331 Semisolids

Semisolids include [blank_start]pastes[blank_end], [blank_start]ointments[blank_end], and [blank_start]creams[blank_end]

Semisolids: A system that is not [blank_start]pourable[blank_end] and does not [blank_start]flow[blank_end] under low shear stress at [blank_start]room temperature[blank_end]

Semisolid dosage forms include ointments, creams, pastes, [blank_start]gels[blank_end], and [blank_start]collodions[blank_end].

Semisolid dosage forms can have topical, [blank_start]ocular[blank_end], [blank_start]nasal[blank_end], [blank_start]vaginal[blank_end], and [blank_start]rectal[blank_end] applications

Ointment: Semisolid preparations, incorporated into a specific [blank_start]hydrocarbon base[blank_end], intended for external application to the skin or mucous membranes. They usually contain < [blank_start]20[blank_end] % water and > [blank_start]50[blank_end] % hydrocarbons

Creams: Semisolid dosage forms that possess a relatively [blank_start]fluid[blank_end] consistency formulated as either water‐in‐oil or oil‐in‐water emulsions. Creams usually contain > [blank_start]20[blank_end] % water and volatiles and < [blank_start]50[blank_end] % hydrocarbons, [blank_start]waxes[blank_end] or [blank_start]polyols[blank_end] as the vehicle.

Gels: Semisolid systems consisting of either suspensions made up of small inorganic particles (e.g. [blank_start]Aluminum Hydroxide Gel[blank_end]) or large organic molecules (e.g. [blank_start]Carbomer[blank_end] or natural gums like Tragacanth) interpenetrated by a liquid.

Pastes: A semisolid dosage form containing a large proportion ([blank_start]20[blank_end]‐50 %) of solids [blank_start]finely[blank_end] dispersed in a [blank_start]fatty vehicle[blank_end].

Collodions: A thick solution composed of [blank_start]pyroxylin[blank_end] dissolved in a mixture of [blank_start]alcohol[blank_end] and [blank_start]ether[blank_end].

[blank_start]Emollient[blank_end]: An agent that softens the skin or soothes irritation in skin or mucous membranes.

[blank_start]Protective[blank_end]: A substance that protects injured or exposed skin surfaces from harmful or annoying stimuli allowing rejuvenation of the skin.

[blank_start]Occlusive[blank_end]: Retention of water in the skin by forming a hydrophobic a barrier that prevents moisture evaporation.

[blank_start]Humectant[blank_end]: A substance that causes water to be retained because of its hygroscopic properties.

Desired properties for semisolid bases include chemical and physical [blank_start]stability[blank_end], nonreactive and [blank_start]compatibility[blank_end], free of objectionable [blank_start]odor[blank_end], nontoxic, nonsensitizing, and nonirritating, and aesthetically appealing.

According to the USP, there are 4 general classes of bases: - [blank_start]Hydrocarbon[blank_end] - [blank_start]Absorption[blank_end] (anhydrous, w/o) - [blank_start]Water removable[blank_end] (o/w) - [blank_start]Water soluble[blank_end]

[blank_start]Anhydrous absorption bases[blank_end]: Hydrocarbon bases that contain emulsifier(s) that form water‐in‐oil emulsions when water or an aqueous solution is added. Absorbs the highest amount of water.

[blank_start]W/O emulsions[blank_end]: Contain water (amount depends on the base). Add something with high HLP value.

[blank_start]Levigation[blank_end]: The process of reducing particle size of a solid by triturating or spatulating with a small amount of a viscous liquid or melted base in which the solid is not soluble.

Levigating agents that are somewhat viscous liquids with low surface tension that don't contain water include [blank_start]glycerin[blank_end], [blank_start]propylene glycol[blank_end], and [blank_start]mineral oil[blank_end].

General rule for choosing a levigating agent: Choose something that is chemically similar to the base. - [blank_start]Mineral oil[blank_end] for oily bases - [blank_start]Glycerin[blank_end] for water-removable bases

Some active ingredients require special levigating agent: - [blank_start]Tween80[blank_end] for Coal Tar - [blank_start]Castor Oil[blank_end] for Balsam of Peru - [blank_start]Glycerin[blank_end] or Fixed Oils for Ichthammol

Some ingredients that have compatibility problems: - Tween 80 is not compatible with [blank_start]w/o emulsion[blank_end] bases - Castor Oil is not compatible with significant amounts of [blank_start]Mineral Oil[blank_end]

Which of the following are water miscible solvents?

Hydrocarbon bases are miscible with most oils but reduces the [blank_start]viscosity[blank_end].

[blank_start]Anhydrous absorption bases[blank_end]: - Large amounts of water, and lesser amount of alcohol (dissolves the emulsifier) - Miscible with most oils, but reduces the viscosity

[blank_start]W/O emulsion[blank_end] bases: - Variable amounts of water and alcoholic solutions - Easily accept most oils, but viscosity may decrease

[blank_start]Water removable[blank_end] bases: - Limited amounts of water or alcohol, eventually thin out to a lotion - Some amounts of oil, larger amounts by adding polysorbate 80

[blank_start]Water soluble[blank_end] bases: - Very limited amount of water or alcohol without loss of viscosity - Some oil, with prior levigation with glycerin or propylene glycol

[blank_start]Pulverization[blank_end] by [blank_start]intervention[blank_end]: The material is dissolved in a solvent, The solvent is allowed to evaporate to produce a thin film Other ingredients are spread on top of this thin film

[blank_start]Fusion method[blank_end]: All or some chemicals in the ointment are combined by being melted together and cooled.

For pastes, we don't use a [blank_start]levigating agent[blank_end], we use a part of the base.

The issue with pastes and their physical stability is that it could result in [blank_start]phase separation[blank_end]

[blank_start]Microbial content[blank_end] - Are not required to be sterile (except ophthalmic preparations), but there is a microbial count limit

To minimize number of micro-organisms: - Environmental control - [blank_start]Adding preservatives[blank_end] - [blank_start]GMP[blank_end] - Finished product control

Special pharmacopeial standards: - [blank_start]Viscosity[blank_end] - In-vitro release - [blank_start]Content uniformity[blank_end]

[blank_start]Minimum Fill[blank_end]: Determination of net weight or volume

[blank_start]Packaging[blank_end]: In largemouth jars or metal or plastic tubes

[blank_start]Storage[blank_end]: Well closed container and cool place. - Keeps base intact