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127 Cards in this Set

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Define "Emulsion."
An emulsion is a thermodynamically-unstable, two-phase system consisting of at least two immiscible liquids - one of which is dispersed in the form of small droplets throughout the other - and an emulsifying agent.
What is the dispersed liquid in an emulsion called?
The dispersed liquid of an emulsion is called internal or discontinuous phase.
What is the dispersion medium in an emulsion called?
The dispersion medium of an emulsion is called the external or continuous phase.
Define "O/W"
Emulsions where oils, petroleum hydrocarbons, and/or waxes are the dispersed phase, while water or an aqueous solution is the continuous phase.

**oil-in-water emulsion**
What guidelines determine if an emulsion is O/W?
An emulsion is of the O/W type if the aqueous phase constitutes > 45% of the total weight and a more hydrophilic emulsifier is used.
Define "W/O"
Emulsions where water or aqueous solutions are dispersed in an oleaginous medium.

**water-in-oil emulsion**
What guidelines determine if an emulsion is W/O?
An emulsion is of the W/O type if the aqueous phase constitutes < 45% of the total weight and a more lipophilic emulsifier is used.
What three factors determine the type of emulsion?
1) Type of Emulsifier, 2) Phase Ratio (relative amounts of oil and water), and 3) Order of Mixing.
What are four desired properties of a liquid emulsion for oral or topical use?
1) Fine droplets, 2) Slow aggregation of the droplets, 3) Slow creaming of the product, and 4) Ease of re-dispersion when shaken.
What is the preferred emulsion type for oral use?
O/W, b/c an oily feel in the mouth is objectionable
What is the most common emulsion type?
Oil-in-Water (O/W)
What emulsion type do you use externally when ease of removal or a non-greasy feeling is desired?
Oil-in-Water (O/W)
What emulsion type is used externally when emollient, lubricating, or protective properties are desired?
Water-in-Oil (W/O)
What is the primary disadvantage of Oral Emulsions?
They are usually less acceptable to patients than solutions or suspensions because of the oily feel in the mouth.
Under what two circumstances is an oral emulsion formulated?
1) When it is necessary to make a liquid product of an oil, and 2) When the solubility or bioavailability characteristics of a drug make this delivery system clearly superior.
What are three examples of Parenteral Emulsions?
1) Oil-in-Water, sustained-release depot injections (given IM); 2) Water-in-Oil emulsions of allergenic extractions (given SC); and 3) Lipid emulsions containing a physical mixture of medium and long chain triglycerides (used for nutrition in critically ill patients)
What is the main benefit of topical emulsions?
When the oils are emulsified, they feel less greasy and are more aesthetically appealing to patients.
What two functions do the oil of a topical emulsion serve?
1) Emollience (soothing of the skin) and 2) Protection of the skin.
Define "Emulsifying Agents."
Emulsifying agents are surfactants that concentrate at the interface of the two immiscible phases and prevent coalesence of the droplets.
Aside from concentrating at the interface of two immiscible phases, preventing coalescense, what other benefits do some emulsifying agents provide?
Some agents also increase the viscosity of the system, slowing aggregation of the droplets and decreasing the rate of creaming.
List some Cationic Synthetic Emulsifying Agents
Benzalkonium Chlorides (there are several) & Benzethonium Chloride
What are the three types of Anionic Synthetic Emulsifying Agents?
1) Alkali Soaps (Na+ or K+ oleate), 2) Amine Soaps (triethanoloamine sterate), and 3) Detergents (sodium lauryl sulfate, sodium dioctyl sulfosuccinate, sodium docusate).
What are three types of Non-Ionic Synthetic Emulsifying Agents?
1) Spans, 2) Tweens, & 3) Glyceryl Esters
What are three types of Natural Emulsifying Agents?
1) Vegetable Derivatives (acacia, agar, pectin, lecithin), 2) Animal Derivatives (gelatin, lanolin, cholesterol), and 3) Semi-Synthetic (methylcellulose, carboxymethylcellulose)
Why is Acacia unique among the natural polymer emulsifiers?
Acacia is unique in its ability to form emulsions using only a Wedgewood mortar and pestle, which makes it a useful ingredient for the extemporaneous compounding of emulsions.
The acacia emulsification process require the formation of what?
The acacia emulsification process requires the formation of a primary emulsion.
What is a "Primary Emulsion?"
A primary emulsion is the initial emulsion provided by a prerscribed ratio of ingredients. By optimizing the viscosity and consistency, this ingredient ratio maximizes the shearing force, thus facilitating emulsion formation.
What is the ingredient ratio for primary acacia emulsions of fixed oils (vegetable and mineral)?
(o : w : a) 4:2:1
What is the ingredient ratio for primary acacia emulsions of volatile oils?
(o : w : a) 3:2:1
What is the ingredient ratio for primary acacia emulsions of essential oils?
(o : w : a) 2:2:1
Are preservatives required for acacia emulsions?
Yes! Acacia emulsions are susceptible to microbial growth, especially mold.
What is the pH range of a normal acacia emulsion? What type of preservatives are effective in that range? [Provide two specific examples.]
The pH range of a normal acacia emulsion is 4.5 to 5. Preservatives that require a slightly acidic pH, such as benzoic acid or sorbic acid, are effective in this pH range.
What are the most common non-ionic emulsifying agents for liquid emulsions?
The most common non-ionic emulsifying agents are combinations of Polysorbates (Tweens) with Sorbitan Esters (Spans).
"Span-Tween surfactants"
What is the typical amount of emulsifier needed for liquid emulsions?
5%
What does a high HLB number mean?
A high HLB number means the compound has more hydrophilic character.
What does a low HLB number mean?
A low HLB number means the compound has more lipophilic character.
Which emulsifier typically has a low HLB number? Which phase, oil or water, do they cause to predominate and what type of emulsions do they form?
The oil soluble Spans typically have a low HLB number. They cause the oil phase to predominate and form w/o emulsions.
Which emulsifier typically has a high HLB number? Which phase, oil or water, do they cause to predominate and what type of emulsions do they form?
The water soluble Tweens typically have a high HLB number. They cause the water phase to predominate and form an o/w emulsion.
What HLB number range of Spans are considered lipophilic and form water-in-oil emulsions?
1.8 to 8.6
What HLB number range of Tweens are considered hydrophilic and favor oil-in-water emulsions?
9.6 to 16.7
How do you measure Spans and Tweens?
Spans and Tweens are measured by weight.
What physical form do Spans and Tweens have at room temperature?
At room temp some Spans and Tweens are are solids, while others are thick liquids.
Do all emulsions require a preservative?
Yes - The aqueous phase is favorable to the growth of microorganisms.
What are the two predominant manifestations emulsion instability?
Creaming & Coalescence
Define "Creaming."
Creaming is the migration of droplets of the internal phase to the top or bottom of the emulsion. [The direction depends on the relative densities of the internal and external phases.]
Define "Coalescence."
Coalescence is the merging of small droplets into larger droplets, eventually leading to the complete separation of phases so that they cannot be re-emulsified by simple shaking. In other words, coalescence leads to "cracking."
What is the alternate term for "Irreversible Coalescence"?
"Cracking"
Describe proper storage and beyond-use dating for emulsions for internal use and for external use.
Internal Use Preparations should be refrigerated [BUD of up to 14 days if all ingredients are chemically stable]. External Use Preparations should be stored at Room Temp. [Usual BUD max for chemically stable external preparations is 1 month].
What is a cream?
A cream is a semisolid dosage form containing one or more drug substances dissolved or dispersed in a suitable base.
What is an ointment?
An ointment is a semisolid preparation intended for external application to the skin or mucous membranes.
What are the 4 classes of ointment bases?
1) Hydrocarbon, 2) Absorption, 3) Water-removable, & 4) Water-soluble
What are five desired characteristics of hydrocarbon or oleaginous bases?
1) Inexpensive, 2) Non-reactive, 3) Non-irritating, 4) Good emollient, protective, and occlusive properties, and 5) Not washed off easily, so they hold incorporated medications in contact with the skin.
What are three undesirable properties of hydrocarbon or oleaginous bases?
1) Have poor patient acceptance because of their greasy nature, 2) Are not removed easily with washing when this is desired (note: they may be removed with Mineral Oil, and 3) Cannot absorb water and can only absorb very limited amounts of alcoholic solutions, so most liquid ingredients are difficult to incorporate and skin secretions do not readily dissipate.
What are three uses of ointments, creams, gels, and pastes?
1) To protect skin or mucous membrane from chemical or physical irritants in the environment and to permit rejuvenation of the tissue, 2) To provide hydration of the skin or an emollient effect, and 3) To provide a vehicle for applying a medication either for local or systemic effect.
What are the two absorption base subgroups?
1) Anhydrous absorption bases & 2) Water-in-oil emulsions
What are four absorption base advantages?
1) Moderately good protective, occlusive, and emollient properties, 2) Not washed off easily, so they hold incorporated medications in contact with the skin, 3) Capable of absorbing liquids, and 4) Some lanolin-types have compositions somewhat like the sebaceous secretions of the skin and are thought to have superior emollient properties.
What are six adsorption base disadvantages?
1) Some have poor patient acceptance, b/c of greasy texture (anhydrous bases), or stickiness or unpleasant odor (some lanolin-type bases), 2) Not easily removed by washing (may be removed with mineral oil) 3) Those bases containing wool wax or wool wax alcohols may be sensitizing, 4) Those with soap-type emulsifiers (e.g., Cold Cream, Rose Water Ointment) can have compatibility problems, 5) Those that contain water may have stability problems with ingredients that are sensitive to hydrolysis, and 6) Those containing water are subject to microbial growth (manufactured bases of this type contain preservatives).
What is the term “cream” reserved for?
Water-removable, oil-in-water emulsion bases or microcrystalline dispersions of long chain fatty acids or alcohols in water.
What are water-removable bases?
Water-removable bases are oil-in-water emulsions or creams.
What are four advantages of water-removable bases?
1) Nongreasy and therefore aesthetically pleasing, 2) Can be removed from the skin by washing, 3) Can absorb some water or alcohol (if the amount of liquid added reaches a critical amount, the base will thin out to a lotion), 4) Will allow the dissipation of fluids from injured skin.
What are five disadvantages of water-removable bases?
1) Less protective, less emollient, and less occlusive than hydrocarbon or absorption bases, 2) Those with soap-type emulsifiers can have compatibility problems, 3) Those that contain water may have stability problems with ingredients that are sensitive to hydrolysis, 4) Those containing water are subject to microbial growth (manufactured bases of this type contain preservatives), and 5) Because water is the external phase, these products "dry out" if exposed to air [Humectants may be added to retard dehydration].
What are seven characteristics of water-soluble bases (gels)?
1) Are soluble in water so are easily removed by washing, 2) Leave no oil residue, 3) Can absorb some water or alcohol (as the amount of liquid added increases, the base begins to thin out and eventually dissolves), 4) Irritating, especially on denuded or abraded skin or mucous membranes, 5) Have little to no emollient properties, 6) PEG-type bases may have compatibility problems with incorporated drugs that are subject to oxidation, and 7) Those that contain water may have the compatibility and stability problems associated with water.
What amount of excess product should you make in order to make up for that which is lost during compounding?
10% or 3 grams
List three reasons why ointment slab preferred to pads?
1) Liquids soak into the parchment paper of ointment pads, and excess weight can be lost, 2) Very sticky or thick ointments are often more easily made on a slab, and 3) Loss is usually less when an ointment is compounded on an ointment slab than on a pad.
When should you use a large metal spatula?
Large metal spatulas are used for levigation, spatulation, and incorporation of solid and liquid ingredients.
When should you use a small metal spatula?
The smaller metal spatulas are useful for removing product from the large spatula and for transferring product from the ointment slab or pad to the ointment jar.
When should you use a black rubber or plastic spatula?
Black rubber or plastic spatulas are special purpose spatulas that are used when an ingredient (e.g., iodine) reacts with a metal spatula.
List four situations when a levigating agent should not be used?
1) The solid being incorporated has a very fine particle size, 2) he quantity of solid to incorporate is small, 3) The ointment base is soft, and 4) The final product is to be a stiff ointment or paste.
What technique should you use to mix a smaller quantity of drug into an ointment?
Geometric Dilution
On what bases are levigating agents usually chosen?
Levigating agents are usually chosen to be chemically similar to the ointment base (assuming no compatibility problems with other ingredients).
When mineral oil is used as a levigating agent, it is usually for what two ointment bases?
Mineral oil is typically used for 1) hydrocarbon bases and 2) absorption bases, such as those of water-in-oil.
When glycerin is used as a levigating agent, it is usually for what two ointment bases?
1) Water-Removable Bases & 2) Water-Soluble Bases
What are four characteristics of coal tar?
1) Antipruritic (preventing or relieving itching), 2) Antipsoriatic (relieving the symptoms of psoriasis), 3) Antiseborrheic (relieving seborrhea, i.e. the excessive secretion of sebum), and 4) Keratolytic (an agent that dissolves or breaks down the outer layer of skin (the keratins)).
How is cold tar obtained?
Coal Tar is the tar obtained as a by-product during the destructive distillation of bituminous coal at temperatures in the range of 900 to 1100 C.
What is in a coal tar topical solution?
Coal Tar Topical Solution (LCD= Liquid Carbonis Detergens): Coal Tar: 200 g, Polysorbate 80: 50 g; Alcohol, qs 1000 mL.
What are four factors that determine the amount of levigating agent needed?
1) The quantity and properties of the solids to be incorporated, 2) The levigating agent selected, 3) The properties of the ointment base, and 4) The desired spreading consistency of the ointment [The amount of levigating agents used in official products can serve as a guide, but these vary considerably].
If the prescription doesn’t say how much levigating agent to include how much should be included?
Include the minimum amount of levigating agent necessary to lubricate the powders.
What concerning the levigating agent do you need to document and where?
The name of the levigating agent and the quantity used should be noted on the face of the prescription order or the compounding record.
Under what circumstance would you use dissolution in the preparation of an ointment?
To dissolve a solid ingredient in a solvent or oil to allow for better mixing when it is subsequently incorporated into the ointment.
What are the two types of solvents? [Provide examples of each].
1) Water-Miscible Solvents (Water, Alcohol, Isopropyl Alcohol, Glycerin, Propylene glycol, & Polyethylene Glycol 400), & 2) Lipophilic solvents (Mineral Oil and the various fixed oils, including Castor Oil, Cottonseed Oil, Olive Oil, & Corn Oil)
What is the capacity of hydrocarbon bases to absorb liquids?
Hydrocarbon bases do not absorb any water and only very limited amounts of alcoholic solutions.
What is the capacity of absorption bases to absorb liquids?
1) Anhydrous absorption bases can absorb large quantities of aqueous solutions and lesser amounts of alcoholic solutions, & 2) Water-in-oil emulsion bases accept varied amounts of water and alcoholic solutions.
What is the capacity of water-removable bases to absorb liquids?
Water-removable, oil-in-water emulsion bases accept water or water-miscible liquids in their external phase, but eventually thin out to a fluid lotion with the addition of significant amounts of these liquids.
What is the capacity of water-soluble bases to absorb liquids?
As their name indicates, water-soluble bases are soluble in water. They are also soluble in alcohol. They accept a very limited amount of water without loss of viscosity.
What are four strategies for adding an aqueous or alcoholic solution to a base?
1) Change the ointment base, 2) Add a nonionic auxiliary emulsifier or emulsifier combination, such as a Tween/Span-type, 3) Add Stearyl or Cetyl Alcohol to water-soluble Polyethylene Glycol bases to improve water or alcohol absorption, & 4) Spatulate the solution and ointment base until a sufficient amount of the solvent evaporates.
What amount of solvent do you add?
General rule: Unless a prescription order specifically calls for a given amount of the solvent, use the minimum amount necessary to dissolve the powders.
What documentation of the solvent must occur?
The name of the solvent and the quantity used should be noted on the face of the prescription order or in the compounding record.
What are some thick liquids that are measured by weight rather than volume?
Coal Tar, Peru Balsam, Ichthammol, and the polysorbate-sorbitan type emulsifiers.
What are three things to do when packing an ointment jar?
1) Check for air bubbles, 2) Make it look professional, & 3) Clean the cap and jar.
How does the physical stability of ointments compare with that of suspensions or emulsions?
As semisolid dosage forms, ointments are usually more physically stable than are suspensions or emulsions, allowing more flexibility with assigning expiration dates.
What term is used to describe the phase separation of liquid ingredients from an ointment? What type of agents may be helpful in preventing this?
The phase separation of liquid ingredients from an ointment is referred to as "bleeding.” Special levigating agents, may help prevent this.
What can be done to retard the evaporation of water and drying out of an ointment base?
Glycerin or propylene glycol may be added as humectants.
What are the two actions of unmedicated creams?
1) Emollient: An agent that softens the skin or soothes irritation in skin or mucous membrane, and 2) Protective: A substance that protects injured or exposed skin surfaces from harmful or annoying stimuli.
What is a gel?
A semisolid system consisting of either suspensions made up of small inorganic particles or large organic molecules interpenetrated by a liquid.
What are two advantages of gels?
1) Gels are an excellent formulation for several routes of administration (oral, topical, vaginal, & rectal); 2) Gels can be clear formulations – generally preferred by patients – when all of the particles completely dissolve in the dispersing medium (this doesn't occur in all gels, therefore some are turbid).
How do gelling agents increase viscosity?
Gelling agents undergo a high degree of crosslinking or association when hydrated and dispersed, or otherwise dissolved, in the dispensing medium.
When is a gel a single phase system?
A gel is a single phase system when it contains linear or branched polymer macromolecules that dissolve in water and have no apparent boundary with the dispensing medium.
What are single phase gels made from synthetic or natural macromolecules called?
Mucilages
When is a gel a two-phase system?
A gel is a two-phase system when it contains small discrete particles.
What is a two-phase system gel called when the particles are large?
If the particles of a two-phase system are large, the gel is referred to as a “magma.”
It would be prudent to be able to recognize the following as common gelling agents.
Alginic acid, Bentonite, Carbopols® (now known as carbomers), Carboxymethylcellulose, Ethylcellulose, Gelatin, Hydroxyethylcellulose, Hydroxypropyl cellulose, Magnesium aluminum silicate (Veegum®), Methylcellulose, Poloxamers (Pluronics®), Polyvinyl alcohol, Sodium alginate, Tragacanth, Xanthan gum
What is clumping and when does it occur?
Clumping is when the outer molecules of the gelling agent contact the medium first and hydrate forming a surface layer that is more difficult for the medium to penetrate. Clumping happens when the gelling agent is added to the dispersing medium in a “haphazard manner.”
What gelling agents have better solubility in cold water?
Methylcellulose and poloxamers have better solubility in cold water.
What gelling agents have better solubility in warm water?
Bentonite, gelatin, and sodium carboxymethylcellulose have better solubility in warm water.
What is a neutralizer and how are they relevant to the preparation of gels?
A neutralizer is a pH adjusting chemical. Some gelling agents, such as carbomers, require neutralization in order to create a gel after wetting in the dispersing medium.
How long will it take gelling agents to completely hydrate and reach maximum viscosity and clarity?
24 to 48 hours
What percent conc. of a gel is the gelling agent?
[Gelling Agent] range from 0.5% up to 10%
When do you add the active drug in when making a gel?
It is easier to add the active drug before the gel is formed, if the drug doesn't interfere with the gel formation.
Name four gels can be ingested?
1) Carbopol® 934P, 2) Methylcellulose, 3) Hydroxypropylmethylcellulose, and 4) Sodium Carboxymethylcellulose
What are carbomers (Carbopol®)?
Carbomers are a family of polymers – having high bulk densities as a dry powder – that form acidic aqueous solutions (pH ~3), swelling up to 1000 times their original volume, and thickening to viscosities as high as 80,000 centipoise when neutralized to a pH around 5 or 6.
Describe the three essential steps to making a Carbopol Gel?
1) Slowly sprinkle all of sieved powder into water. 2) Then reduce stirring speed to avoid air bubbles. 3) Finally, add neutralizer to increase the pH.
List two inorganic bases commonly utilized as neutralizers. What type of Carbopol gel do they form?
Two inorganic bases utilized as neutralizing agents include sodium hydroxide and potassium hydroxide. These form stable, water-soluble Carbopol gels.
What organic base is commonly utilized as a neutralizer? What unique tolerance does this base bestow on a Carbopol gel?
Triethylamine (sometimes referred to as a “trolamine” salt in its protonated, salt form) is an organic base commonly utilized as a neutralizing agent for gels. Carbopol gels neutralized with triethylamine can tolerate high alcohol concentrations.
What can be added to a Carbopol gel to further increase viscosity? What can be added to decrease its viscosity?
Propylene glycol and glycerin can be added to increase viscosity. Electrolytes can be added to decrease viscosity.
What are five cellulose derivatives commonly utilized as gelling agents. Over what pH range are they effective?
The five cellulose derivatives commonly utilized as gelling agents are methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, and carboxymethylcellulose (CMC). All except CMC maintain high viscosity over a wide pH range (3 to 11). [CMC only maintains high viscosity between pH 4 and 10.]
What effect do salts have on the formation of gels from cellulose derivatives?
Salts reduce the ability of cellulose derivatives to hydrate. [Some derivatives are more sensitive to divalent and trivalent inorganic salts.]
What is the most difficult task associated with making gels from cellulose derivatives?
The most difficult task is to introduce the compounds into solvents without clumping.
Describe the three essential steps to making a cellulose derivative?
1) Sift the powders into the vortex of the rapidly stirring solvent, 2) Levigate the powder with a water miscible non-solvent such as absolute alcohol or propylene glycol, and 3) Use a blender to homogeneously mix the powder and solvent.
What are poloxamer (Pluronics®) copolymers?
Poloxamers are white, waxy, granule copolymers of polyoxyethylene and polyoxypropylene that – when dissolved concentrations ranging from 15 to 50% – form thermoreversible gels at room temperature or body temperature but, fascinatingly enough, are clear liquids when cooled to between 0 and 10 C.
What are the two components of a “PLO gels?”
PLO gels are made by combining a Pluronic F-127 gel and a lecithin/isopropyl palmitate syrup.
Prior to making a PLO gel, how are its two components made and stored?
The Pluronic F-127 gel and a lecithin/isopropyl palmitate syrup are made and stored separately.
In which of the two PLO gel component are water-soluble drugs dissolved prior to gel formulation?
Water-soluble drugs are dissolved in the Pluronic F-127 gel prior to its mixing with the lecithin/isopropyl palmitate syrup.
In which of the two PLO gel component are oil-soluble drugs dissolved prior to gel formulation?
Oil-soluble drugs are dissolved in the lecithin/isopropyl palmitate syrup prior to its mixing with the Pluronic F-127.
How are small formulations of PLO gel made?
The Pluronic F-127 gel is put in one syringe, and the lecithin/isopropyl palmitate syrup is put in another. The two syringes are connected by an adapter and the shearing caused when the two components pass through the adapter creates the PLO gel.
What is the definition of a paste?
A paste is a semisolid dosage form that contains one or more drug substances intended for topical application.
What are the two classes of pastes?
1) Single phase aqueous gel pastes, such carboxymethylcellulose sodium paste, & 2) Fatty pastes, such as zinc oxide paste.
What are the properties of a fatty paste and what function do they serve when applied?
Fatty pastes are thick, stiff ointments that do not ordinarily flow at body temperature. They serve as protective coatings over the areas to which they are applied.