Suspension Lecture Notes

These flashcards cover key concepts and details from the lecture on suspensions, including definitions, equations, and important considerations in pharmaceutical formulations.

What is a suspension?

A 2-phase system consisting of a finely divided solid dispersed in a liquid.

What factors affect the stability of a suspension?

Uniform dispersion, slow to settle, readily redispersed, constant particle size over time, and easy to pour and administer.

What equation is used to analyze the rate of sedimentation in suspensions?

Stoke's Equation.

What are the desired features for a suspension?

Uniform dispersion, slow to settle, readily redispersed, constant particle size, easy to pour.

Why are suspensions used instead of solutions for some drugs?

Certain drugs are chemically unstable in solutions but stable when suspended.

How does particle size affect sedimentation rate?

Decreasing particle size exponentially decreases the rate of settling.

What is Stokes' equation used for?

To calculate the rate of settling of particles in a suspension.

What is the ideal particle size range for good pharmaceutical suspensions?

1-50 μm.

What is the impact of viscosity on sedimentation rate?

The rate of settling is inversely proportional to viscosity.

What is flocculation in suspensions?

The formation of weakly bound aggregates of particles that settle rapidly without caking.

What is coagulation in suspensions?

A process where particles irreversibly aggregate after overcoming energy barriers, making separation difficult.

Name a common thickening agent used in suspensions.

Carboxymethylcellulose (CMC).

What is levigation?

The process of wetting, separating, and reducing particle size before suspension.

What does a flocculated suspension do?

It settles quickly in a lattice structure, is easy to redisperse, and avoids caking.

What is the role of wetting agents in suspensions?

To displace air and allow the dispersion medium to penetrate the powder.

Define DLVO theory.

A theory describing the interaction forces between charged surfaces through a liquid medium.

What is the significance of Archimedes' principle in relation to suspensions?

It helps to understand the behavior of suspended particles in a fluid.

Give an example of a pharmaceutical suspension.

Oral suspension of an antibiotic.

What happens if the density of suspended particles and the suspending medium are equal?

Settling should not occur.

What is the effect of increasing viscosity on the settling rate?

It reduces the settling rate.

What are the main components of a dry powder for oral suspension?

Antibiotic drug, colorants, flavorants, sweeteners, stabilizing agents, and suspending agents.

Why should suspensions be shaken before use?

To ensure uniform distribution of solid in the vehicle and proper dosage.

What are common wetting agents for aqueous suspensions?

Water, alcohol, glycerin, and propylene glycol.

How can particle shape affect suspension stability?

Symmetrical shapes are more stable, while asymmetrical shapes can lead to caking.

What is the purpose of suspending agents?

To slow down the settling process and ensure consistency.

What precaution should be taken with extemporaneous compounded suspensions for infants?

Avoid preservatives and alcohol.

What is the primary function of a emulsifying agent in a suspension?

To stabilize the dispersion and prevent agglomeration.

Why should some suspensions be stored in light-resistant containers?

To prevent degradation from light exposure.

Explain the importance of airspace in packaging suspensions.

To allow room for mixing, shaking, and pouring.

What is the significance of using a colloid mill in suspension preparation?

To achieve even particle size and ensure uniform suspension.

What is the effect of shaking a suspension before use?

It redistributes the solid particles evenly throughout the liquid.

How does the preparation of suspensions differ for oral vs. parenteral use?

Parenteral suspensions require sterile conditions and may have different viscosity requirements.

What is floccule formation's advantage in suspensions?

It helps in quick redispersement and prevents caking.

How does particle size reduction affect stability?

Smaller particles lead to reduced sedimentation rates and increased stability.

What are the key considerations in the selection of flavorants for suspensions?

Taste masking and stability in the product formulation.

Why might infants and the elderly require special considerations for oral medications?

They may have specific physiologic differences, making administration more complex.

How does Stoke's law apply in the pharmaceutical field?

It helps predict the behavior of drug particles in suspension formulations.

Describe the impact of temperature on suspensions.

Temperature can affect viscosity and solubility, impacting suspension stability.

What influences the choice of a suspending agent?

The nature of the drug, desired viscosity, and administration route.

What should patients be instructed regarding the storage of compounded suspensions?

Store in an airtight container and refrigerate.

What are the consequences of inadequate mixing of a suspension?

Uneven dosing and possible therapeutic failure.

What is the function of preservatives in suspensions?

To prevent microbial contamination.

How is particle size typically reduced prior to suspension preparation?

By dry milling or micropulverization.

Describe the buccal administration of suspensions.

Suspensions can be administered in forms suitable for absorption through oral mucosa.

What precautions are necessary when compounding drugs for elderly patients?

Minimize risks of drug interactions and side effects.

What method can be employed to prevent agglomeration in suspensions?

Utilizing flocculating agents to maintain separation of particles.

What is the role of the pharmacist in extemporaneous compounding?

To ensure the preparation is stable, effective, and safe for the patient.

How can sedimentation volume (F) be calculated?

F = Vu / Vo, where Vu is the final volume of sediment and Vo is the original volume.

Explain the significance of caking in suspensions.

Caking makes it difficult to redisperse settled particles, affecting dosing accuracy.

What are the benefits of using an anti-caking agent in formulations?

To maintain free-flowing particles and prevent clumping.

What is the purpose of flavoring agents in oral suspensions?

To improve palatability for patient compliance.

What factors should inform the choice of suspension vehicle?

Viscosity, stability, solubility of the drug, and patient acceptability.

How important is the particle distribution in achieving suspension stability?

Uniform particle distribution is critical for preventing caking and ensuring availability.

What types of medications are typically presented as topical suspensions?

Protectives, antipruritic agents, antibacterial preparations.

What measures should be taken for a stable suspension formulation?

Ensure appropriate viscosity, homogeneity, and absence of caking.

Identify a complication that may arise from improper extemporaneous compounding.

Inaccurate dosing and potential therapeutic failure.

Outline the procedure for preparing a suspension from a dry powder.

Loosen powder, add water, shake to mix, and create homogenous suspension.

What characteristics dictate the effectiveness of a herbal suspension?

Proper dispersion, stability, and bioavailability of active ingredients.

In what circumstances is it crucial to consult pharmaceutical literature?

For stability and formulation information of compounded drugs.

What guideline must be followed for patient safety with suspensions?

Ensure clear instructions for storage, shaking, and dosing to maintain efficacy.

What regulatory considerations can affect the compounding of suspensions?

Compliance with pharmaceutical regulations regarding safety and effectiveness.

What criteria are used to evaluate the quality of a suspension?

Stability, appearance, viscosity, and ease of dispersibility.

What potential issues can arise from the incorrect choice of a suspending agent?

Improper viscosity could lead to settling, clumping, or ineffective dosing.

Summarize how temperature influences suspension preparation.

Temperature affects viscosity and solubility, altering mixing and stability.

Clarify the role of professional literature in suspension compounding.

To provide evidence-based information on formulation best practices.

What assessment is crucial when determining the effectiveness of flavored suspensions?

Patient satisfaction and compliance based on taste acceptance.

What recommendations should be provided for administering suspensions to pediatric patients?

Use appropriate dosing devices and monitor response to treatment.

What common factors contribute to the instability of suspensions?

Improper particle size, inadequate viscosity, or incorrect storage.

How does the stability of a drug in suspension compare to that in a solution?

Drugs may be more stable in suspension due to reduced solubility risks.

Why is knowledge of solid-state chemistry important in suspension formulation?

To understand drug behavior, interactions, and stability in the suspension matrix.

List some examples of drugs commonly found in topical suspensions.

Calamine lotion and hydrocortisone cream.

What is the goal of proper suspension formulation?

To provide stable, safe, and effective drug delivery.

Why is storage in an airtight container crucial for liquid suspensions?

To prevent contamination and maintain drug efficacy.

In compounding, what role does the concept of homogeneity play?

Homogeneity ensures that the dosage is consistent and effective across the suspension.

What do pharmaceutical manufacturers typically provide regarding prescriptive granules used in suspensions?

Information about stability and behavior in a liquid medium.