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Questions and Answers
Which of the following options is NOT a characteristic of a suitable levigating agent?
What type of base is mineral oil typically used with?
When incorporating a solid that is difficult to grind, which method can be utilized effectively?
Which levigating agent is NOT suitable for use with a W/O emulsion base?
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Which of the following solvents can be classified as water-miscible solvents?
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Which ingredient could be dissolved for incorporation into an ointment base when dealing with difficult solids?
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What is a critical step when selecting a solvent for a formulation?
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Which emulsion type allows for the incorporation of limited amounts of oil?
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Which statement about hydrocarbon bases is true?
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How should the amount of solvent be managed in a formulation?
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Which of the following is an example of a lipophilic solvent?
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What should be checked for solvent compatibility?
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When incorporating an aqueous solution into a hydrophobic base, which type allows for this without significant issues?
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Which base type is known to penetrate the skin the least?
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Which solvent is most compatible for improving drug solubility in the stratum corneum?
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What method is commonly used to dissolve active ingredients in topical formulations?
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Which type of emulsion would likely provide a lightweight consistency for topical application?
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Which penetration enhancer is characterized as an anionic surfactant?
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Which class of bases provides a significant emollient and occlusive effect?
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What type of base allows for easy removal with water?
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Which fatty acid is primarily used as a penetration enhancer in topical formulations?
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Which category of surfactants contains no charge and is typically used in emulsions?
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What is the primary characteristic of endodermic bases?
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Which of the following is a characteristic of water-removable bases?
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What is true regarding the emollient properties of water-soluble bases?
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Which statement correctly describes the formulation of water-removable bases?
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Which of the following factors influences the selection of an appropriate ointment base?
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What is a common characteristic of both water-soluble and water-removable bases?
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Which type of emulsion is classified as water-removable?
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What happens to water-removable bases upon application?
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Which of the following bases can consistently incorporate solid active ingredients effectively?
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Which of the following is a common type of water-removable base?
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What is the effect of adding water to a water-soluble base?
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What is a characteristic of hydrocarbon (oleaginous) bases?
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Which of the following is a reason for selecting a proper ointment base?
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What is a common property of water-soluble bases in ointment formulations?
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Which of the following describes the incorporation process in ointment preparation?
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Which of the following is not an ideal characteristic of an ointment base?
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What type of emulsion bases does NOT include water-in-oil (W/O) emulsions?
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Which of the following ointment bases is characterized as an effective occlusive dressing?
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What is a disadvantage of using hydrocarbon bases in ointment formulations?
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Which of the following statements is true regarding absorption bases?
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Which ointment base is classified as an oleaginous base and is known for being non-staining?
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What distinguishes a pseudoplastic fluid from a Newtonian fluid?
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In which scenario is thixotropy particularly beneficial for pharmaceutical formulations?
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What is the primary concern regarding Pseudomonas aeruginosa in topical preparations?
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Which type of ointment base is known for containing oleaginous components?
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What is a characteristic function of humectants in dermatological products?
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Which characteristic differentiates hydrogels from organogels?
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Why are composition specifics of ointment bases important when incorporating aqueous materials?
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What defines plastic flow in concentrated suspensions with flocculated particles?
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Which type of semisolid formulation is ideal for applying to moist, weeping lesions?
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What is a significant effect of dilatant materials during processing?
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Study Notes
Ointment Bases
- Hydrocarbon Bases are insoluble in water, anhydrous, and non-absorbing.
- Absorption Bases can absorb water and are categorized as anhydrous or water-in-oil (W/O) emulsions.
- Water-Removable Bases evaporate water leaving a thin film.
- Water-Soluble Bases are anhydrous and do not contain oily compounds.
Classification of Ointment Bases
- Hydrocarbon Bases are anhydrous, insoluble in water, and effective occlusive dressings.
- Absorption Bases can be anhydrous or W/O emulsions; anhydrous bases can absorb large amounts of water and W/O emulsions can absorb smaller amounts.
- Water-Removable Bases are easily washable, non-greasy, and generally more preferable to patients.
- Water-Soluble Bases are completely water-washable, non-occlusive and less emollient.
Ointment Base Characteristics
- Hydrocarbon Bases are greasy, emollient, difficult to wash, and not water-absorbing.
- Absorption Bases have a moderate greasy feel, are emollient, difficult to wash, and absorb water.
- W/O Emulsion Bases are less greasy than hydrocarbon bases, have moderate emollient properties, are slightly difficult to wash, and absorb a small amount of water.
- O/W Emulsion Bases have a creamy appearance, are non-greasy, non-occlusive, and absorb a small amount of water.
- Water-Soluble Bases have no greasy feeling, are not emollient, are easily washed, and absorb water.
Levigation
- Levigating agents should be non-sensitizing, non-allergenic, non-volatile, and should be compatible with the ointment base.
- The right levigating agent should be chosen to avoid incompatibility with the base and the solid being incorporated.
- Levigating agents should be chemically similar to the ointment base, such as mineral oil for petrolatum.
Dissolution
- Solvents are used to dissolve soluble solids prior to adding them to the ointment base.
- Solvents should be considered if the solid is difficult to grind or if the solid is incompatible with the ointment base.
- Solvents should be compatible with the ointment base and other ingredients in the formula.
Penetrant Enhancers
- Penetrant enhancers improve drug solubility in the stratum corneum to increase drug diffusion through the skin.
Criteria for Selecting an Ointment Base
- Key considerations include the desired drug release rate, the site of drug action, and the desired level of skin penetration.
Topical Dosage Forms
- Ointments are semi-solid preparations intended for external application to the skin.
- Ointments are typically classified according to their interaction with water and their physical properties.
Rheology, Viscosity & Fluidity
- Rheology: The study of the flow of matter, especially under stress.
- Viscosity: A measure of a fluid's resistance to flow. Higher viscosity means more resistance.
- Fluidity: The opposite of viscosity; a measure of how easily a fluid flows.
- Shear rate: The rate of change of velocity across a fluid. Higher shear rate means the fluid is moving faster.
- Shear stress: The force per unit area required to deform a fluid. Higher shear stress means the fluid is being pushed harder.
Newtonian & Non-Newtonian Fluids
- Newtonian: Fluids with a constant viscosity, regardless of shear rate. Examples include water, honey, and oil.
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Non-Newtonian: Fluids with viscosity that changes with shear rate.
- Pseudoplastic: Viscosity decreases with increasing shear. Examples include polymers in solution like shampoo, hair gel, and some paints.
- Dilatant: Viscosity increases with increasing shear. Examples include suspensions with high solid content like cornstarch in water.
- Plastic: Requires a minimum shear stress (yield value) before flow begins. Examples include flocculated suspensions like toothpaste, creams, and ointments.
Thixotropy
- Thixotropy: A time-dependent property where a fluid's viscosity decreases with longer periods of shear stress. As shear stress is removed, viscosity slowly recovers.
- Pharmacy Applications: Thixotropic materials are useful for products requiring a stable, easy-to-apply consistency, but also a fluidity upon application.
Dermatological Products
- Topical: Applies to the skin's surface.
- Transdermal: Penetrates through the skin to deliver medication.
- Emollients: Soften and smooth skin.
- Humectants: Attract and retain moisture.
- Stiffening Agents: Increase the viscosity or consistency of a formulation.
- Protectants: Form a barrier on the skin to prevent irritation or moisture loss.
- Rubefacients: Produce redness and warmth on the skin.
- Counterirritants: Relieve pain by creating a sensation of irritation.
- Antioxidants: Prevent or inhibit oxidation.
- Penetration Enhancers: Increase the permeability of the skin to allow medication to pass through.
- Ointments: Semisolid preparations for topical application.
- Creams: Semisolid, emulsion-based preparations for topical application.
- Pastes: Thick, stiff semisolid preparations for topical application.
- Plasters: Medications in a solid or semisolid form meant to adhere to the skin.
- Glycerogelatins: Semisolid preparations containing glycerin and gelatin.
- Gels: Semisolid preparations with a jelly-like consistency.
- Lotions: Thin, liquid preparations for topical application.
- Liniments: Liquid preparations for topical application, typically containing oil and alcohol.
- Collodions: Liquid preparations that form a film on the skin upon drying.
- Topical powders: Fine, dry preparations for topical application.
- Sticks: Solid preparations for topical application.
Ointment Bases
- Oleaginous: Oil-based, non-aqueous.
- Absorption: Contain oleaginous components that can absorb water.
- Water-Removable: Can be washed off with water.
- Water-Soluble: Water-based, non-oleaginous.
Topical Formulation Considerations
- Levigating Agents: Used to reduce the particle size of solids in ointments to improve smoothness.
- Pseudomonas aeruginosa & Staphylococcus aureus: These bacteria are of concern because they can cause skin infections and are commonly found in topical preparations.
- Preservatives: Parabens and benzoic acid are common preservatives used to prevent microbial growth.
- Moist, Weeping Lesions: Use a water-removable or water-soluble ointment base; these bases will not further irritate the skin.
- Dry, Scaly Lesions: Use an oleaginous or absorption base; these bases will help to moisturize and soften the skin.
Gels & Liniments
- Hydrogels: Gels containing water as the primary solvent.
- Organogels: Gels containing a non-aqueous solvent like oil or alcohol.
- Thermoreversible Gels: Gels that change their viscosity with temperature. This is helpful as it allows for easier application at room temperature but maintains a firmer consistency when applied to the skin.
- Carbomers: Synthetic polymers that form gels when in contact with water.
- Liniments: Should not be applied to bruised skin because the alcohol content can cause further irritation.
- Collodion: Camphor is used to provide antiseptic properties, and castor oil acts as a film-forming agent to create a protective layer on the skin.
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Description
This quiz covers the various types of ointment bases used in pharmaceutical applications. Learn about hydrocarbon bases, absorption bases, water-removable bases, and water-soluble bases, along with their characteristics and classification. Test your knowledge on the properties and uses of these bases in formulation science.
