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Questions and Answers
Which factor does NOT influence the choice of semisolid vehicle?
Which factor does NOT influence the choice of semisolid vehicle?
What is the primary characteristic of water-soluble bases?
What is the primary characteristic of water-soluble bases?
Which class of semisolid vehicles is most commonly used in ointment formulations?
Which class of semisolid vehicles is most commonly used in ointment formulations?
Which of the following is a common water removal base?
Which of the following is a common water removal base?
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What is the main reason for needing higher concentrations of preservatives when 5% tween 80 is present?
What is the main reason for needing higher concentrations of preservatives when 5% tween 80 is present?
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What is an important consideration for containers used in the formulation of semisolids?
What is an important consideration for containers used in the formulation of semisolids?
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Which of the following factors is NOT considered when choosing antioxidants?
Which of the following factors is NOT considered when choosing antioxidants?
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Which ingredient is commonly added to petrolatum to lower its fusion point for ophthalmic use?
Which ingredient is commonly added to petrolatum to lower its fusion point for ophthalmic use?
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Why is it important to prevent aeration during the mixing of semisolids?
Why is it important to prevent aeration during the mixing of semisolids?
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What is essential during the manufacture of emulsified semisolids?
What is essential during the manufacture of emulsified semisolids?
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Which characteristic describes absorption bases in semisolids?
Which characteristic describes absorption bases in semisolids?
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What is the primary property of semisolids that allows them to be effective for topical applications?
What is the primary property of semisolids that allows them to be effective for topical applications?
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What type of preservative is commonly used to prevent microbial spoilage in semisolids?
What type of preservative is commonly used to prevent microbial spoilage in semisolids?
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Which of the following is NOT a use of semisolids?
Which of the following is NOT a use of semisolids?
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Which of the following processes follows normal manufacturing procedures in the production of sterile preparations?
Which of the following processes follows normal manufacturing procedures in the production of sterile preparations?
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Which raw material is commonly used to increase the viscosity of mineral oils in semisolids?
Which raw material is commonly used to increase the viscosity of mineral oils in semisolids?
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What role do tonicity contributors play in pharmaceutical products?
What role do tonicity contributors play in pharmaceutical products?
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What should be included in the environmental controls during the compounding of sterile preparations?
What should be included in the environmental controls during the compounding of sterile preparations?
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Which fatty acid is commonly used as an emulsifier in water-removal creams?
Which fatty acid is commonly used as an emulsifier in water-removal creams?
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Which of the following is NOT a step in the production process?
Which of the following is NOT a step in the production process?
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What characteristic of insoluble powders is necessary to ensure a smooth texture in semisolids?
What characteristic of insoluble powders is necessary to ensure a smooth texture in semisolids?
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Which of the following emulsifiers is known as the first emulsifier used for semisolids in O/W emulsions?
Which of the following emulsifiers is known as the first emulsifier used for semisolids in O/W emulsions?
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What is the role of polyols in the formulation of semisolids?
What is the role of polyols in the formulation of semisolids?
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Which of the following oils is NOT classified as a vegetable oil commonly used in semisolids?
Which of the following oils is NOT classified as a vegetable oil commonly used in semisolids?
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Study Notes
Preservatives
- Some preservatives become ineffective in the presence of other ingredients.
- 5% Tween 80 can inactivate 80% of the total methyl paraben, requiring a higher concentration of preservatives.
- Boric acid is acceptable in ophthalmic preparations but not for nasal products due to potential toxicity when absorbed in large quantities.
- To evaluate the effectiveness of a preservative, a semisolids preparation can be contaminated with suitable organisms and the number of organisms measured over time.
Antioxidants
- The choice of an antioxidant depends on factors like toxicity, irritancy, compatibility, odor, discoloration, solubility, and stability
- Popular antioxidants include BHA, BHT, and Propyl Gallate.
Industrial Processing
- A pilot plant or small-scale production equipment is needed for developing a manufacturing procedure for a production-size batch.
- Mixing and stirring operations are essential in the preparation of semisolids.
- Aeration should be avoided to maintain stability and consistency in density.
Manufacture of Ointments
- Fusion methods are commonly used for anhydrous ointments.
- The active ingredient is dissolved in melted fats and waxes or in the vehicle, and the mixture is stirred while cooling to ensure homogeneity.
Manufacture of Emulsified Semisolids
- Three factors control the manufacturing process: mixing time, temperature, and mechanical work, including the rate of agitation.
Tonicity Contributors
- Compounds contributing to the isotonicity of a product reduce the pain of injection in areas with nerve endings.
- Buffers can serve as tonicity contributors, as well as stabilizers for pH.
Production
- Production processes for semisolids involve steps like compounding, filtration, filling, sealing, and sterilization.
Compounding
- Processing of sterile preparations follows standard manufacturing procedures and must be conducted under aseptic conditions.
- Environmental control is crucial to prevent microbial contamination.
Types of Vehicles
- Vehicles used for semisolid pharmaceutical preparations should be effective therapeutically and cosmetically appealing.
- The vehicle for a pharmaceutical preparation differs from that used in cosmetics, as penetration into the skin is not desired for cosmetics.
Factors Influencing Vehicle Choice
- The nature of the skin lesions, solubility, and stability of the drug in the base influence the choice of a semisolids vehicle.
Semisolids Vehicle Classes
- The United States Pharmacopeia (USP) recognizes four classes of semisolids vehicles:
- Hydrocarbon Bases
- Absorption Bases
- Water-Removable Bases
- Water-Soluble Bases
Hydrocarbon Bases
- Most commonly used in ointment vehicles.
- Petrolatum
- Most commonly used in ointment vehicles.
- White Ointment
- Petrolatum with 5% beeswax, typically lipophilic vehicles.
Absorption Bases
- Hydrophilic mixtures formed by adding substances miscible with hydrocarbons.
- These substances possess polar groupings such as sulfates, sulfonates, carboxyl or ether linkages (R-O-R').
- Lanolin, cholesterol, sterols, sorbitan monostearate or monoleate can be added to make hydrocarbon bases hydrophilic.
- Cold Cream is a type of W/O emulsion.
Water-Removable Bases
- O/W emulsions.
- Often referred to as “creams”.
- Examples include Vanishing Creams.
Water-Soluble Bases
- Prepared from mixtures of high molecular weight (HMW) and low molecular weight (LMW) polyethylene glycols (PEGs).
- Characteristics:
- LMW PEGs are liquids;
- Moderately HMW PEGs are unctuous (smooth and oily);
- HMW PEGs are solids.
- No water is required for their preparation.
- Suitable combinations of HMW and LMW PEGs yield products with ointment-like consistency, softening or melting upon application to the skin.
- Possess many polar groups and other linkages.
- Considered greaseless ointment bases.
Ophthalmic Ointments
- Oftentimes contain soft petrolatum, a bland absorption base, or a water-soluble base.
- May be prepared with PEGs or water-soluble gums.
- Mineral oil is frequently added to petrolatum to lower its melting point.
- All materials should be impalpable (not gritty or rough) to avoid discomfort and irritation.
- Sterilization is required for injured eyes.
Prevention from Microbial Spoilage
-
Essential considerations for preservatives:
- Stability with regard to other formula components.
- Compatibility with the chosen container material.
-
Parabens (para-hydroxybenzoate esters) are a common type of preservative.
General Considerations for Preservatives
- Containers can be a source of contamination, harboring bacterial spores or interacting chemically with preservatives.
- Examples include plastic, rubber seals and closures.
Semisolids
- Semisolids are a category of pharmaceutical preparations that include ointments, creams, cream emulsions, gels, and rigid foams.
Common Properties of Semisolids
- Ability to adhere to the surface of application for a reasonable duration before being rubbed off.
Uses of Semisolids
- Vehicles for topically applied drugs.
- Emollients (agents which moisturize or soften the skin).
- Protective or occlusive dressings on the skin.
Raw Materials for Semisolids
- The basic ingredients for semisolids include:
- Hydrocarbons
- Hydrocarbon waxes
- Oleaginous substances
- Fatty acids and alcohols
- Emulsifiers
- Polyols
- Insoluble compounds
Hydrocarbons
- Petrolatum:
- A complex mixture of semisolids containing hydrocarbon aliphatic, cyclic, saturated, unsaturated branched, and unbranched molecules in varying proportions.
- Mineral Oil:
- Obtained from petroleum.
- The lower viscosity is preferred as it is less sticky and greasy.
Hydrocarbon Waxes
- Often used to increase the viscosity of mineral oils, preventing separation from ointments.
- Example:
- Paraffin
- Ceresin Wax (a mixture of paraffin wax and ozokerite)
Oleaginous Substances
- Vegetable Oils:
- Examples include peanut oil, almond oil, sesame oil, and olive oil.
- Glycerides of mixtures of saturated and unsaturated fatty acids.
Fatty Acids and Alcohols
- Stearic Acid:
- Used in water-removable creams as an emulsifier to achieve the desired consistency.
- Stearyl Alcohol and Cetyl Alcohol (Palmityl Alcohol):
- Used as auxiliary emulsifiers and emollients.
- Sufficient quantities of stearyl alcohol create a firm cream, which can be softened by cetyl alcohol.
Emulsifiers
- Triethanolamine Stearate Soap (water-soluble soap):
- The first emulsifier used for semisolids in O/W emulsions.
- The viscosity of the cream prevents coalescence of the dispersed phase and helps stabilize the emulsion.
Polyols
- Glycerine, propylene glycol (PG), sorbitol (70%), and low molecular weight PEGs.
- Primarily used as humectants (agents that attract and retain moisture).
Insoluble Powders
- Evenly dispersed throughout the vehicle to ensure product homogeneity.
- Solid particles must be impalpable to the touch to prevent grittiness.
- Particles less than 74 microns in size (equivalent to a mesh opening in a #200 mesh sieve) are typically considered impalpable.
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Description
This quiz covers key concepts related to preservatives and antioxidants in pharmaceuticals, including their effectiveness and compatibility. You'll explore the importance of proper selection and evaluation of these additives in various formulations. Ideal for students in pharmaceutical sciences or related fields.
