| Term | Definition |
|---|
| Ointments | Semisolid preparations intended for external application to the skin or mucus membranes in which the drug in incorporated into a specific base type. May be medicated or unmedicatied. |
| Oleaginous bases | (Hydrocarbon bases) - Emollient effect, protect escape of moisture, occlusive dressing, difficult to wash off. Only small amount of aqueous solution may be incorporated with some difficulty. EX: Petrolatum and wax |
| Absorbtion bases | Can be used as emollient, although not as occlusive as oleaginous base. Not easily removed by water washing. Can be used to incoporate small volume of aqueous solutions. |
| Water-removable bases | (Water-washable bases) - Oil in water emulsions resembling creams. Easily washed from skin and can be diluted with aqueous solutions. Capable of absorbing serous discharge. |
| Water-soluble bases | Completely water washable (Greaseless). Do not contain oleaginous components. Soften greatly with addition of water. Used to incorporate solid substances. |
| Creams | Similar to emulsions, but often thicker and do not flow when pouring. Semisolid preparations containing one or more medicinal agents dissolved in either a water in oil emulsion or oil in water emulsion or in another type of water-washable base. |
| Vanishing cream | Oil in water emulsions. After applying, the water evaporates, leaving thin residue of steaic acid or other oleaginous component. |
| Continental or dry gum | So called 4:2:1 method. Mix OIL(4 parts) and gum(1 part) first in a container. Grind until size is reduced and uniform, add AQUEOUS phase(2 parts) and continue to grind until uniform. The process can be mechanized and store mechanical energy. |
| English or wet gum | So called 4:2:1 method. Mix WATER(2 parts) and gum(1 part) first in a container. Grind until size is reduced and uniform, add OIL phase(4 parts) and continue to grind until uniform. The process can be mechanized and store mechanical energy. |
| Gels | Liquid or semisolid system of at least 2 components, consisting of a condensed mass enclosing and interpenetrated by liquid. Can be a 1-phase or 2-phase systems. |
| Xerogel | The matrix framework of a gel alone (dried) EX: gelatin sheets, tragacanth ribbons, acacia tears. |
| 1-phase | type of system: Gel consisting of a macromolecules existing as twisted matted strand. Bounded together by stronger types of van del Waals forces to form the crystalline and amorphous region throughout the entire system. No definite boundaries exist between the dispered macromolecules and the liquid. |
| 2-phase | type of system: Gel mass consists of floccules of small particles rather than large molecules. Gel structure is not always stable. Gels may be thixotropic, forming semisolids on standing and becoming liquid on agitation. |
| Organogels | Gels containing organic liquid. Many are "oily" but some are water washable. |
| Hydrogels | Type of gel containing organic or inorganic ingredients that are water soluble or colloidally dispersable. It retain significant amounts of water. Some are water soluble but others are not. |
| Syneresis | Shrinking of gel due to standing for some time. Some of the liquid gets pressed out. |
| Swelling | Enlarging of the gel by taking up liquid causing volume to increase. |
| Imbibition | When gel takes up certain volume of liquid without a measurable increase in volume. |
| Bleeding | Liberation of oil or water from ointment bases, results from a deficient gel structure rather than from a contaction involved in syneresis. |
| Hydration | This method uses materials to form gel naturally upon solvation. |
| Reaction | type of method: Solution of inorganic agents form an insoluble but hydrated precipitates. |
| Surfactants | Reduces interfacial tension. Plays a critical role in the physical stability of bi-phasic systems such as creams. |
| Uses of ointment, creams, and gels | Anti-inflammatories, emollients, lubricants, antibiotics, cleaning, protective barriers, anti-itch. |
| Desired release rate, desirability of topical or percutaneous drug absorption, occlusion of moisture, stability, if water-washable is desired | When selecting an appropriate base, what do you have to consider? |
| Incorporation and fusion | Two type of method for preparation of ointments are. |
| Fusion | type of method: All or those that are not heat labile are melted together and then cooled down with constant stirring until thicken |
| Incorporation | type of method: Components to be included in ointment are mixed into one of the 4 types of ointment bases until a uniform preparation is attained. |
| Solid and liquid | What are the two types of incorporation methods? |
| Opthalmic ointment | Sterility is not required in ointments, creams, and gels with the exception of what? |
| Parabens, phenols, benzoic acid, sorbic acid, quaternary ammonium salt | What are the preservatives used in ointments, creams, and gels? |
| Easier to spread and remove | Why are creams preferred over ointments? |
| They need to be dissolved in either oil or water first | What needs to be done, if additional ingredients are needed to prepare a cream? |
| Particle size, viscosity, density | What are factors affecting stability of creams? |
| Decrease | To make creams more stable, you must increase or decrease particle size? |
| Increase | To make creams more stable, you must increase or decrease viscosity? |
| Decrease | To make creams more stable, you must increase or decrease the density? |
| Heat, extreme cold and humidity | Creams must be kept protected from? |
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