541 - Drug Delivery Systems Lab I - Exam Ii - Compounding Emulsions, Ointments, Creams, Gels And Pastes

Front 1

Define "Emulsion."

Back 1

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.

Front 2

What is the dispersed liquid in an emulsion called?

Back 2

The dispersed liquid of an emulsion is called internal or discontinuous phase.

Front 3

What is the dispersion medium in an emulsion called?

Back 3

The dispersion medium of an emulsion is called the external or continuous phase.

Front 4

Define "O/W"

Back 4

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**

Front 5

What guidelines determine if an emulsion is O/W?

Back 5

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.

Front 6

Define "W/O"

Back 6

Emulsions where water or aqueous solutions are dispersed in an oleaginous medium.

**water-in-oil emulsion**

Front 7

What guidelines determine if an emulsion is W/O?

Back 7

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.

Front 8

What three factors determine the type of emulsion?

Back 8

1) Type of Emulsifier, 2) Phase Ratio (relative amounts of oil and water), and 3) Order of Mixing.

Front 9

What are four desired properties of a liquid emulsion for oral or topical use?

Back 9

1) Fine droplets, 2) Slow aggregation of the droplets, 3) Slow creaming of the product, and 4) Ease of re-dispersion when shaken.

Front 10

What is the preferred emulsion type for oral use?

Back 10

O/W, b/c an oily feel in the mouth is objectionable

Front 11

What is the most common emulsion type?

Back 11

Oil-in-Water (O/W)

Front 12

What emulsion type do you use externally when ease of removal or a non-greasy feeling is desired?

Back 12

Oil-in-Water (O/W)

Front 13

What emulsion type is used externally when emollient, lubricating, or protective properties are desired?

Back 13

Water-in-Oil (W/O)

Front 14

What is the primary disadvantage of Oral Emulsions?

Back 14

They are usually less acceptable to patients than solutions or suspensions because of the oily feel in the mouth.

Front 15

Under what two circumstances is an oral emulsion formulated?

Back 15

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.

Front 16

What are three examples of Parenteral Emulsions?

Back 16

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)

Front 17

What is the main benefit of topical emulsions?

Back 17

When the oils are emulsified, they feel less greasy and are more aesthetically appealing to patients.

Front 18

What two functions do the oil of a topical emulsion serve?

Back 18

1) Emollience (soothing of the skin) and 2) Protection of the skin.

Front 19

Define "Emulsifying Agents."

Back 19

Emulsifying agents are surfactants that concentrate at the interface of the two immiscible phases and prevent coalesence of the droplets.

Front 20

Aside from concentrating at the interface of two immiscible phases, preventing coalescense, what other benefits do some emulsifying agents provide?

Back 20

Some agents also increase the viscosity of the system, slowing aggregation of the droplets and decreasing the rate of creaming.

Front 21

List some Cationic Synthetic Emulsifying Agents

Back 21

Benzalkonium Chlorides (there are several) & Benzethonium Chloride

Front 22

What are the three types of Anionic Synthetic Emulsifying Agents?

Back 22

1) Alkali Soaps (Na+ or K+ oleate), 2) Amine Soaps (triethanoloamine sterate), and 3) Detergents (sodium lauryl sulfate, sodium dioctyl sulfosuccinate, sodium docusate).

Front 23

What are three types of Non-Ionic Synthetic Emulsifying Agents?

Back 23

1) Spans, 2) Tweens, & 3) Glyceryl Esters

Front 24

What are three types of Natural Emulsifying Agents?

Back 24

1) Vegetable Derivatives (acacia, agar, pectin, lecithin), 2) Animal Derivatives (gelatin, lanolin, cholesterol), and 3) Semi-Synthetic (methylcellulose, carboxymethylcellulose)

Front 25

Why is Acacia unique among the natural polymer emulsifiers?

Back 25

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.

Front 26

The acacia emulsification process require the formation of what?

Back 26

The acacia emulsification process requires the formation of a primary emulsion.

Front 27

What is a "Primary Emulsion?"

Back 27

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.

Front 28

What is the ingredient ratio for primary acacia emulsions of fixed oils (vegetable and mineral)?

Back 28

(o : w : a) 4:2:1

Front 29

What is the ingredient ratio for primary acacia emulsions of volatile oils?

Back 29

(o : w : a) 3:2:1

Front 30

What is the ingredient ratio for primary acacia emulsions of essential oils?

Back 30

(o : w : a) 2:2:1

Front 31

Are preservatives required for acacia emulsions?

Back 31

Yes! Acacia emulsions are susceptible to microbial growth, especially mold.

Front 32

What is the pH range of a normal acacia emulsion? What type of preservatives are effective in that range? [Provide two specific examples.]

Back 32

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.

Front 33

What are the most common non-ionic emulsifying agents for liquid emulsions?

Back 33

The most common non-ionic emulsifying agents are combinations of Polysorbates (Tweens) with Sorbitan Esters (Spans).
"Span-Tween surfactants"

Front 34

What is the typical amount of emulsifier needed for liquid emulsions?

Back 34

5%

Front 35

What does a high HLB number mean?

Back 35

A high HLB number means the compound has more hydrophilic character.

Front 36

What does a low HLB number mean?

Back 36

A low HLB number means the compound has more lipophilic character.

Front 37

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?

Back 37

The oil soluble Spans typically have a low HLB number. They cause the oil phase to predominate and form w/o emulsions.

Front 38

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?

Back 38

The water soluble Tweens typically have a high HLB number. They cause the water phase to predominate and form an o/w emulsion.

Front 39

What HLB number range of Spans are considered lipophilic and form water-in-oil emulsions?

Back 39

1.8 to 8.6

Front 40

What HLB number range of Tweens are considered hydrophilic and favor oil-in-water emulsions?

Back 40

9.6 to 16.7

Front 41

How do you measure Spans and Tweens?

Back 41

Spans and Tweens are measured by weight.

Front 42

What physical form do Spans and Tweens have at room temperature?

Back 42

At room temp some Spans and Tweens are are solids, while others are thick liquids.

Front 43

Do all emulsions require a preservative?

Back 43

Yes - The aqueous phase is favorable to the growth of microorganisms.

Front 44

What are the two predominant manifestations emulsion instability?

Back 44

Creaming & Coalescence

Front 45

Define "Creaming."

Back 45

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.]

Front 46

Define "Coalescence."

Back 46

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."

Front 47

What is the alternate term for "Irreversible Coalescence"?

Back 47

"Cracking"

Front 48

Describe proper storage and beyond-use dating for emulsions for internal use and for external use.

Back 48

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].

Front 49

What is a cream?

Back 49

A cream is a semisolid dosage form containing one or more drug substances dissolved or dispersed in a suitable base.

Front 50

What is an ointment?

Back 50

An ointment is a semisolid preparation intended for external application to the skin or mucous membranes.

Front 51

What are the 4 classes of ointment bases?

Back 51

1) Hydrocarbon, 2) Absorption, 3) Water-removable, & 4) Water-soluble

Front 52

What are five desired characteristics of hydrocarbon or oleaginous bases?

Back 52

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.

Front 53

What are three undesirable properties of hydrocarbon or oleaginous bases?

Back 53

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.

Front 54

What are three uses of ointments, creams, gels, and pastes?

Back 54

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.

Front 55

What are the two absorption base subgroups?

Back 55

1) Anhydrous absorption bases & 2) Water-in-oil emulsions

Front 56

What are four absorption base advantages?

Back 56

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.

Front 57

What are six adsorption base disadvantages?

Back 57

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).

Front 58

What is the term “cream” reserved for?

Back 58

Water-removable, oil-in-water emulsion bases or microcrystalline dispersions of long chain fatty acids or alcohols in water.

Front 59

What are water-removable bases?

Back 59

Water-removable bases are oil-in-water emulsions or creams.

Front 60

What are four advantages of water-removable bases?

Back 60

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.

Front 61

What are five disadvantages of water-removable bases?

Back 61

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].

Front 62

What are seven characteristics of water-soluble bases (gels)?

Back 62

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.

Front 63

What amount of excess product should you make in order to make up for that which is lost during compounding?

Back 63

10% or 3 grams

Front 64

List three reasons why ointment slab preferred to pads?

Back 64

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.

Front 65

When should you use a large metal spatula?

Back 65

Large metal spatulas are used for levigation, spatulation, and incorporation of solid and liquid ingredients.

Front 66

When should you use a small metal spatula?

Back 66

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.

Front 67

When should you use a black rubber or plastic spatula?

Back 67

Black rubber or plastic spatulas are special purpose spatulas that are used when an ingredient (e.g., iodine) reacts with a metal spatula.

Front 68

List four situations when a levigating agent should not be used?

Back 68

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.

Front 69

What technique should you use to mix a smaller quantity of drug into an ointment?

Back 69

Geometric Dilution

Front 70

On what bases are levigating agents usually chosen?

Back 70

Levigating agents are usually chosen to be chemically similar to the ointment base (assuming no compatibility problems with other ingredients).

Front 71

When mineral oil is used as a levigating agent, it is usually for what two ointment bases?

Back 71

Mineral oil is typically used for 1) hydrocarbon bases and 2) absorption bases, such as those of water-in-oil.

Front 72

When glycerin is used as a levigating agent, it is usually for what two ointment bases?

Back 72

1) Water-Removable Bases & 2) Water-Soluble Bases

Front 73

What are four characteristics of coal tar?

Back 73

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)).

Front 74

How is cold tar obtained?

Back 74

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.

Front 75

What is in a coal tar topical solution?

Back 75

Coal Tar Topical Solution (LCD= Liquid Carbonis Detergens): Coal Tar: 200 g, Polysorbate 80: 50 g; Alcohol, qs 1000 mL.

Front 76

What are four factors that determine the amount of levigating agent needed?

Back 76

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].

Front 77

If the prescription doesn’t say how much levigating agent to include how much should be included?

Back 77

Include the minimum amount of levigating agent necessary to lubricate the powders.

Front 78

What concerning the levigating agent do you need to document and where?

Back 78

The name of the levigating agent and the quantity used should be noted on the face of the prescription order or the compounding record.

Front 79

Under what circumstance would you use dissolution in the preparation of an ointment?

Back 79

To dissolve a solid ingredient in a solvent or oil to allow for better mixing when it is subsequently incorporated into the ointment.

Front 80

What are the two types of solvents? [Provide examples of each].

Back 80

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)

Front 81

What is the capacity of hydrocarbon bases to absorb liquids?

Back 81

Hydrocarbon bases do not absorb any water and only very limited amounts of alcoholic solutions.

Front 82

What is the capacity of absorption bases to absorb liquids?

Back 82

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.

Front 83

What is the capacity of water-removable bases to absorb liquids?

Back 83

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.

Front 84

What is the capacity of water-soluble bases to absorb liquids?

Back 84

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.

Front 85

What are four strategies for adding an aqueous or alcoholic solution to a base?

Back 85

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.

Front 86

What amount of solvent do you add?

Back 86

General rule: Unless a prescription order specifically calls for a given amount of the solvent, use the minimum amount necessary to dissolve the powders.

Front 87

What documentation of the solvent must occur?

Back 87

The name of the solvent and the quantity used should be noted on the face of the prescription order or in the compounding record.

Front 88

What are some thick liquids that are measured by weight rather than volume?

Back 88

Coal Tar, Peru Balsam, Ichthammol, and the polysorbate-sorbitan type emulsifiers.

Front 89

What are three things to do when packing an ointment jar?

Back 89

1) Check for air bubbles, 2) Make it look professional, & 3) Clean the cap and jar.

Front 90

How does the physical stability of ointments compare with that of suspensions or emulsions?

Back 90

As semisolid dosage forms, ointments are usually more physically stable than are suspensions or emulsions, allowing more flexibility with assigning expiration dates.

Front 91

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?

Back 91

The phase separation of liquid ingredients from an ointment is referred to as "bleeding.” Special levigating agents, may help prevent this.

Front 92

What can be done to retard the evaporation of water and drying out of an ointment base?

Back 92

Glycerin or propylene glycol may be added as humectants.

Front 93

What are the two actions of unmedicated creams?

Back 93

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.

Front 94

What is a gel?

Back 94

A semisolid system consisting of either suspensions made up of small inorganic particles or large organic molecules interpenetrated by a liquid.

Front 95

What are two advantages of gels?

Back 95

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).

Front 96

How do gelling agents increase viscosity?

Back 96

Gelling agents undergo a high degree of crosslinking or association when hydrated and dispersed, or otherwise dissolved, in the dispensing medium.

Front 97

When is a gel a single phase system?

Back 97

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.

Front 98

What are single phase gels made from synthetic or natural macromolecules called?

Back 98

Mucilages

Front 99

When is a gel a two-phase system?

Back 99

A gel is a two-phase system when it contains small discrete particles.

Front 100

What is a two-phase system gel called when the particles are large?

Back 100

If the particles of a two-phase system are large, the gel is referred to as a “magma.”

Front 101

It would be prudent to be able to recognize the following as common gelling agents.

Back 101

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

Front 102

What is clumping and when does it occur?

Back 102

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.”

Front 103

What gelling agents have better solubility in cold water?

Back 103

Methylcellulose and poloxamers have better solubility in cold water.

Front 104

What gelling agents have better solubility in warm water?

Back 104

Bentonite, gelatin, and sodium carboxymethylcellulose have better solubility in warm water.

Front 105

What is a neutralizer and how are they relevant to the preparation of gels?

Back 105

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.

Front 106

How long will it take gelling agents to completely hydrate and reach maximum viscosity and clarity?

Back 106

24 to 48 hours

Front 107

What percent conc. of a gel is the gelling agent?

Back 107

[Gelling Agent] range from 0.5% up to 10%

Front 108

When do you add the active drug in when making a gel?

Back 108

It is easier to add the active drug before the gel is formed, if the drug doesn't interfere with the gel formation.

Front 109

Name four gels can be ingested?

Back 109

1) Carbopol® 934P, 2) Methylcellulose, 3) Hydroxypropylmethylcellulose, and 4) Sodium Carboxymethylcellulose

Front 110

What are carbomers (Carbopol®)?

Back 110

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.

Front 111

Describe the three essential steps to making a Carbopol Gel?

Back 111

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.

Front 112

List two inorganic bases commonly utilized as neutralizers. What type of Carbopol gel do they form?

Back 112

Two inorganic bases utilized as neutralizing agents include sodium hydroxide and potassium hydroxide. These form stable, water-soluble Carbopol gels.

Front 113

What organic base is commonly utilized as a neutralizer? What unique tolerance does this base bestow on a Carbopol gel?

Back 113

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.

Front 114

What can be added to a Carbopol gel to further increase viscosity? What can be added to decrease its viscosity?

Back 114

Propylene glycol and glycerin can be added to increase viscosity. Electrolytes can be added to decrease viscosity.

Front 115

What are five cellulose derivatives commonly utilized as gelling agents. Over what pH range are they effective?

Back 115

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.]

Front 116

What effect do salts have on the formation of gels from cellulose derivatives?

Back 116

Salts reduce the ability of cellulose derivatives to hydrate. [Some derivatives are more sensitive to divalent and trivalent inorganic salts.]

Front 117

What is the most difficult task associated with making gels from cellulose derivatives?

Back 117

The most difficult task is to introduce the compounds into solvents without clumping.

Front 118

Describe the three essential steps to making a cellulose derivative?

Back 118

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.

Front 119

What are poloxamer (Pluronics®) copolymers?

Back 119

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.

Front 120

What are the two components of a “PLO gels?”

Back 120

PLO gels are made by combining a Pluronic F-127 gel and a lecithin/isopropyl palmitate syrup.

Front 121

Prior to making a PLO gel, how are its two components made and stored?

Back 121

The Pluronic F-127 gel and a lecithin/isopropyl palmitate syrup are made and stored separately.

Front 122

In which of the two PLO gel component are water-soluble drugs dissolved prior to gel formulation?

Back 122

Water-soluble drugs are dissolved in the Pluronic F-127 gel prior to its mixing with the lecithin/isopropyl palmitate syrup.

Front 123

In which of the two PLO gel component are oil-soluble drugs dissolved prior to gel formulation?

Back 123

Oil-soluble drugs are dissolved in the lecithin/isopropyl palmitate syrup prior to its mixing with the Pluronic F-127.

Front 124

How are small formulations of PLO gel made?

Back 124

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.

Front 125

What is the definition of a paste?

Back 125

A paste is a semisolid dosage form that contains one or more drug substances intended for topical application.

Front 126

What are the two classes of pastes?

Back 126

1) Single phase aqueous gel pastes, such carboxymethylcellulose sodium paste, & 2) Fatty pastes, such as zinc oxide paste.

Front 127

What are the properties of a fatty paste and what function do they serve when applied?

Back 127

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.