30 Questions
Which type of oral liquid dosage form contains nearly saturated solutions of 85% sugar in water?
Syrup
What type of oral liquid contains one or more active ingredients dissolved in a vehicle with a high proportion of sucrose or a suitable polyhydric alcohol or alcohols?
Elixir
Which type of oral liquid dosage form contains suspended active ingredients in a suitable vehicle, where the suspended solids may slowly separate on keeping but are easily redispersed?
Suspension
What is defined as a dibasic or heterogeneous liquid preparation of immiscible liquids dispersed as minute globules in another liquid by adding an emulsifying agent?
Emulsion
What is the primary purpose of purifying and filtering the water used in liquid dosage forms?
To remove microorganisms and particles from the water
Which type of oral liquid dosage form usually contains Ethanol (95 per cent) or a dilute Ethanol in its vehicle?
Elixir
What instrument is used to measure viscosity in a suspension?
Brookfield viscometer
How is particle size determined in a Coulter counter?
By passing through a small aperture causing a change in impedance
What keeps particles suspended in a medium?
Brownian movement
Which law assumes dilute suspensions, spherical particles, and absence of interference in relation to sedimentation?
Stokes' law
What does the sedimentation volume (F) indicate?
Ratio of final to original sediment volume
Which method is used for estimating particle size with a micrometer?
Optical microscopy
What is the process that leads to larger droplet size over time in emulsions?
Ostwald ripening
What is the main factor that influences globule size distribution in emulsions?
Phase volume ratio
What can cause irreversible damage to emulsions?
Coalescence
What is the maximum dispersed phase concentration in an ideal emulsion?
Not greater than 74%
What can lead to emulsion instability if it occurs for extended periods?
Creaming
What causes emulsions to change their physicochemical properties and become unstable?
Oxidation and microbial contamination
What is the purpose of the light transmission test in syrup quality evaluation?
To measure syrup color and clarity
Which parameter is crucial for patient adherence and product stability in pharmaceuticals?
Appearance and pH
What is the purpose of emulsifying agents in emulsions?
To stabilize thermodynamically unstable systems of immiscible liquid phases
Why is pH adjustment necessary in medicated syrups?
To ensure drug stability
What is the purpose of viscosity measurement in elixirs?
To determine viscosity changes during aging
What is the primary function of HPLC and UV spectroscopy in pharmaceuticals?
To detect the strength of active pharmaceutical ingredients
What is the primary difference between microemulsions and nanoemulsions?
Microemulsions are thermodynamically stable, while nanoemulsions are kinetically stable.
How can o/w emulsion be differentiated from w/o emulsion using the dye solubility test?
o/w emulsion appears red when mixed with oil-soluble dyes under a microscope.
What is the result of flocculation in an emulsion?
Aggregation of droplets without any change in primary droplet size due to insufficient repulsion.
What factors can help reduce creaming in an emulsion?
Decreasing globule size, decreasing density difference, and increasing the viscosity of the continuous phase.
Why is an optimum viscosity desirable for good emulsion stability?
It reduces both flocculation and creaming.
What tests can be used to differentiate between o/w and w/o emulsions?
Conductivity, dye solubility, and dilution tests.
Study Notes
- Emulsions come in various sizes and types: 1. Microemulsions (< 1 nm, thermodynamically stable), 2. Nanoemulsions (10-1000 nm, kinetically stable), 3. Macroemulsions (0.2 to 50 mm, kinetically stable), and 4. Multiple/double emulsions (o/w/o or w/o/w, kinetically or thermodynamically stable).
- Nanoemulsions are kinetically stable but will eventually separate, while microemulsions are thermodynamically stable and will not separate even after a long time.
- Emulsions can be differentiated using tests such as conductivity, dye solubility, and dilution.
- Conductivity test: o/w emulsion conducts electricity as water is the external phase.
- Dye solubility test: o/w emulsion appears red when mixed with oil-soluble dyes under a microscope.
- Dilution test: o/w emulsion can be diluted with water, while w/o emulsion can be diluted with oil.
- Emulsion stability is essential and can be affected by issues such as creaming or sedimentation, cracking, and phase inversion.
- Flocculation is the aggregation of droplets without any change in primary droplet size. It is a result of insufficient repulsion between droplets.
- Creaming or sedimentation can be observed when external forces exceed thermal motion, leading to a concentration gradient and a layer of larger droplets forming at the surface or bottom of the emulsion.
- Factors affecting creaming include the size of the globules, the density difference between the phases, and the viscosity of the continuous phase.
- Decreasing globule size, decreasing density difference, and increasing the viscosity of the continuous phase can help reduce creaming.
- An optimum viscosity is desirable for good emulsion stability as it reduces both flocculation and creaming.
- Emulsion stability is important for maintaining the appearance, accurate dosage, and preventing the probability of globule coalescence.
Test your knowledge about emulsion stability with this quiz. Learn about the differences between thermodynamically stable and kinetically stable emulsions, as well as the characteristics of nanoemulsions and microemulsions.
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