Podcast
Questions and Answers
What is primarily measured to assess the physical stability of a suspension?
What is primarily measured to assess the physical stability of a suspension?
What is the effect of centrifugation on a flocculated system?
What is the effect of centrifugation on a flocculated system?
In assessing rheological properties, what should be done to avoid destroying the suspension's structure?
In assessing rheological properties, what should be done to avoid destroying the suspension's structure?
What do the terms flocculation and deflocculation refer to in suspension stability?
What do the terms flocculation and deflocculation refer to in suspension stability?
Signup and view all the answers
To combine the results from sedimentation techniques and rheological assessments, what is necessary?
To combine the results from sedimentation techniques and rheological assessments, what is necessary?
Signup and view all the answers
Which parameter indicates that sedimentation has ceased?
Which parameter indicates that sedimentation has ceased?
Signup and view all the answers
What is a suitable mixer for creating a concentrated suspension?
What is a suitable mixer for creating a concentrated suspension?
Signup and view all the answers
What information can centrifugation provide despite its potential to destroy the flocculated structure?
What information can centrifugation provide despite its potential to destroy the flocculated structure?
Signup and view all the answers
What is the primary reason for finely subdividing drug particles before formulating a suspension?
What is the primary reason for finely subdividing drug particles before formulating a suspension?
Signup and view all the answers
What is a common effect of having particles greater than 25µm in diameter in a parenteral suspension?
What is a common effect of having particles greater than 25µm in diameter in a parenteral suspension?
Signup and view all the answers
Which of the following is true regarding wetting agents in formulations?
Which of the following is true regarding wetting agents in formulations?
Signup and view all the answers
In the context of suspensions, what is the difference between flocculated and deflocculated systems?
In the context of suspensions, what is the difference between flocculated and deflocculated systems?
Signup and view all the answers
What role do viscosity modifiers play in the formulation of suspensions?
What role do viscosity modifiers play in the formulation of suspensions?
Signup and view all the answers
Which of the following factors can lead to the growth of crystals in a suspension during storage?
Which of the following factors can lead to the growth of crystals in a suspension during storage?
Signup and view all the answers
What is the primary purpose of using wetting agents in suspension formulations?
What is the primary purpose of using wetting agents in suspension formulations?
Signup and view all the answers
How does particle shape affect the ease of administration for parenteral suspensions?
How does particle shape affect the ease of administration for parenteral suspensions?
Signup and view all the answers
Which thickening agent is suitable for maintaining a stable viscosity at both high and low pH levels?
Which thickening agent is suitable for maintaining a stable viscosity at both high and low pH levels?
Signup and view all the answers
Which factor is crucial for ensuring adequate bioavailability in the manufacture of suspensions?
Which factor is crucial for ensuring adequate bioavailability in the manufacture of suspensions?
Signup and view all the answers
What is the primary function of wetting agents in the preparation of suspensions?
What is the primary function of wetting agents in the preparation of suspensions?
Signup and view all the answers
How does sodium carboxymethylcellulose behave in the presence of polyvalent cations?
How does sodium carboxymethylcellulose behave in the presence of polyvalent cations?
Signup and view all the answers
What is a characteristic property of hydrated silicates used in suspensions?
What is a characteristic property of hydrated silicates used in suspensions?
Signup and view all the answers
In the context of suspensions, what is the main difference between flocculation and deflocculation?
In the context of suspensions, what is the main difference between flocculation and deflocculation?
Signup and view all the answers
Which of the following is NOT typically considered a formulation additive in suspensions?
Which of the following is NOT typically considered a formulation additive in suspensions?
Signup and view all the answers
What is the preferred concentration of sodium carboxymethylcellulose recommended for use?
What is the preferred concentration of sodium carboxymethylcellulose recommended for use?
Signup and view all the answers
Study Notes
Suspensions
- Finely divided insoluble solid particles dispersed in a fluid (dispersion medium)
- Particle size classifications dictate different types of solutions (true solution, colloidal solution, suspension)
- True solutions have particles < 10⁻⁷ cm
- Colloidal solutions have particles between 10⁻⁷ cm and 10⁻⁵ cm
- Suspensions have particles > 10⁻⁵ cm
Physical Properties of Well-Formulated Suspensions
- Remains homogeneous after shaking and removal of the dose
- Resuspension occurs easily with mild shaking
- No hard cake formation during shelf life, and easily redisperses
- Maintains stability and elegance during shelf life
Parenteral Suspensions
- Free from microbial contamination and must maintain sterility
- Easily drawn into a syringe and injectable
Pharmaceutical Applications of Suspensions
- Used when solid drug swallowing is difficult
- Used when drug solubility in an aqueous medium is poor (e.g., hydrocortisone, neomycin)
- This approach is particularly beneficial in pharmaceutical formulations where certain active ingredients are prone to hydrolysis or other chemical degradation when exposed to water. By creating an insoluble derivative, these drugs can be effectively delivered in a form that preserves their potency, stability, and therapeutic efficacy, while also facilitating their administration in a convenient suspension form.
Stability
- The product exhibits stability for 7 days when stored at room temperature, which typically ranges from 20°C to 25°C (68°F to 77°F). This duration allows for flexibility in handling and transportation before any deterioration occurs.
- When refrigerated, with a temperature set between 2°C and 8°C (36°F and 46°F), it maintains stability for up to 14 days, ensuring its efficacy and quality over a longer period, particularly useful for storage and usage in laboratory settings.
Additional Applications of Suspensions
- Used for vaccines to build up antibodies
- Utilized as X-ray contrast media, enhancing the visibility of internal structures during imaging procedures. (e.g., Barium sulphate)
- Used in aerosols
Formulation of Suspensions - Overview
- Particle Size Control: Finely dividing the drug decreases sedimentation rate, reduces gritty texture of large particles and potential eye irritation from large particles
- Wetting Agents: Wetting agents, also known as surfactants, play a crucial role in various applications by facilitating the interaction between water and insoluble solids. While some solids can be readily wetted and dispersed in water, others may resist wetting due to their hydrophobic properties. The degree of hydrophobicity can significantly vary among different materials. To achieve effective wetting, it is essential to decrease interfacial tension, thus enhancing the spreading and penetration of the liquid over the solid surfaces.
-
Flocculation/Deflocculation:
- Deflocculated: Particles exist as discrete units, slow sedimentation, sediment compaction. Pleasant appearance, slow settling and A cloudy supernatant indicates the presence of suspended particles. This turbidity often arises when solid particles are not completely settled at the bottom of a container, thus remaining in the liquid phase after centrifugation or sedimentation.
- Flocculated: Particles form loose aggregates, rapid sedimentation, easily redispersable sediment, no hard sediment cake. Unsightly, rapid sedimentation, clear supernatant
- Degree of Flocculation: Correct degree is crucial, under-flocculation is undesirable, over-flocculation is irreversible and can lead to inelegant appearance, high viscosity, and difficulties with redispersion.
- Rheology of Suspensions: High apparent viscosity at low shear rates for slow settling and good suspension, decreasing viscosity at high shear rates for easy pouring
- Viscosity Modifiers:
- polysaccharides (Acacia gum, tragacanth, alginates),
- water-soluble cellulose (methylcellulose, hydroxypropylcellulose, sodium carboxymethylcellulose),
- hydrated silicates (bentonite), colloidal silicone dioxide
- Other Formulation Additives: Buffers which maintain chemical stability, density modifiers which ensure sedimentation consistency, flavours, colorants, perfumes, humectants (glycerol, propylene glycol), preservatives, and sweetening agents
Manufacture of Suspensions
- Small scale*: This process combines a powdered drug, a suspending agent for uniform dispersion, and a liquid vehicle. A mortar and pestle ensure thorough mixing for consistent formulations and accurate dosing.*
- Large scale: Concentrated dispersion of suspending agent is prepared first, then slowly added to the vehicle while mixing. Appropriate mixing equipment like impeller blenders or turbine mixers
Stability Testing of Suspensions
- Physical Stability: This concept is critical in understanding the behavior of colloidal systems and dispersions. It can be quantitatively assessed through various parameters including the sedimentation rate, which indicates how quickly particles settle under gravity. Additionally, final volume or height of sediment provides insights into the concentration and stability of the dispersion over time. The ease of redispersion, evaluated through the V/Vo ratio compared over a specified timeline, assesses the ability of the sediment to return to a dispersed state after settling.
- Centrifugation: Useful for accelerating sedimentation rate, and provides relative stability information, but can potentially destroy flocculate structure.
- Rheological Assessment: Used to measure viscosity at various shear rates and provide insights into the structural changes that occur during storage; useful for routine quality control measures
- Temperature Cycling: Helps assess the stability against temperature fluctuations through cycling between high and low temperatures. Useful for assessing crystal growth, by measuring particle size for example.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Related Documents
Description
Explore the key concepts and physical properties of pharmaceutical suspensions. This quiz covers the definitions, classifications based on particle size, and unique applications in the parenteral context. Test your knowledge on the importance of stability and sterility in drug formulations.
