Determination of sedimentation volume with the effect of different suspending agents
BP407P Physical Pharmaceutics II Practical
AIM:
To determine the sedimentation volume with the effect of the different suspending agents.
PRINCIPLE:
SUSPENSION
Pharmaceutical suspension may be defined as a coarse dispersion in which insoluble solids are suspended in a liquid medium. It is also known as a heterogeneous system (or) more precisely biphasic system. The insoluble solids may have a size range from 10-10000µm and the liquid medium is normally water or a water-based vehicle.
SUSPENDING AGENT
Suspending agent is defined as a physiologically inert substance that increases its viscosity when added to suspensions. It helps in keeping the dispersed particles. Suspended thus there enhanced the physical stability and re-dispersion of the sediment or shaking.
PHYSICAL STABILITY
Physical stability may be defined as a condition in which particles remain uniformly distributed throughout the dispersion with any signs of sedimentation. In practice, Physical stability may be defined as a condition in which particles should be easily re-suspended by moderate shaking. If they settle suspensions when kept aside. The solids tend to settle at the bottom of the container due to gravitational pull on the particles of higher size. It is not possible to prevent the sedimentation volume and its case of re-dispersion is the common evaluation procedure for assessing the physical stability. The two sedimentation parameters are employed such as
- Sedimentation volume
- Degree of flocculation
SEDIMENTATION VOLUME:
• When a suspension is taken in a measuring cylinder volume and height is proportional and height can be conveniently measured through the term volume is included in the terminology sedimentation volume “F” is a dimensionless number. Most pharmaceutical suspension has an “F” value of less than one. If f=1 the product has no sediment and no clear supernatant on standing which is an ideal condition. Normally “F” value lies between 0 and 1. Sometimes the network of flow is loose and fluffy and the ultimate volume of sediment increases. In this situation, the “F” value will be greater than one.
PROCEDURE:
- Weigh 5gm of calcium carbonate and place it in a mortar and add a small quantity of water and triturate the sample. After suspending the powder uniformly transfer the suspension into a 100ml measuring cylinder to make up the volume to 100ml with distilled water.
- Separately prepare 5% w/v of calcium carbonate suspension with 1% of a different suspending agent such as bentonite, and methylcellulose, respectively in a different vessel add a small quantity of water, and triturate well. After the powder is uniformly suspended transfer the suspension into a separate 100ml measuring cylinder.
- Makeup the volume to 100ml with distilled water
- Shake the suspension simultaneously and kept aside
- Note the volume of sediment at time periods of 0,10,20,30,…60 minutes. Calculate the
sedimentation volume - Draw the plot by taking “F” values on the “Y” axis and the time on the “X” axis.
REPORT:
5% calcium carbonate suspension and 1% carboxy methyl cellulose as suspending was found to be more physically stable compared with other suspending agents.
Physical Pharmaceutics II Practical
- Determination of particle size, and particle size distribution using the sieving method
- Determination of particle size, and particle size distribution using the Microscopic method
- Determination of bulk density, true density and porosity
- Determine the angle of repose and the influence of lubricant on the angle of repose
- Determination of viscosity of liquid using Ostwald’s viscometer
- Determination of sedimentation volume with the effect of different suspending agent
- Determination of sedimentation volume with the effect of different concentrations of single suspending agent
- Determination of viscosity of semisolid by using Brookfield viscometer
- Determination of reaction rate constant first order.
- Determination of reaction rate constant second order
- Accelerated stability studies
Frequently asked questions (FAQs)
Sedimentation volume refers to the volume occupied by the sediment (settled particles) in a suspension after a specific period of time. It is a crucial parameter in pharmaceutical analysis as it helps assess the physical stability, settling behavior, and effectiveness of suspending agents in pharmaceutical formulations.
Sedimentation volume is determined by allowing a suspension to stand undisturbed for a defined time, usually 1 hour. The volume of the settled sediment is measured, and the sedimentation volume is calculated using the formula: Sedimentation Volume (%) = (Volume of Sediment / Total Volume of Suspension) × 100.
Suspending agents are substances added to pharmaceutical suspensions to prevent the settling of solid particles over time. They help maintain uniform distribution and improve the physical stability of the formulation, ensuring consistent dosing.
Different suspending agents have varying abilities to resist sedimentation due to differences in their viscosity, particle interaction, and molecular structure. Some agents, like natural gums (e.g., tragacanth), cellulose derivatives (e.g., carboxymethylcellulose), and synthetic polymers (e.g., polyvinylpyrrolidone), can significantly reduce sedimentation volume by increasing suspension viscosity and hinder particle settling.
The choice of suspending agent depends on factors such as the nature of the drug, desired viscosity, ease of preparation, patient acceptance, and compatibility with other formulation components. It is essential to select an agent that effectively maintains uniform suspension without compromising other aspects of the formulation.
To evaluate the effect of different suspending agents on sedimentation volume, pharmaceutical scientists prepare multiple suspensions of the same drug at the same concentration, each with a different suspending agent. These suspensions are allowed to stand, and sedimentation volumes are measured and compared to assess the ability of each agent to resist settling.
High sedimentation volume indicates poor physical stability and particle settling in the suspension. This can lead to inconsistent dosing, reduced therapeutic efficacy, and potential safety concerns if the active ingredient is not evenly distributed.
Yes, sedimentation volume can also be influenced by factors like particle size, particle concentration, pH, and the presence of electrolytes. Optimal formulation design considers a combination of suspending agents and other factors to achieve the desired physical stability.
The sedimentation volume test provides valuable insight into the initial stability and performance of a pharmaceutical suspension. However, real-world conditions, such as transportation, storage, and patient use, can impact the long-term stability and sedimentation behavior of the formulation.
Sedimentation volume testing is an essential quality control parameter for pharmaceutical suspensions. Regulatory authorities often require such testing to ensure that formulations maintain uniformity and deliver the intended dose over the product’s shelf life.
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