76 Questions
What is the purpose of Carbopol 980 in a gel formulation?
To act as a gelling agent
What type of bonds are responsible for physical crosslinking in hydrophilic polymers?
Van der Waals interactions and crystallites
What is the process by which a gel takes up water or solvent and increases in volume?
Swelling or imbibition
What is the term for the process by which a gel contracts spontaneously and exudes some fluid medium?
Syneresis
What is the term for the property of some gels to turn into a sol on shaking and reset to the gel on standing?
Thixotropy
What type of solvents are used in the preparation of organogels?
Organic (non-polar) solvents
What is the term for the process of self-assembly of low-molecular-weight gelators (LMWGs) to give polymer-like fibers?
The gelation process
What is the purpose of Poloxamer 124 in a gel formulation?
To act as a surfactant
What is the primary purpose of pastes in the treatment of oozing lesions?
To absorb secretions and protect the affected area
What is the characteristic consistency of pastes?
Stiff and non-flowable
What is the purpose of using a hydrocarbon base in pastes?
To create a soft and glossy base
Which method of preparation involves melting all bases and wax with continuous stirring?
Fusion method
What is the purpose of using polydimethylsiloxane in pastes?
To act as an additional hydrophobic solvent
What is the primary difference between a single-phase aqueous paste and a fatty paste?
One has a water-miscible base and the other has a hydrocarbon base
What is the purpose of using preservatives in pastes?
To prevent the growth of microorganisms
Which of the following is NOT a type of paste?
Ointment
What is the main characteristic of stimuli-responsive gels?
Drastic change in properties in response to external stimuli
What is the primary function of an occlusive vehicle in a topical preparation?
To enhance penetration of the active ingredient
What type of structure is formed by bentonite or kaolin in a gel?
Lamellar structure
What is the term for gels in which the vehicle has been removed, leaving a polymer network?
Xerogel
Why is it important to match the type of preparation with the type of lesions and site of application?
To ensure the vehicle does not interfere with the action of the active ingredient
What should be done to the affected area before applying a topical medication?
Clean and dry the affected area
Why is it important to instruct the patient on the proper amount of topical agent to use?
To ensure the correct dose of the active ingredient
What is the recommended practice when handling topical agents?
Wash hands before and after use
What is the primary characteristic that distinguishes organic gels from inorganic gels?
The type of colloidal particles
What is the term for the behavior of gels that exhibit a decrease in viscosity with increased shear force?
Pseudoplasticity
What is the purpose of the EDTA in Adapalene gel?
To chelate metal ions
What is the nature of the colloids in hydrogels?
Large organic molecules
What is the function of the Carbopol 980 in Adapalene gel?
To act as a gelling agent
What is the characteristic of the particles in gels that restricts their movement?
Their three-dimensional network
What is the term for the process of sedimentation of particles in gels over time?
Sedimentation
What is the purpose of the Poloxamer 124 in Adapalene gel?
To act as a surfactant
What is the primary function of Carbopol 980 in Adapalene gel?
Gelling agent
Which excipient is responsible for stabilizing the formulation in Adapalene gel?
EDTA sodium
What is the role of Propylene glycol in Adapalene gel?
Cosolvent
Which excipient is used to adjust the pH of Adapalene gel?
Sodium hydroxide
What is the primary function of Methylparaben in Adapalene gel?
Preservative
Which excipient is responsible for creating a consistent texture in Adapalene gel?
Carbopol 980
What is the role of Poloxamer 124 in Adapalene gel?
Surfactant
Which excipient is used as a solvent in Adapalene gel?
Purified water
What is the primary function of Carbopol 980 in Adapalene gel?
Gelling agent
What is the function of Methylparaben in Adapalene gel?
Preservative
What is the role of EDTA in Adapalene gel?
Chelating agent
What is the function of Poloxamer 124 in Adapalene gel?
Surfactant
What is the primary function of Sodium hydroxide in Adapalene gel?
pH adjuster
What is the role of Propylene glycol in Adapalene gel?
Cosolvent
What is the primary function of a hydrocarbon base in pastes?
To serve as a vehicle for the active ingredient
Which of the following excipients is a lipophilic antioxidant?
BHA
What is the primary function of a chelating agent like EDTA in a gel formulation?
To stabilize the formulation by removing impurities
What is the purpose of using preservatives in pastes?
To prevent microbial growth and spoilage
Which type of gels contain gelling agents like natural or synthetic polymers?
Organic gels
What is the characteristic of zinc oxide paste that makes it suitable for diaper rash?
It is a porous and protective coating
What is the purpose of using emulsifying ointment as a base in pastes?
To facilitate the dispersion of powdered ingredients
What is the primary function of a preservative like Methylparaben in a gel formulation?
To prevent microbial growth and spoilage
What is the function of castor oil in zinc oxide paste?
It is a hydrophobic solvent
What is the primary function of a surfactant like Poloxamer 124 in a gel formulation?
To enhance spreadability and skin feel
What is the primary function of a gelling agent like Carbopol 980 in a gel formulation?
To create a three-dimensional network and provide structure
Which excipient is responsible for adjusting the pH of Adapalene gel?
Sodium hydroxide
What is the primary function of Carbopol 980 in Adapalene gel?
To provide a gelling agent
What is the function of Methylparaben in Adapalene gel?
To function as a preservative
What is the primary function of EDTA in Adapalene gel?
To function as a chelating agent
What is the function of Poloxamer 124 in Adapalene gel?
To act as a surfactant
What is the role of Propylene glycol in Adapalene gel?
To act as a cosolvent
What is the primary function of Sodium hydroxide in Adapalene gel?
To adjust the pH of the gel
What is the primary function of Carbopol 980 in Adapalene gel?
To create a consistent texture
What is the role of Methylparaben in Adapalene gel?
To act as a preservative
What is the primary function of EDTA in Adapalene gel?
To chelate metal ions
What is the role of Poloxamer 124 in Adapalene gel?
To act as a surfactant
What is the primary function of Propylene glycol in Adapalene gel?
To act as a solvent
What is the primary function of Sodium hydroxide in Adapalene gel?
To adjust the pH
What is the primary function of a chelating agent like EDTA in a gel formulation?
To prevent oxidation of the active ingredients
What type of antioxidant is BHA?
Lipophilic antioxidant
What is the primary function of a hydrocarbon base in pastes?
To provide a stiff consistency
What is the primary function of preservatives in pastes?
To prevent the growth of microorganisms
What is the primary function of a surfactant in a gel formulation?
To reduce the surface tension of the formulation
What is the primary function of a gelling agent in a gel formulation?
To thicken the formulation and create a gel-like consistency
Study Notes
Pharmaceutical Pastes and Gels
- Pastes are semisolid dosage forms that contain a high percentage (often up to 50%) of finely dispersed solids.
- Characteristics of pastes:
- Stiff consistency
- Stay over the area to which they are applied
- Serve as protective coatings
- Used in the treatment of oozing lesions (absorb secretions)
Types of Pastes
- Single-phase aqueous paste
- Aqueous gel
- Triamcinolone acetonide dental paste (0.1%)
- Topical corticosteroid (oral lesions, mouth sores, decreases inflammation)
- Fatty paste
- Zinc oxide paste (16 - 40%) for diaper rash
- Contains Ricinus communis (castor) seed oil, Mineral oil, Paraffin, Balsam tolu resin, Petrolatum
Bases Used for Pastes
- Hydrocarbon base
- Soft paraffin and liquid paraffin
- Water miscible base
- Emulsifying ointment
- Plasticized hydrocarbon (PEG + hydrocarbons)
- Water soluble bases
- PEG bases
Preparation of Paste
- Fusion method
- Melt all bases & wax with continuous stirring
- Add powdered ingredients
- Continuous and constant stirring until cool
- Fusion and trituration method
- Melt the base
- Take powder (drug) and triturate with melted base (concentrate)
- Triturate (mix) the concentrate with the remaining base (heat may be used to facilitate mixing)
Commonly Used Excipients in Pastes
- Additional/alternative hydrophobic solvents
- Polydimethylsiloxane (liquid silicone)
- Vegetable oils (canola oil, sunflower oil, corn oil, soybean oil)
- Organic esters (isopropyl myristate)
- Preservatives (if necessary)
- Antioxidants
- Lipophilic antioxidants (BHA, BHT)
- Hydrophilic antioxidants (sodium metabisulfite)
Pharmaceutical Gels
- Gels are semisolid systems consisting of colloids as either:
- Small inorganic particles (colloidal suspension)
- Large organic molecules (interpenetrated by a liquid)
- Based on the external liquid phase, gels can be classified as:
- Polar/aqueous (hydrogels)
- Nonpolar/lipids (organogels)
Types of Gels
- Inorganic gels
- Aluminum hydroxide gel
- Bentonite magma colloidal dispersion
- Organic gels
- Polyacrylic acid polymers (Carbomer, Carbopol 980)
- Tragacanth
- Lecithin based
- Sorbitan ester based
Characteristics of Gels
- Swelling or Imbibition
- Taking up of water (or solvent) by the gel and increase in volume
- Syneresis or Weeping of Gel
- Opposite of swelling/imbibition
- Thixotropy
- Some gels turn into a sol on shaking and reset to the gel on standing
Excipients in Adapalene Gel
- Carbopol 980 (crosslinked polyacrylic acid)
- EDTA sodium
- Methylparaben
- Poloxamer 124 (Polyethylene-Polypropylene Glycol)
- Propylene glycol
- Purified water
- Sodium hydroxide
- Hydrochloric acid
Functions of Excipients in Adapalene Gel
- Gelling agent
- Chelating agent/Stabilizer
- Preservative
- Surfactant
- Cosolvent
- Solvent
Learn about pharmaceutical pastes and gels, including their types, formulation considerations, and patient counseling points. Understand the characteristics and properties of pastes and gels as semisolid dosage forms.
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