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What is the primary advantage of choosing an emulsion preparation method?
What type of mortar is not suitable for preparing emulsions using the continental method?
What is the ratio of oil to water to gum in the primary emulsion using the continental method?
What is the purpose of using a rough inner surface mortar in the continental method?
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What is the name of the method that involves adding the external phase to the internal phase?
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What type of equipment is commonly used for small-scale emulsion preparation?
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What is the purpose of triturating the emulsifying agent with oil in the continental method?
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How many parts of water are added to the primary emulsion in the continental method for every four parts of oil?
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What determines the type of emulsion formed based on the Plastic or Interfacial Film Theory?
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What is the primary function of an emulsifying agent in an emulsion?
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What is a key criterion for selecting an emulsifying agent?
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What influences the stability and characteristics of an emulsion?
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What happens to the phase in which the emulsifier is more soluble?
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Why are emulsifying agents with a greater hydrophilic character more likely to promote o/w emulsions?
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What is a key property of a good emulsifying agent?
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What is the initial step in preparing an emulsion?
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What is the primary factor responsible for the stability of emulsions?
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What type of film is formed by solid particles such as Bentonite and Magnesium hydroxide?
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What is the primary characteristic of particles that form a stable film at the interface?
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What is the HLB system used for?
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What is the range of HLB values assigned to emulsifying agents?
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What does the HLB number of a surfactant represent?
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What is the characteristic of materials that are highly polar or hydrophilic?
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What is the primary function of the interfacial film in emulsions?
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Study Notes
Emulsion Preparation Methods
- Various methods are used to prepare emulsions, ranging from small-scale laboratory techniques to large-scale industrial processes.
- Each method has its advantages and is chosen based on the nature of components and desired emulsion characteristics.
Small-Scale Emulsion Preparation Methods
- Laboratory equipment used: dry Wedgwood or porcelain mortar and pestle, mechanical blenders, and simple prescription bottles.
- Three laboratory techniques are used: the continental or dry gum method, the English or wet gum method, and the bottle or Forbes bottle method.
Continental or Dry Gum Method
- Involves triturating the emulsifying agent with oil before adding water (addition of external phase to the internal phase).
- Also referred to as the 4:2:1 method, where for every four parts by volume of oil, two parts of water and one part of gum are added.
- Example: for 40 mL of oil, 20 mL of water and 10 g of gum would be employed in the primary emulsion.
- Acacia or other o/w emulsifier is triturated with oil in a dry mortar until thoroughly mixed.
- Water is added all at once, and the mixture is triturated rapidly and continuously until the primary emulsion is formed.
Stability of Emulsions
- Stability is mainly due to the strength of the interfacial film.
- Solid particles, such as bentonite and magnesium hydroxide, can form a particulate film that prevents coalescence.
Hydrophilic-Lipophilic Balance (HLB) System
- Emulsifying agents can be categorized based on their chemical makeup and hydrophilic-lipophilic balance (HLB).
- Each agent is assigned an HLB value or number indicating the substance's polarity (range: 1-20).
- Highly polar or hydrophilic materials have higher numbers, while less polar and more lipophilic materials have lower numbers.
- Emulsifying agents with a greater hydrophilic character tend to promote o/w emulsions, while those with a more hydrophobic character favor w/o emulsions.
Plastic or Interfacial Film Theory
- Emulsifying agents form a thin film adsorbed on the surface of internal phase droplets, acting as a barrier to prevent contact and coalescence.
- The stability of the emulsion depends on the toughness and flexibility of this film.
- The degree of solubility of the emulsifying agent in the two phases determines whether o/w or w/o emulsions are formed.
Factors Affecting Emulsion Formation
- Emulsifying agents, pH, and the ratio of internal to external phases influence the stability and characteristics of an emulsion.
Criteria for Selecting Emulsifying Agents
- Compatibility: emulsifying agents must not interfere with other formulation ingredients or the stability or efficacy of the therapeutic agent.
- Stability: emulsifying agents should be stable and not deteriorate during preparation or storage.
- Safety: emulsifiers should be nontoxic, safe for consumption, and have minimal odor, taste, or color.
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Description
This quiz covers various methods used to prepare emulsions, ranging from small-scale laboratory techniques to large-scale industrial processes.
