SP PHAR 6112 Final Exam Chicago State University School of Pharmacy

Explanation:

Correct Answer: (B) 9.1%

Percent w/w (weight/weight) is calculated as the weight of the active ingredient divided by the total weight of the preparation, multiplied by 100. The total weight of the ointment is 10 g (drug) + 100 g (petrolatum) = 110 g total. Therefore: (10 g ÷ 110 g) × 100 = 9.09%, which rounds to 9.1%. This is a critical distinction — the drug is added to 100 g of base, making the total weight 110 g, not 100 g.

Why Other Options are Incorrect:

A. 10.1 — This value has no unit and does not correspond to the correct w/w percentage calculation.

C. 10% — This would be correct only if the total preparation weighed 100 g (i.e., 10 g drug in 90 g base). Since the drug was added to 100 g of base, the total is 110 g, making 10% an incorrect answer.

D. 0.91% — This appears to be a misplaced decimal error. The correct calculation yields 9.1%, not 0.91%.

Explanation:

Correct Answer: (C) Physical adsorption

The adsorption of gas molecules onto the surface of activated charcoal is a classic example of physical adsorption, also known as physisorption. In this process, gas molecules are held onto the surface of the activated charcoal through weak van der Waals forces without any chemical bonding or reaction occurring. Activated charcoal is highly porous with an enormous surface area, making it exceptionally effective at physically trapping and holding gas molecules on its surface. This principle is widely applied in medicine, water filtration, and gas purification.

Why Other Options are Incorrect:

A. Chemical adsorption — Chemical adsorption (chemisorption) involves the formation of strong chemical bonds between the adsorbate and the adsorbent surface. The interaction between gas molecules and activated charcoal does not involve chemical bond formation and is therefore not chemisorption.

B. Neutral adsorption — Neutral adsorption is not a recognized or standard classification in adsorption science. This is not a valid pharmacological or chemical term.

D. Insufficient information — The diagram clearly shows gas molecules being attracted to and held on the surface of activated charcoal, which provides sufficient information to classify this as physical adsorption.

Explanation:

Correct Answer: (C) Swelling agents

Swelling agents are water-soluble polysaccharides such as cellulose derivatives, pectins, and natural gums that absorb significant quantities of water and expand dramatically in volume. This swelling property is fundamental to gel formation as it creates the three-dimensional network structure that gives gels their characteristic viscosity, consistency, and texture. They are a core component of hydrophilic gel formulations in pharmaceutical and cosmetic preparations.

Why Other Options are Incorrect:

A. Structure agents — While structure agents do contribute to the overall framework of a gel, they do not specifically function by absorbing water and swelling. The defining characteristic described — water absorption leading to volume increase — specifically identifies swelling agents.

B. Syneresis agents — Syneresis refers to the contraction of a gel network resulting in the expulsion of liquid from the gel, which is the opposite of the swelling process described in the question.

D. Ageing agents — Ageing in gel technology refers to the slow structural changes that occur over time in a gel network, leading to changes in consistency and stability. This does not describe the mechanism of water absorption and volumetric expansion outlined in the question.

Explanation:

Correct Answer: (B) The therapeutic range

The therapeutic range, also called the therapeutic window, refers to the range of plasma drug concentrations that produces the desired therapeutic effect without causing toxicity. It is bounded at the lower end by the minimum effective concentration (MEC), below which the drug has no therapeutic effect, and at the upper end by the minimum toxic concentration (MTC), above which adverse or toxic effects occur. Maintaining drug levels within this range is the fundamental goal of pharmacokinetic dosing.

Why Other Options are Incorrect:

A. The area under the curve — The area under the curve (AUC) is a pharmacokinetic measurement that represents the total drug exposure over time. It reflects bioavailability but does not specifically describe the plasma concentration range between efficacy and safety thresholds.

C. The minimum effective concentration — This refers only to the lowest plasma concentration at which the drug produces a therapeutic effect. It is the lower boundary of the therapeutic range, not the range itself.

D. The maximum effective concentration — This is not a standard pharmacokinetic term. The upper boundary of the therapeutic range is defined by the minimum toxic concentration, not a maximum effective concentration.

Explanation:

Correct Answer: (B) Tablets

Tablets are by far the most commonly dispensed dosage form in the United States. They are preferred in pharmaceutical practice due to their ease of manufacturing, precise dose accuracy, long shelf life, cost-effectiveness, patient convenience, and ease of swallowing. The majority of oral prescription and over-the-counter medications are formulated as tablets, making them the dominant dosage form dispensed in retail, hospital, and mail-order pharmacies across the United States.

Why Other Options are Incorrect:

A. Transdermal patch — While transdermal patches are an important drug delivery system for certain medications such as fentanyl, nitroglycerin, and nicotine, they represent a small fraction of total dispensed prescriptions due to their limited applicability to only specific drugs with suitable physicochemical properties.

C. Capsules — Capsules are the second most commonly dispensed solid oral dosage form after tablets. While widely used, they are less prevalent than tablets in overall prescription volume due to higher manufacturing costs and fewer available formulations.

D. Syrups — Syrups are liquid oral formulations primarily used for pediatric patients or individuals who cannot swallow solid dosage forms. They represent a significantly smaller proportion of dispensed prescriptions compared to tablets.

Explanation:

Correct Answer: (A) Oleaginous

Oleaginous (oil-based) formulations such as ointments made with petrolatum or mineral oil are the most effective choice for hydrating dry skin. They work by forming an occlusive barrier on the skin surface that prevents transepidermal water loss (TEWL), trapping moisture within the skin and allowing it to rehydrate. Oleaginous bases have the greatest moisturizing and emollient effect of all topical formulation types, making them the preferred choice for dry skin hydration.

Why Other Options are Incorrect:

B. Foams — Foam formulations are lightweight, spread easily, and are preferred for hairy areas or large body surfaces. They do not provide the occlusive, moisturizing barrier needed to hydrate significantly dry skin.

C. Aerosols — Aerosol formulations deliver drug as a fine spray and evaporate quickly after application. The rapid evaporation actually contributes to skin drying rather than hydration, making them unsuitable for this purpose.

D. Elixirs — Elixirs are oral liquid formulations containing alcohol and water used for systemic drug delivery. They are not topical preparations and are entirely inappropriate for skin hydration.

Explanation:

Correct Answer: (C) Pinocytosis

Pinocytosis, also known as "cell drinking," is the process by which cells engulf extracellular fluid along with dissolved solutes, large protein molecules, oils, and fat-soluble vitamins by forming small vesicles at the cell membrane. This is a form of endocytosis that allows the cell to absorb substances that are too large to pass through membrane channels or transporters. It is particularly important in intestinal epithelial cells for the absorption of fat-soluble vitamins (A, D, E, K) and lipid molecules.

Why Other Options are Incorrect:

A. Phagocytosis — Phagocytosis means "cell eating" and refers to the engulfment of large solid particles such as bacteria, dead cells, and cellular debris. It is primarily carried out by immune cells such as macrophages and neutrophils and is not responsible for absorbing fluid solutes, oils, or vitamins.

B. Physiocytosis — This is not a recognized or established biological term or cellular mechanism. It does not describe any known process of cellular uptake or absorption.

D. Transcytosis — Transcytosis involves the transport of substances across the interior of a cell, where a molecule is taken in on one side of the cell, transported through the cell in a vesicle, and released on the other side. While it plays a role in transporting certain proteins across epithelial barriers, it is not the primary mechanism responsible for the cellular uptake of fluid solutes, oils, and fat-soluble vitamins.

Explanation:

Correct Answer: (B) Diagnostic gels

Aquasonic 100 is an ultrasound transmission gel specifically formulated to serve as an acoustic coupling medium between the ultrasound transducer and the skin surface. It eliminates air gaps that would block or distort ultrasound waves, ensuring optimal sound wave transmission for medical imaging and therapeutic ultrasound procedures. Because its primary function is to facilitate a medical diagnostic and therapeutic procedure rather than to deliver an active drug or lubricate a surface, it is classified as a diagnostic gel.

Why Other Options are Incorrect:

A. Lubricating gels — Lubricating gels such as Astroglide are designed to reduce friction between surfaces for personal or procedural use. While Aquasonic does reduce friction between the transducer and skin, its primary and defining function is ultrasound transmission, not lubrication.

C. Medicated gels — Medicated gels contain active pharmacological ingredients intended to produce a therapeutic drug effect. Aquasonic 100 contains no active drug ingredient and does not exert any pharmacological effect on the body.

D. Miscellaneous gels — Miscellaneous is a non-specific catch-all category. Aquasonic has a well-defined, specific clinical function as an ultrasound coupling medium, which clearly places it in the diagnostic gels category rather than a miscellaneous one.

Explanation:

Correct Answer: (A) Iontophoresis

Iontophoresis is a physical skin penetration enhancement technique that uses a low-level direct electrical current to drive ionized (charged) drug molecules through the skin and into underlying tissues. The electrical current repels charged drug molecules from an electrode of the same charge, forcing them through the skin barrier. It is the definitive electrical enhancement method for transdermal drug delivery and is used clinically for delivering drugs such as lidocaine, dexamethasone, and fentanyl.

Why Other Options are Incorrect:

B. Microporation — Microporation creates microscopic channels or pores in the skin using physical methods such as microneedles, laser energy, or radiofrequency. It is a mechanical or thermal enhancement technique, not an electrical one.

C. Sonophoresis — Sonophoresis (also called phonophoresis) uses ultrasound waves to enhance skin penetration. It is an acoustic/mechanical enhancement technique, not an electrical one.

D. Phonophoresis — Phonophoresis is another name for sonophoresis, which uses ultrasound pulses to disrupt the stratum corneum and enhance drug penetration. Like sonophoresis, it is an ultrasound-based technique, not an electrical enhancement procedure.