeability Correct answer.
  3. High solubility and low permeability
  4. High solubility and high permeability

Explanation

BCS Class II covers drugs with low aqueous solubility but high intestinal permeability, so dissolution is the rate-limiting step for absorption. Such compounds are typical candidates for solubility-enhancing formulation approaches.

Question 36Pharmaceutics, Dosage Forms and Drug Delivery

Which factor most directly increases the dissolution rate of a poorly soluble drug according to the Noyes-Whitney relationship?

  1. Increasing the particle size of the solid
  2. Increasing the surface area available for dissolution Correct answer.
  3. Increasing the viscosity of the dissolution medium
  4. Decreasing the agitation of the medium

Explanation

The Noyes-Whitney equation shows dissolution rate proportional to surface area and to the concentration gradient, and inversely related to diffusion path length. Reducing particle size raises surface area and therefore accelerates dissolution.

Question 37Pharmaceutics, Dosage Forms and Drug Delivery

A pharmacist needs to prepare a sterile ophthalmic solution. Which property is most important for the formulation to be acceptable for ocular use?

  1. It must contain a high concentration of preservative to ensure sterility
  2. It must be isotonic or close to isotonic with lacrimal fluid Correct answer.
  3. It must be hypertonic to draw fluid from the cornea
  4. It must be formulated at a pH of 10 to improve stability

Explanation

Ophthalmic solutions should be isotonic or nearly so, since marked tonicity differences cause discomfort and can damage corneal epithelium. They must also be sterile, and preserved only where appropriate, with pH near physiological values for comfort and stability.

Question 38Pharmaceutics, Dosage Forms and Drug Delivery

In a zero-order release system, which statement about drug release is correct?

  1. Release rate is proportional to the amount of drug remaining
  2. Release is governed by a first-order rate constant
  3. Release rate doubles when the remaining dose is halved
  4. A constant amount of drug is released per unit time Correct answer.

Explanation

Zero-order kinetics means the release rate is independent of remaining drug concentration, so a constant quantity is released per unit time. This is the goal of many sustained-release systems designed to maintain stable plasma levels.

Question 39Pharmaceutics, Dosage Forms and Drug Delivery

Which manufacturing issue is most likely when a tablet formulation contains too much fine powder and insufficient binder?

  1. Capping and lamination during compression Correct answer.
  2. Mottled appearance of the tablet surface
  3. Increased tablet hardness
  4. Slow disintegration of the tablet

Explanation

Insufficient binding with a high proportion of fines reduces the compact's tensile strength, so elastic recovery during decompression causes the top or layers to separate as capping or lamination. Adequate binder and granule strength prevent this defect.

Question 40Pharmaceutics, Dosage Forms and Drug Delivery

Which route of administration completely avoids first-pass hepatic metabolism and also avoids absorption across the gastrointestinal mucosa?

  1. Enteric-coated oral tablet
  2. Intravenous injection Correct answer.
  3. Oral immediate-release tablet
  4. Rectal suppository placed in the upper rectum

Explanation

Intravenous administration places drug directly into the systemic circulation, so there is no absorption step and no first-pass hepatic metabolism. Oral and most rectal routes deliver at least some drug to the portal circulation.

Question 41Pharmaceutics, Dosage Forms and Drug Delivery

A lipophilic drug is formulated in a lipid-based self-emulsifying system. What is the primary advantage of this approach?

  1. It eliminates the need for any excipients in the formulation
  2. It converts the drug into a hydrophilic compound
  3. It increases dissolution and absorption of the poorly water-soluble drug Correct answer.
  4. It increases the fraction of drug that is metabolized in the gut wall

Explanation

Lipid self-emulsifying systems form fine emulsions in gastrointestinal fluids, presenting the drug in a solubilized state with a large interfacial area that enhances dissolution and absorption. This is especially useful for BCS Class II compounds.

Question 42Pharmaceutics, Dosage Forms and Drug Delivery

Which statement about the role of a humectant in a topical semisolid is correct?

  1. It attracts and retains water, helping to keep the preparation from drying out Correct answer.
  2. It increases the melting point of the base to make it more rigid
  3. It acts as a strong oxidizing agent
  4. It promotes microbial growth in the product

Explanation

Humectants such as glycerin or propylene glycol absorb moisture from the environment and help retain water in the formulation, preventing drying and improving spreadability. They are not intended to be antimicrobial or oxidizing agents.

Question 43Pharmaceutics, Dosage Forms and Drug Delivery

A patient is prescribed a drug that undergoes extensive first-pass metabolism. Which change would most likely increase systemic exposure without changing the dose?

  1. Switching from an oral solution to an oral tablet
  2. Taking the dose with a large glass of water
  3. Switching from oral to sublingual administration Correct answer.
  4. Taking the dose immediately after a fatty meal

Explanation

Sublingual absorption drains into the systemic venous circulation rather than the portal vein, bypassing hepatic first-pass metabolism and increasing bioavailability. Food and water can alter absorption rate but do not bypass the liver.

Question 44Pharmaceutics, Dosage Forms and Drug Delivery

Which of the following best explains why a drug with a narrow therapeutic index requires careful control of its dosage form performance?

  1. Small differences in plasma concentration can cause toxicity or therapeutic failure Correct answer.
  2. Such drugs are always poorly soluble in water
  3. Such drugs cannot be formulated as tablets
  4. Such drugs are always eliminated unchanged in urine

Explanation

A narrow therapeutic index means the range between effective and toxic concentrations is small, so even modest changes in release or absorption can cause harm. Consistent formulation performance is therefore essential for safety and efficacy.

Question 45Pharmaceutics, Dosage Forms and Drug Delivery

Which excipient is used in a sustained-release matrix tablet to form a hydrophilic gel that controls drug release?

  1. Magnesium stearate
  2. Talc
  3. Sodium starch glycolate
  4. Hydroxypropyl methylcellulose Correct answer.

Explanation

Hydroxypropyl methylcellulose hydrates on contact with water to form a viscous gel layer that slows diffusion of drug out of the matrix. The rate of gel erosion and diffusion determines the release profile.

Question 46Pharmaceutics, Dosage Forms and Drug Delivery

Aqueous solutions of a drug are chemically unstable and degrade rapidly at room temperature. Which formulation approach is most appropriate?

  1. Preparing a more dilute aqueous solution and storing it at room temperature
  2. Storing the aqueous solution in a clear glass container on a shelf
  3. Formulating a dry powder for reconstitution immediately before use Correct answer.
  4. Adding a higher concentration of the drug to the aqueous solution

Explanation

When a drug is unstable in water, removing water by formulating a dry powder for reconstitution limits hydrolysis and improves shelf life. The reconstituted solution is then used within its short stability period.

Question 47Pharmaceutics, Dosage Forms and Drug Delivery

Which statement about a metered-dose inhaler is correct?

  1. A large fraction of the emitted dose is deposited in the oropharynx, and only a small fraction reaches the lungs Correct answer.
  2. Particles larger than 10 micrometers are optimal for alveolar deposition
  3. Most of the emitted dose is deposited in the lungs with a small fraction in the oropharynx
  4. The propellant has no influence on particle size

Explanation

With conventional metered-dose inhalers, a substantial portion of the emitted dose impacts the oropharynx, and only a minority reaches the lower airways. Particle size and inhalation technique strongly influence lung deposition.

Question 48Pharmaceutics, Dosage Forms and Drug Delivery

Which of the following is the primary purpose of coating a tablet with an enteric polymer?

  1. To act as a disintegrant in the stomach
  2. To improve the taste of the tablet
  3. To increase the rate of drug release in the stomach
  4. To prevent release of the drug in the acidic environment of the stomach Correct answer.

Explanation

Enteric polymers are insoluble in gastric acid but dissolve at the higher pH of the intestine, protecting acid-labile drugs or preventing gastric irritation. They delay, rather than accelerate, release in the stomach.

Question 49Pharmaceutics, Dosage Forms and Drug Delivery

A pharmacist is evaluating two generic tablet products against the reference product using in vitro dissolution profiles. Which condition best supports a claim of similarity?

  1. Comparison of tablet weight and hardness only
  2. Similarity factor f2 less than 15 with only 3 units tested
  3. Dissolution tested at a single time point in different media for each product
  4. Similarity factor f2 greater than 50 with at least 12 units tested under the same conditions Correct answer.

Explanation

An f2 value above 50 indicates that the dissolution profiles differ by no more than about 10 percent on average, which supports similarity. The comparison should use at least 12 dosage units tested under identical conditions.

Question 50Pharmaceutics, Dosage Forms and Drug Delivery

Which factor is most likely to increase the rate of drug release from a suppository base?

  1. Using a base with a higher melting point
  2. Reducing the surface area of the suppository
  3. Increasing the viscosity of the molten base
  4. Using a base that melts at body temperature and has lower viscosity Correct answer.

Explanation

A base that melts readily at body temperature and has low viscosity allows the drug to be released and spread over the rectal mucosa more quickly. Higher-melting or more viscous bases retard release.