Term
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Definition
| A two-phase system consisting of a finely divided solid dispersed, or suspended, in a liquid (also known as the dispersing medium |
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Term
| What can suspensions be used for pharmaceutically? |
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Definition
| Suspensions are intended for oral administration as sweetened, flavored formulations. They can be used for topical application, and are referred to as “lotions”. They may be prepared for otic or nasal application. They can also be used as non-sweetened, non-flavored formulations for many parenteral routes of administration. |
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Term
| List some reasons why a suspension would be formulated |
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Definition
1. Drug is insoluble
2. Children can't take tablet
3. To mask bad taste
4. To enhance stability |
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Term
| What are disadvantages to suspensions? |
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Definition
1. Physical (NOT chemical) instability, they tend to settle
2. Texture may be unpleasant |
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Term
| What are the two ways to increase suspension physical stability? |
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Definition
1. Flocculating agents
2. Viscosity enhancers |
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Term
| What is the purpose of a flocculating agent? |
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Definition
| To enhance particle dispersability. The suspension should not precipitate rapidly. If the particles settle at the bottom of the container, they should redisperse rapidly when shaken. |
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Term
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Definition
A less rigid or loose aggregation of particles that are held together by comparatively weak particle-to-particle bonding forces.
Flocs tend to produce a large sedimentation volume rather than a tight, compacted cake, which is characteristic of a good suspension. |
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Term
| What are flocculating agents usually made of? |
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Definition
| Electrolytes that carry an electrical charge opposite that of the net charge of the suspended particles. |
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Term
| What are some flocculating agents that aren't made of electrolytes? |
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Definition
1. Clays such as diluted bentonine magma
2. Alteration of pH
3. Surfactants |
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Term
| What is the range of concentration of viscosity enhancers? |
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Definition
| Typical concentrations of viscosity enhancers range from 0.5% to 5%. The needed viscosity will depend on the suspended particle’s tendency to settle. |
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Term
| What is the purpose of a viscosity enhancer? |
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Definition
| To reduce the difference between the densities of the suspended particles and the dispersing medium |
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Term
| List some viscosity enhancers (don't need to know all exactly) |
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Definition
∙Natural hydrocolloids – acacia, tragacanth, alginic acid, carrageenan, locust bean gum, guar gum, gelatin
∙Semisynthetic hydrocolloids – methylcellulose, sodium carboxymethylcellulose
∙Synthetic hydrocolloids – carbopol
∙Clays – bentonite, Veegum |
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Term
| What is the alcohol content of suspension vehicles Ora-Plus and Suspendol-S? |
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Definition
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Term
| How would one prepare a suspension vehicle? |
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Definition
1. Prepare a 0.5% to 5% methylcellulose dispersion or a 0.5% to 1.5% sodium carboxymethylcellulose dispersion
2. Mix 1:1 with a flavored syrup |
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Term
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Definition
The property of a fluid that is thick under normal conditions, but flow when shaken/agitated
A good quality of an ideal suspension |
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Term
| Describe the viscosity of an ideal suspension |
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Definition
| The ideal suspension should have high viscosity at low shear rates (during storage) and low viscosity at high shear rates (during shaking, pouring, or spreading). |
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Term
| List the steps to prepare a suspension |
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Definition
1. Particle size reduction
2. Wetting
3. Addition of soluble components to dispersion medium
4. Add medium in proportions to powder
5. Use vehicle to wash mixing equipment
6. qs to final volume
7. Pass through colloid mill
8. Add preservatives |
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Term
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Definition
The powder is wetted to make it more penetrable by the dispersion medium. This process reduces particle size.
(One should always use the minimal wetting amount required) |
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Term
| How do wetting agents function? |
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Definition
-Displacing the air in the crevices of the particles
-Displacing the particles
-Allowing penetration of the dispersion medium into the powder |
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Term
| List signs of suspension instability |
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Definition
Uniformity problems
Rapid Settling
Caking
Crystal growth
Difficulty resuspending
Mold and/or bacterial growth
Odor
Loss of volume |
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Term
| How would a suspension preparation be different for a neonate? |
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Definition
| Liquid suspensions for neonates should not include preservatives, colorings, flavorings, or alcohol because of the potential for each of these to cause acute or long term adverse effects. |
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Term
| Is it okay to add preservatives such as benzyl alcohol or propylene glycol to a neonatal suspension? |
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Definition
| NO, benzyl alcohol can cause a gasping syndrome characterized by a deterioration of multiple organ systems. Propylene glycol can cause seizures and stupor in some preterm infants. |
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Term
| What is an important consideration when packaging a suspension? |
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Definition
| Leave enough airspace at the top to permit adequate shaking |
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Term
| How did Tussionex ER manage to create a sustained-release liquid oral suspension? |
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Definition
| By use of a combination of ion exchange resin complex and particle coating with ethyl cellulose |
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Term
| List some common antacid oral suspensions |
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Definition
-Mylanta Liquid (aluminum hydroxide, magnesium hydroxide, simethicone)
-Maalox Suspension (aluminum hydroxide, magnesium hydroxide)
-Gaviscon Liquid Antacid (aluminum hydroxide, magnesium carbonate, sodium alginate) |
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Term
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Definition
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Term
| List some common anthementic oral suspensions |
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Definition
-Antiminth Oral Suspension (Pyrantel Pamoate)
-Mintezol Oral Suspension (Thiabendazole) |
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Term
| List some common antibacterial oral suspension |
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Definition
-Erythromycin Estolate
-Bactrim Suspension (Sulfamethoxazole and trimethoprim) |
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Term
| List some common antifungal oral suspension |
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Definition
| Nystatin Oral Suspension 100,000 U/ml |
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Term
| Describe Barium Sulfate for Suspension |
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Definition
| Employed orally or rectally for diagnostic visualization of the GI tract. |
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Term
| Describe Rowasa (Mesalamine) |
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Definition
A rectal suspension introduced in 1988 for treatment of Crohn’s disease, distal ulcerative colitis, proctosigmoiditis, and proctitis.
It is no longer available commercially, but it is compounded by pharmacists. |
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Term
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Definition
| A thermodynamically unstable mixture of heterogeneous systems consisting of at least one immiscible liquid that is intimately dispersed in another form of droplets that usually exceed 0.1 µ in diameter |
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Term
| List applications of emulsions |
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Definition
-Relatively stable mixture of two immiscible liquids
-Disguise bad-tasting oils
-Topical preparations that are easily applied and removed
-IV emulsions administer high-calorie oil to debilitated patients |
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Term
| What are the three components of a typical emulsion? |
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Definition
1. A lipid phase
2. An aqueous phase
3. An emulsifier |
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Term
What is the ratio for a fixed oil?
What is the ratio for a volatile oil? |
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Definition
4:2:1
2:2:1
oil:water:emulsifier |
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Term
| Why do emulsions require energy (agitation, ultrasonic vibration, heat)? |
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Definition
| Emulsions do not form spontaneously when liquids are mixed. Energy is required to break up the liquids, which results in an increased surface area of the internal phase. |
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Term
| Describe the English (Wet Gum) method |
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Definition
| A mucilage of the gum is prepared by triturating in a mortar acacia with twice its weight of water. The oil is then added slowly, in portions, and the mixture is triturated to emulsify the oil. |
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Term
| Describe the Continental (Dry Gum) method |
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Definition
The emulsifier is triturated with the oil until mixed.
The two parts water are added all at once. Triturate immediately, rapidly, and continuously until the creamy white primary emulsion is formed and produces a crackling sound. |
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Term
| Describe the bottle method |
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Definition
Add the acacia and 4 parts oil and shake in the capped container.
It is very important NOT to allow contact of the oil and the gum for too long, because the gum may imbibe the oil, which causes the powder to become somewhat waterproof.
The required volume of water is added all at once and the mixture is shaken thoroughly until the primary emulsion is formed. |
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Term
| Describe the Beaker Method |
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Definition
The two phases are heated individually to about 60°C to 70°C if needed.
The internal phase is then added to the external phase with stirring.
The product is removed from the heat and is gently and periodically stirred until it has cooled (congealed). |
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Term
| What is the purpose of an emulsifying agent? |
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Definition
| To minimize the tendency of the globules to coalesce to form larger globules, which eventually separate into two liquids. |
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Term
| What are three methods by which emulsifying agents aid in the formation of emulsions? |
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Definition
1. Reduction of interfacial tension
2. Formation of a rigid interfacial film
3. Formation of an electrical double layer |
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Term
| What are the three categories of emulsifying agents? |
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Definition
1. Surface-active agents
2. Hydrophilic colloids
3. Finely-divided solid particles |
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Term
| How do surface-active emulsifying agents work? |
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Definition
| They are adsorbed at oil:water interfaces to form monomolecular films that result in a decrease in interfacial tension |
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Term
| How do hydrophollic colloids emulsifying agents work? |
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Definition
| They form multi-molecular films around the dispersed particles |
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Term
| How do finely divided solid particles emulsifying agents work? |
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Definition
| They are adsorbed at the interface between the two liquid phases of the globules and form a film of particles around the dispersed globules. |
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Term
| List some anionic surface active emulsifiers |
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Definition
| -Anionic emulsifiers include various monovalent, polyvalent, and organic soaps, such as triethanolamine oleate and sodium lauryl sulfate. |
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Term
| List a cationic surface active emulsifiers |
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Definition
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Term
| List some nonionic emulsifiers |
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Definition
| sorbitan esters and the polyoxyethylene derivatives |
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Term
| Describe vegetable derivative hydrophilic colloids |
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Definition
acacia, tragacanth, agar, pectin, carrageenan, lecithin
Generally limited to use as o/w emulsifiers |
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Term
| Describe animal derivative hydrophilic colloids |
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Definition
Gelatin, lanolin, cholesterol
Generally form w/o emulsions; more likely to cause allergic reactions; subject to microbial growth and rancidity |
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Term
| Describe semi-synthetic hydrophilic colloids |
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Definition
methylcellulose, carboxymethylcellulose
Stronger emulsifiers; non-toxic; less subject to microbial growth |
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Term
| Describe synthetic hydrophilic colloids |
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Definition
Carbopols
Strongest emulsifiers; non-toxic; do not support microbial growth; limited to use as o/w emulsifiers; COST may be prohibitive. |
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Term
| List some finely divided solid particle emulsifying agents |
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Definition
Bentonite
Veegum
Hectorite
Magnesium hydroxide
Aluminum hydroxide
Magnesium trisilicate
(Usually form o/w) |
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Term
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Definition
An arbitrary scale to describe emulsifying agents
A higher HLB value indicates more hydrophillic (water-soluble) |
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Term
| What is the HLB range for an emulsifying agent? |
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Definition
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Term
| What is the HLB range for a wetting agent? |
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Definition
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Term
| What is the HLB range for a detergent? |
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Definition
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Term
| What is the HLB range for a solubilizing agent? |
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Definition
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Term
| List four tests to determine emulsion type |
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Definition
1. Drop dilution
2. Dye solubility
3. Electrical conductivity (w/o will not conduct)
4. Filter paper |
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Term
| What are some ways to enhance stability of an emulsion? |
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Definition
1. Decrease globule size of the internal phase
2. Obtain an optimum ratio of oil to water
3. Increase the viscosity of the system |
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Term
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Definition
| A problem with an emulsion where globules flocculate and concentrate in one specific part of the emulsion; often reversible |
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Term
| Define "breaking" or coalescence |
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Definition
| The film surrounding the individual globules is destroyed; irreversible |
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Term
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Definition
An emulsion inverts from one form to another (a possible problem)
Basis for the Continental Method – the initial emulsion nucleus that is formed is of the w/o type. Further additions of water eventually result in an inversion into an o/w emulsion. |
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Term
| How does viscosity change as an emulsion ages? |
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Definition
| It usually increases due to the evaporation of the external phase |
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Term
| List two examples of commercially available emulsions |
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Definition
-Castor Oil Emulsion
-Simethicone Emulsion (Mylicon Drops) |
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