Solid Dosage Forms I: Powders and Granules

Vocabulary flashcards covering solid dosage forms, including powders, granules, particle size analysis, micromeritics, geometric dilution, eutectic mixtures, and flowability.

Powder Dosage Form

Finely divided drugs and/or chemicals mixture in dry form intended to be used internally (oral powders) or externally (topical powders).

Sieve Screen Size

Indicates the number of openings in the mesh screen per inch; for example, a #40 sieve has 40 openings per inch.

Divided Powders

Single doses of powder drug mixtures individually enclosed in paper, cellophane, or metallic foil wrappers or packets.

Bulk Powders

Powders intended to be administered in safe, patient-measured dosage quantities, such as dusting powders, douche powders, laxatives, and antacids.

$$d_{90}$$

The smallest sieve opening through which $90\%$ or more of the material passes.

$$d_{50}$$

The smallest sieve opening through which $50\%$ or more of the material passes.

$$d_{10}$$

The smallest sieve opening through which $10\%$ or more of the material passes.

Comminution

The process of reducing the particle size of a solid substance to a finer state or subdivision to increase its surface area.

Trituration

A particle size reduction process of grinding a drug in a pestle and mortar.

Levigation

A comminution method used in preparing smooth ointments by forming a paste with a small amount of liquid levigating agent and triturating to prevent grittiness.

Milling

A mechanical process of reducing the particle size of solids before mixing with other components or incorporation into a final product.

Micromeritics

The science and technology of small particles, including the study of particle size, distribution, shape, angle of repose, porosity, and density.

Andreasen Pipet

A special cylindrical container used in sedimentation analysis where powder is dispersed in a non-solvent and samples are withdrawn over time to calculate particle size.

Geometric Dilution Method

A sequential, stepwise mixing technique used to ensure uniform distribution of a small amount of potent active ingredient throughout a larger amount of excipient.

Eutectic Mixture

A physical combination of solid components that, when mixed in specific proportions, melt at a lower temperature than any of the individual components.

EMLA Cream Eutectic Mixture

A combination of Lidocaine and Prilocaine that forms a eutectic mixture melting at $\sim 18\,^\circ\text{C}$ used for topical anesthesia.

Granules

Agglomerates of smaller particles prepared by moistening or compressing powder mass; they are irregular in shape, flow better, and are generally more stable than powders.

Effervescent Granules

Coarse to very coarse powders containing a medicinal agent in a dry mixture of sodium bicarbonate, citric acid, and tartaric acid that release carbon dioxide in water.

Angle of Repose

A method to estimate powder flowability calculated via $\tan(\theta) = \frac{h}{r}$, where $h$ is height and $r$ is radius of the powder cone; lower angles indicate better flow.

Rhombohedral Packing

The closest packing arrangement for uniform spherical particles in a powder bed, resulting in a porosity of $26\%$.

Cubic Packing

The most open or loosest packing arrangement for uniform spherical particles in a powder bed, resulting in a porosity of $48\%$.

True Density

The density of the material itself, exclusive of voids and intraparticle pores.

Granule Density

Density determined by mercury displacement, which does not penetrate into pores smaller than $10\,\mu\text{m}$.

Bulk Density

Density determined from the total bulk volume and weight of a dry powder in a graduated cylinder.

Bulkiness

The reciprocal of apparent density ($B = \frac{1}{\rho_a}$).

Laser Diffraction Method

The most sensitive measurement technique for determining particle size distribution (PSD).