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100 Cards in this Set
- Front
- Back
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Define ointments
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Semi-solid preparations intended for external application to the skin or mucous membranes; general definition that includes creams, lotions, gels, etc
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Ointment is a ____ dosage form; what are the disadvantages?
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Bulk dosage form; (1) Require patients to measure the dose (2) Less convenience and accuracy (3) Typically has a low residence time, meaning frequent dosing and decreased patient convenience
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Ointment is a ____ dosage form; what is the advantages?
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Bulk dosage form; Greater dosing flexibility
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What are the advantages of ointment route of administration?
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Used commonly to deliver locally-acting drugs (1) greater effectiveness (2) faster onset of action (3) less ADRs
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Ointments are most commonly used to deliver ____ drugs
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locally-acting
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What are some non-pharmacological effects of ointment bases?
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(1) Emollient (soothing), protective barrier, occlusive (decreases water loss from skin), lubricant (2) absorb bodily fluids (3) irritation, allergic reaction
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In regards to dermatologic administration, what is the major barrier to drug absorption?
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Stratum corneum - made of keratinized epidermal cells; high lipid content
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In regards to dermatologic administration, the duct of sweat gland and hair have _____ drug access
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Easy, but small overall SA
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What are the paths to systemic circulation in the skin?
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arteries and veins, but typically very small drug amounts reach these locations, thus low ADRs
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What are the 4 different routes of administration for ointments?
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(1) Dermatological/skin (2) Rectal/Vaginal (3) Nasal (4) Ophthalmic
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What is the concern regarding ophthalmic administration of ointments?
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Sterility
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What is rheology?
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The study of flow with respect to viscosity
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What is viscosity?
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A measure of the resistance to flow in response to an applied stress or force
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What does viscosity influence/affect?
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(1) Ease of application (2) Residence time
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Increased viscosity - ____ ease of application, ____ residence time, ____ dosing frequency, ____ effectiveness
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Decreased ease of application, Increased residence time, Decreased dosing frequency, Increased effectiveness
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Describe ointments with Newtonian flow
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Materials that have a constant viscosity regardless of the sheer stress or force applied to the material
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What type of compounds typically have Newtonian flow?
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Pure compounds
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What is the slope like in a Newtonian flow graph?
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Constant (positive slope) with no y-intercept; no force - no flow
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What are the different non-Newtonian flows?
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(1) Plastic flow (2) Pseudoplastic flow (3) Dilatant flow
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Describe ointments with non-Newtonian flow
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Materials that have a changing viscosity depending upon the applied sheer stress or force
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What type of compounds typically have non-Newtonian flow?
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Non-pure materials, pharmacological preparations
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Describe plastic flow
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(1) Flow does not begin until a particular sheer stress/yield stress is achieved (2) Once flow begins, it behaves in a Newtonian fashion
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Which type of flow is common with physical interaction between molecules/particles?
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Plastic flow
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Which type of flow is common with pure compounds?
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Newtonian flow
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What is the slope like in a Plastic flow graph?
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Constant (positive slope) with y-intercept, which reflects the yield stress where the material is stretching with applied stress/force
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Describe pseudoplastic flow
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(1) Flow begins immediately (2) As the sheer stress increases, viscosity decreases (sheer-thinning)
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Which type of flow is common with polymers?
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Pseudoplastic flow
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What is the slope like in a Pseudoplastic flow graph?
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Decreasing slope as F/A is increasing
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What are the effects of Pseudoplastic flow in terms of product administration?
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(1) Increased ease of application (2) Decreased residence time (usually in response to the force applied)
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Describe dilatant flow
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(1) Flow begins immediately (2) As the sheer stress increases, viscosity increases (sheer-thickening)
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What is the slope like in a Dilatant flow graph?
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Increasing slope as F/A is increasing
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Describe ointments with thixotropic flow
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Materials that exhibit a particular flow behavior as sheer stress is increased, but exhibit a different behavior once the sheer stress is decreased
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What are the different excipients for ointment preparation?
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(1) hydrocarbon/oleaginous bases (2) absorption bases (3) emulsion bases (4) water-soluble bases (5) gels
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What are the characteristics of a hydrocarbon/oleaginous base?
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(1) greasy feeling - decreased patient acceptance (2) emollient/protective (3) occlusive (4) difficult to wash off (5) does NOT absorb water
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What are examples of hydrocarbon/oleaginous bases?
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(1) Petrolatum (2) White petrolatum (3) Yellow ointment (petrolatum and yellow wax) (4) White ointment (white petrolatum and white wax)
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Describe absorption bases
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Contain hydrocarbons and surfactants
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What is the function of surfactants in absorption bases?
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Allow for the inclusion of aqueous liquids; decreases viscosity
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What are the characteristics of an absorption base?
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(1) greasy feeling - decreased patient acceptance (2) emollient/protective (3) occlusive (4) difficult to wash off (5) Absorbs water
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What are examples of absorption bases?
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(1) Hydrophilic petrolatum (white ointment, cholesterol as surfactant, stearyl alcohol to increase viscosity) (2) Anhydrous lanolin (3) Aquaphor
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What is a concert with anhydrous lanolin, and what kind of excipient is it?
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Prepared from sheep wool - possible allergic reaction; absorption base
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Describe Water-in-Oil (W/O) emulsion base
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Primarily contain hydrocarbons (continuous phase) with surfactants and some water (dispersed phase)
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What are the different kinds of emulsion bases?
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(1) Water-in-Oil (W/O) emulsion base (2) Oil-in-Water (O/W) emulsion base
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Describe Oil-in-Water (O/W) emulsion base
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Primarily contain water (continuous phase) with surfactants and some hydrocarbons (dispersed phase)
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Describe emulsion bases
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Two phase system - dispersed phase within a continuous phase
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What are examples of water-in-oil emulsion bases?
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(1) Lanolin (2) Cold cream (3) Eucerin
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What are examples of oil-in-water emulsion bases?
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(1) Hydrophilic ointment (2) Vanishing cream
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Describe water-soluble bases
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Contain neither hydrocarbons nor water
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What are examples of water-soluble bases?
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Polyethylene glycol ointment (i.e. PEG 400 liquid and PEG 3350 solid, blended to create a semi-solid)
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What are characteristics of emulsions?
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(1) greasy feeling - decreased patient acceptance (2) emollient/protective (3) occlusive (4) difficult to wash off (5) Absorbs water
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What are characteristics of water-soluble bases?
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(1) emollient/protective (2) absorbs water
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Describe gels
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Contain dispersions of gelling agents in water
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What are examples of gels?
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(1) Cellulose derivatives (i.e. methylcellulose) (2) Natural gums (i.e. tragacanth) (3) Synthetic gums (i.e. poloxamer)
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What are characteristics of gels?
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(1) emollient/protective (2) absorbs water
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What are the concerns regarding water-soluble bases and gels?
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Being too diluted or actually breaking down in water
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What are the different ways of preparing ointment bases?
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(1) Incorporation (2) Fusion (3) Fusion with emulsification
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Describe incorporation
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Simple blending of semi-solid materials using trituration with a glass mortar and pestle or spatulation on an ointment tile
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What are the advantages/disadvantages of ointment tiles?
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Advantage - ideal for spatulating ointment ingredients, some have rough surface to help reduce particle size; Disadvantage - potent drug could be lost, staining could occur
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What are the advantages/disadvantages of ointment pads?
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Advantage - speedy cleanup (top sheet simply removed and discarded); Disadvantage - tends to soak up liquid ingredients and cannot withstand significant pressure
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What are the advantages/disadvantages of ointment mills?
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Advantage - used on both small and large scales, produces smooth texture; Disadvantage (Limitation) - products must still be spatulated/mixed to ensure uniformity
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Describe fusion
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(1) Ingredients are placed in a beaker and slowly melted with heat (2) The mixture is stirred while cooling to room temperature
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When is fusion used?
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For bases containing miscible waxy materials (i.e. beeswax, paraffins, stearyl alcohol, or high MW PEG)
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Can heat labile and volatile compounds be added in fusion?
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Yes, they should be added upon cooling to minimize decomposition and loss
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Describe fusion with emulsification
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(1) The formula is separated into two phases (aqueous and oil) and placed into separate beakers (2) Both phases are slowly heated to melt (3) The phases are removed from heat and the aqueous phase is slowly added to the oil phase with continuous stirring
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Can heat labile and volatile compounds be added in fusion with emulsification?
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Yes, they should be added upon cooling to minimize decomposition and loss
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When is fusion with emulsification used?
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For bases containing both oil- and water-miscible materials, one of which is a waxy solid (emulsification - to mix the oil- and water-miscible phases/requires a surfactant)
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In fusion with emulsification, what is the purpose of adding the aqueous phase slowly to the oil phase?
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To minimize loss of material
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In fusion with emulsification, what is the purpose of stirring the mixture while cooling to room temperature?
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To prevent solidification and separation of the waxy materials
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For preparation of ointment drug product, what must be done to incorporate poorly soluble solids?
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(1) Triturate solids to fine powder (2) Levigating powder with just enough ointment base on ointment tile (3) Geometrically spatulate the rest of ointment base to mixture
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What does levigating mean?
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wetting of the powder (i.e. drug), such as in incorporating drug with ointment base on ointment tile
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When is a levigating agent used?
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If the powder does not easily incorporate into the base
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What are examples of levigating agents?
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(1) Mineral oil for greasy bases (2) Glycerin for water-miscible bases
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For preparation of ointment drug product, what must be done to incorporate soluble solids and liquids?
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(1) Dissorlve soluble solids in a minimal amount of an appropriate solvent (2) Spatulate all of the liquid with just enough ointment base on an ointment tile (3) Geometrically spatulate the rest of the ointment base with the mixture
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What are the different ways to dispense ointment?
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(1) Ointment jars (2) Ointment tubes
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What are the advantages of pastes?
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(1) Increased protective barrier (2) Some absorption of H2O onto particle surface (3) Decreased greasy feeling (4) Increased viscosity - Increased residue time
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What are the disadvantages of pastes?
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(1) Decreased occlusion (2) Decreased emollient effect (3) Decreased ease of application
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What does alligation mean?
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A mathematical method of solving problems that involve the mixing of preparations possessing different percentage strengths
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When is alligation alternate used?
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When the percentage strengths of all components are known but at least two quantities are unknown
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When is alligation medial used?
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When the quantities of all components are known but one fo the percentage strengths is unknown
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Describe the DNUB dates of ointments
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(1) Solids - 6 mo/25 percent rule (2) Aqueous - 14 days in fridge (3) Other - Intended duration of use or 30 days
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What is a chemical stability concern in ointments?
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PEG bases may (1) facilitate drug oxidation and (2) react with dispensing containers made using polystyrene
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What is a microbial stability concern in ointments?
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Bases containing water have a greater risk of microbial growth, and is a concern with products applied to compromised skin
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What may be added to prevent microbial growth? Example?
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Preservatives (i.e. benzyl alcohol)
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What are the physical stability concerns in ointments?
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(1) Drying - bases containing water may dry out through evaporation (2) Bleeding - separation of liquid and semi-solid ingredients
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What is the purpose of humectants? Examples?
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Used to prevent water loss (humectants are typically hygroscopic); glycerin and sorbitol
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When does ointment bleeding occur most?
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Most common with emulsion bases (very unstable mixtures)
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Describe the ideal ointment performance
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The drug should escape the ointment and be retained within (topical delivery) or pass through (transdermal delivery) the site of application
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How is residence time of an ointment related to its percutaneous absorption?
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Increased residence time increases absorption
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How can the rate of percutaneous absorption be increased?
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(1) Increased application area (2) Add more drug to the dosage form (3) Increased Km (4) Lower drug MW (also increased temperature) (5) Decreased membrane thickness (6) Increased k (partition coefficient)
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Describe k (partitioning coefficient)
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Solubility (stratum corneum)/Solubility (dosage form)
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What can be done to increase absorption of salt forms?
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Decrease hydrophilicity
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What can be done to increase absorption of non-salt forms?
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Increase hydrophilicity
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Non-salt form (i.e. Fluocinonide) is less/more hydrophilic?
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Less
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A greater percent response indicates a _____ absorption
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greater
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Increasing the percent of propylene glycol leads to a more ____ base
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hydrophilic
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What is the function of permeation enhancers? What are the different kinds?
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Increase skin permeability by reversibly damaging or altering the physicochemical nature of the stratum corneum and reducing its diffusional resistance; (1) chemical (2) iontophoresis
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What are examples of chemical permeation enhancers?
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(1) Lecithin (2) Isopropyl palmitate (3) DMSO - Dimethyl sulfoxide; (1) and (2) are typically added to poloxamer gel to form transdermal PLO gel products
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What is iontophoresis?
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Application of an electric current to the skin
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What are the miscelleneous semi-solids?
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(1) Plasters (2) Glycerogelatins
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Describe plasters; Example?
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Drug is incorporated into a solid or semi-solid adhesive mass, which is spread onto a paper, fabric, or plastic backing; Example - Salicylic acid plaster
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Describe glycerogelatins; Example?
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Plastic masses containing gelatin, glycerin, water, and a medicinal substance such as zinc oxide. (1) The mass is melted and applied to aa with fine brush (2) The mass hardens and is usually covered with a bandage; Example - Zinc gelatin
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