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Questions and Answers
What is a primary advantage of using an aerosol container for medicinal agents?
What is a primary advantage of using an aerosol container for medicinal agents?
Which propellant types are commonly employed in aerosol systems?
Which propellant types are commonly employed in aerosol systems?
What is one of the key advantages of aerosol application over mechanical application?
What is one of the key advantages of aerosol application over mechanical application?
In aerosol formulations, what component serves as the vehicle for the product concentrate?
In aerosol formulations, what component serves as the vehicle for the product concentrate?
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Which factor is NOT considered in selecting materials for aerosol containers?
Which factor is NOT considered in selecting materials for aerosol containers?
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What characteristic of aerosol application contributes to the cooling effect?
What characteristic of aerosol application contributes to the cooling effect?
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How does proper formulation and valve control affect aerosol drugs?
How does proper formulation and valve control affect aerosol drugs?
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What is a common material used in the manufacture of aerosol containers?
What is a common material used in the manufacture of aerosol containers?
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Which type of gel is typically a two-phase system?
Which type of gel is typically a two-phase system?
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What is the role of propellants in pharmaceutical aerosols?
What is the role of propellants in pharmaceutical aerosols?
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What is a key consideration when formulating pharmaceutical aerosols?
What is a key consideration when formulating pharmaceutical aerosols?
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Which advantage is associated with aerosol delivery systems?
Which advantage is associated with aerosol delivery systems?
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What may aerosol products be designed to emit?
What may aerosol products be designed to emit?
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Why is aerosol stability important?
Why is aerosol stability important?
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Which of the following is NOT a characteristic of aerosols?
Which of the following is NOT a characteristic of aerosols?
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How does the design of an aerosol's valve assembly affect its performance?
How does the design of an aerosol's valve assembly affect its performance?
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What is the role of the actuator in a valve assembly?
What is the role of the actuator in a valve assembly?
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Which component of the valve assembly is responsible for holding the gasket in place?
Which component of the valve assembly is responsible for holding the gasket in place?
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What characteristic of medicated foams contributes to their application on the skin?
What characteristic of medicated foams contributes to their application on the skin?
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Which of the following is a requirement for medicated foams intended for severely injured skin?
Which of the following is a requirement for medicated foams intended for severely injured skin?
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What does the viscosity of the product largely determine in the context of the dip tube?
What does the viscosity of the product largely determine in the context of the dip tube?
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What type of dosage form do foams represent?
What type of dosage form do foams represent?
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How can the stability of a foam be affected regarding propellant phase?
How can the stability of a foam be affected regarding propellant phase?
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What ensures the compatibility of the mounting cup with the formulation?
What ensures the compatibility of the mounting cup with the formulation?
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Study Notes
DISPERSE SYSTEMS
- Suspensions are preparations with finely divided drug particles (suspensoid) distributed in a vehicle where the drug's solubility is minimal.
- Typically, a powder mixture containing the drug, suspending agents, and dispersing agents is diluted and agitated in a vehicle, often purified water.
FEATURES DESIRED IN A PHARMACEUTICAL SUSPENSION
- A well-prepared suspension should settle slowly and redisperse easily with gentle shaking.
- The particle size of the dispersed phase should remain relatively constant over time.
- The suspension should pour smoothly and evenly from the container.
PHYSICAL FEATURES OF THE DISPERSED PHASE
- Particle size (1-50 µm) is crucial in pharmaceutical suspensions.
- Dry milling is a common method to reduce particle size.
- Micropulverization and fluid energy grinding (jet milling/micronizing) are effective for finer particles (<10 µm).
DISPERSION MEDIUM
- Highly flocculated suspensions may settle rapidly, creating an undesirable supernatant layer.
- Suspending agents (e.g., carboxymethylcellulose, methylcellulose, microcrystalline cellulose, polyvinylpyrrolidone, xanthan gum, bentonite) are added to thicken the medium and help suspend the solid particles.
PACKAGING AND STORING OF SUSPENSIONS
- Suspensions should be packaged in wide-mouth containers with adequate airspace for shaking and pouring.
- Storage should be in tight containers protected from freezing, excessive heat, and light.
- Shaking is crucial before each use for uniform distribution of the solid in the vehicle.
EMULSIONS
- An emulsion is a dispersion of small liquid globules (dispersed phase) in a vehicle (dispersion medium) in which the dispersed phase is immiscible.
- The dispersed phase is internal, while the dispersion medium is external.
- An emulsifying agent is necessary for stable emulsions.
- Emulsions can be liquids or semisolids.
HLB SYSTEM
- The HLB system categorizes emulsifying agents based on their hydrophilic-lipophilic balance (HLB) values.
- HLB values indicate polarity.
- Low HLB values (3-6) typically produce water-in-oil (w/o) emulsions, while high HLB values (8-18) typically produce oil-in-water (o/w) emulsions.
METHODS OF EMULSION PREPARATION
- Methods for preparing emulsions include Continental (or Dry Gum) Method, English (or Wet Gum) Method, Bottle or Forbes Bottle Method, and Auxiliary Methods.
CONTINENTAL OR DRY GUM METHOD
- Also known as the 4:2:1 method (4 parts oil, 2 parts water, 1 part gum).
- Gum is triturated with oil in a mortar until thoroughly mixed.
- Water is then added all at once, and the mixture is vigorously triturated until a creamy white emulsion is formed.
ENGLISH OR WET GUM METHOD
- Similar proportions to the Continental method, but the order of mixing is different.
- A mucilage of gum is prepared by triturating gum with water.
- Oil is then added slowly in portions.
- The mixture is triturated until the oil is emulsified.
BOTTLE OR FORBES BOTTLE METHOD
- Useful for volatile or low-viscosity oils.
- Gum, oil, and then water are added to the bottle, and the mixture is shaken vigorously.
- Not suitable for viscous oils.
AUXILIARY METHODS
- Emulsions can be improved by passing them through a hand homogenizer.
- A homogenizer reduces the size of the internal phase globules.
- Not effective for very thick emulsions.
STABILITY OF EMULSIONS
- Emulsions are considered physically unstable if the internal phase forms aggregates, large globules rise to the top or bottom, or liquid separates.
GELS AND MAGMAS
- Gels are semisolid systems formed by dispersions of small inorganic or large organic molecules.
- These molecules enclose and interpenetrate liquid.
- Single-phase gels have no apparent boundaries between the liquid and molecules.
- Multiphase gels ("magmas" or "milks") consist of distinct particles.
- Gels and magmas are colloidal dispersions.
TERMINOLOGY RELATED TO GELS
- Imbibition: taking up liquid without significant volume change.
- Swelling: taking up liquid with an increase in volume.
- Syneresis: the expulsion of liquid and shrinkage of the gel.
- Thixotropy: reversible gel-sol transformation with no change in volume.
- Xerogel: a dried gel where the liquid component has been removed
CLASSIFICATION AND TYPES OF GELS
- Gels are classified as inorganic or organic based on their composition.
- Specific examples within the classes are listed
AEROSOLS
- Aerosols are pressurized dosage forms that emit a fine dispersion of liquid or solid materials.
- These contain one or more active ingredients in a gaseous medium.
- They differ from other dosage forms due to the container's function, valve assembly, and the addition of propellants.
ADVANTAGES OF AEROSOLS
- Ease of medication withdrawal without contamination.
- Protection from degradation by moisture, oxygen, and light.
- Uniform thin layer application for topical medications, possibly with cooling effect.
- Controlled particle size, enabling efficient drug delivery, especially for inhalants.
- Convenient for the user with minimal cleanup.
THE AEROSOL PRINCIPLE
- Aerosols consist of a product concentrate and a propellant.
- The propellant liquefies or mixes with the concentrate and delivers it upon activation.
AEROSOL CONTAINER
- Containers for aerosols may be glass, coated glass, metal (tin-plated steel, aluminium, stainless steel) or plastic.
- Selection factors include: compatibility, production methods, pressure tolerance, design, cost.
VALVE ASSEMBLY
- The valve assembly (actuator, stem, gasket, spring, mounting cup, housing, dip tube) controls the release of the medication.
- The actuator is the trigger.
- The gaskest and spring help seal the valve.
- The stem delivers the product.
- Mounting cup holds the valve and protects the formulation.
- Housing connects the parts.
- The dip tube brings the product to the stem.
FOAMS
- Foams are emulsions containing dispersed gas bubbles.
- They have a fluffy, semisolid consistency.
- They are often used for topical application due to the prolonged contact.
- Can be used for applications on skin or mucous membranes.
PREPARATION OF FOAMS
- Foams contain one or more active ingredients, surfactants, liquids (aqueous or non-aqueous), and propellants.
- Proper formulation and propellant selection determine the type of foam produced.
- The dispensed foam may have other properties such as coolness or disinfection abilities.
- Labels will have warning on necessary precautions.
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Description
This quiz explores the essential features and preparation methods of pharmaceutical suspensions. Understanding suspensions, their desired characteristics, and the physical properties of the dispersed phase is crucial for effective pharmaceutical formulations. Test your knowledge on how suspensions are made and their stability.
