Pharmaceutics I — Study Notes by Source Flashcards

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Powder

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A dry substance composed of ground, pulverized, or finely dispersed solid particles. Powders are mixtures of finely divided drugs and/or chemicals intended for internal or external use in dry form and often require dissolution for absorption.

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Powder Advantages

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Powders are easy to administer and allow flexible dose adjustment, useful in clinical studies. They can be mixed into foods or liquids for patients who cannot swallow and often provide rapid onset since they usually require dissolution rather than disintegration.

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Powder Disadvantages

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Powders may have unpleasant tastes and are difficult to protect from degradation if materials are hygroscopic, deliquescent, or efflorescent. Preparation to a uniform powder can be time-consuming and patients may inaccurately measure bulk powders.

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Hygroscopic

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A hygroscopic substance absorbs moisture from the air but does not dissolve in the absorbed moisture. Examples include certain halide salts and alkaloid salts; such powders should be stored in dry areas or with inert drying agents to reduce moisture uptake.

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Deliquescent

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Deliquescent substances absorb so much moisture from the air that they dissolve partially or completely to form a liquid solution. Common examples include sugar and sodium hydroxide, and they require special handling and packaging to prevent liquefaction.

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Efflorescent

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An efflorescent powder contains water of hydration or crystallization that can be released upon handling or in low humidity, making the powder sticky or pasty. Examples include certain sulfate or acetate salts and such powders may change consistency on manipulation.

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Compressibility

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Compressibility measures a material's ability to reduce its volume under a specified set of conditions. It is a critical property for tablet manufacture as it influences the ability to form a compacted mass under pressure.

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Compactibility

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Compactibility evaluates a powder's ability to be compressed into a coherent tablet of specified strength. It reflects interparticle bonding and is essential for ensuring tablet hardness and integrity.

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Flowability

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Flowability assesses the ability of a powder to flow without sticking to surfaces, which is crucial for consistent filling of capsules and tablet dies. Poor flow can cause weight variation and manufacturing issues.

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Wettability

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Wettability is the tendency of a drug particle to become wet when contacted with a solvent, influencing granulation, dissolution, and dispersibility. Wettability can be enhanced by adding wetting agents such as sodium dodecyl sulfate (SDS).

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Particle Size

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Particle size refers to the dimensions of individual powder particles and strongly influences blend uniformity, dissolution rate, and appearance. Uniform particle sizes blend better, while disparities can lead to segregation and changes in color or texture.

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Micromeritics

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Micromeritics is the science of small particles and their physical properties, including particle size, shape, density, porosity, and surface area. These properties govern behavior in formulation processes such as flow, packing, and dissolution.

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Angle of Repose

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Angle of repose is the steepest angle of a pile of powder at which it remains stable and is an indicator of flowability. Low angles indicate free-flowing powders whereas high angles indicate poor flow.

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True Density

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True density is the density of the solid particles themselves, excluding any voids or interparticle spaces. It is determined by techniques that measure the actual volume occupied by the material's particles.

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Apparent Density

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Apparent density, also called bulk density, is the mass of a powder divided by the bulk volume it occupies, including interparticle voids. It affects container selection and behavior during processing such as tablet compression.

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Porosity

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Porosity is the fraction or percentage of the bulk volume of a powder that is occupied by void spaces between particles. It is calculated from void volume and influences packing, flow, and compaction behavior.

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Bulkiness

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Bulkiness is the reciprocal of apparent density and is typically expressed as volume per unit mass (mL/g). It influences the size of packaging and the apparent volume of a given mass of powder.

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Comminution

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Comminution is the process of reducing the particle size of a solid substance to a finer state of subdivision. It facilitates extraction, increases dissolution rate, enhances absorption, and aids formulation.

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Trituration

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Trituration is the process of rubbing, crushing, or grinding materials together, used both for particle size reduction and intimate mixing of components. It is a common manual method in compounding and small-batch production.

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Levigation

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Levigation reduces particle size and grittiness by grinding a powder with a small amount of an insoluble liquid to form a smooth paste. A levigating agent is the liquid used and must be insoluble in the powder to avoid dissolving the drug.

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Spatulation

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Spatulation is a blending technique using a spatula to mix small quantities of powders and is suitable for sensitive mixtures like eutectics. It is commonly used in compounding when quantities are too small for other mixing methods.

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Eutectic

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A eutectic mixture is a combination of components that melts at a lower temperature than either constituent, potentially forming a liquid when mixed. To avoid problems, ingredients can be dispensed separately, blended with absorbents, or the eutectic can be formed and then adsorbed onto an inert powder.

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Granules

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Granules are agglomerated particles typically ranging from 4 to 12 mesh sieve size, used for improved flow and reduced dust. They are not suitable for potent drugs measured by household utensils and are often used for unstable drugs like reconstitutable antibiotics.

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Effervescent Granules

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Effervescent granules contain acid salts (e.g., citric or tartaric acid) and a bicarbonate that produce carbon dioxide when dissolved, masking unpleasant tastes and producing a palatable, carbonated solution. They should be dispensed in moisture-protective containers and dissolved in water before ingestion.

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Capsule

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A capsule is a unit dose consisting of powder, semisolid, or liquid drug enclosed within an edible hard or soft shell. Capsules provide convenient, tasteless dosing and are available as hard gelatin, soft gelatin, or vegetable capsules.

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Hard Gelatin Capsule

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Hard gelatin capsules consist of two rigid gelatin shells (cap and body) that enclose powdered or granulated drugs; gelatin is soluble in hot water and gastric fluid. They often contain desiccants in packaging because gelatin shells are sensitive to moisture and contain $H_2O$ typically around $13-16\%$.

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Soft Gelatin Capsule

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Soft gelatin capsules are a single-piece, hermetically sealed shell that contain liquids, suspensions, or pasty materials; plasticizers such as glycerin or sorbitol are used to make the shell flexible. They are ideal for encapsulating liquids but can be susceptible to migration of certain solvents and water-sensitive actives.

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Capsule Excipients

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Common capsule excipients include diluents (e.g., lactose), disintegrants (e.g., pregelatinized starch), glidants (e.g., colloidal silicon dioxide), wetting agents, and lubricants. Each excipient serves to improve manufacturability, stability, flow, or drug release characteristics.

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Disintegration Test

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The disintegration test determines whether a dosage unit breaks into fragments and no palpable core remains within a specified time, but it does not measure dissolution. It is a USP compendial requirement for many solid oral dosage forms to ensure timely release.

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Tablet

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A tablet is a solid dosage form containing medicinal substances with or without excipients, usually prepared by compression. Tablets are versatile, economical, and can be manufactured with modified release profiles and various coatings.

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Tablet Advantages

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Tablets offer accurate dosing, low cost, ease of packaging and transport, and clear product identification via imprinting. They are well-suited for large-scale production and can be formulated for diverse release characteristics.

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Tablet Disadvantages

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Tablet absorption can vary between patients and some populations (pediatrics, geriatrics) have difficulty swallowing them. They may be unsuitable for hygroscopic or low-density drugs and can irritate the GI tract or have unpleasant tastes unless coated.

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Film-Coated Tablet

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A film-coated tablet has a thin polymeric film applied to the compressed core to protect against abrasion and sometimes to modify release or mask taste. Aqueous polymers like hydroxypropyl methylcellulose are commonly used to avoid organic solvents.

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Sugar-Coated Tablet

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Sugar-coated tablets have multiple layers of sugar-based syrup applied to the compressed core, providing a barrier to taste and environmental factors but increasing tablet size. The process is lengthy and includes waterproofing, subcoating, smoothing, coloring, and polishing steps.

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Enteric-Coated Tablet

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Enteric-coated tablets have a polymer coat that resists dissolution in acidic gastric pH and dissolves at higher pH in the intestine, providing delayed release. Enteric coatings protect acid-labile drugs and reduce gastric irritation.

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Buccal/Sublingual

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Buccal and sublingual tablets are designed to dissolve in the mouth (cheek or under the tongue) allowing drug absorption through the oral mucosa. They bypass first-pass metabolism and are useful for drugs that are degraded in the GI tract.

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Chewable Tablet

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Chewable tablets are formulated to be chewed thoroughly before swallowing and are often flavored for pediatric or geriatric use. They typically contain non-swellable bases like mannitol and generally do not include disintegrants.

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Tablet Excipients

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Common tablet excipients include diluents (provide bulk), binders (promote particle adhesion), disintegrants (promote breakup), glidants (improve flow), and lubricants (reduce compression friction). Proper selection ensures manufacturability, stability, and desired release.

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Friability

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Friability refers to a tablet's tendency to crumble or generate dust; USP typically accepts up to about 1% weight loss in a friabilator test. Low friability indicates good mechanical integrity during handling and packaging.

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Imprinting

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Imprinting is the requirement to mark oral solid dosage forms with a unique code for product identification, mandated by the FDA for most human drugs. It aids in product tracing, counterfeit prevention, and patient safety, with limited exemptions.