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There are suspensions that can be either flocculated or deflocculated. The main difference between flocculated and deflocculated suspension is that the rate of sedimentation in a flocculated suspension is rapid whereas the rate of sedimentation in a deflocculated suspension is slow.
Which type of suspension have relatively greater bioavailability?
h/mL) were significantly greater compared with fasting (p < 0.0001). Conclusions: This study has shown that the new atovaquone oral suspension also has significantly greater bioavailability when administered after food or a nutrition supplement that has a moderate fat content.
What is Deflocculated suspension?
A deflocculated suspension is a suspension in which no flocculation has taken place. Hence, there are no floccules or other aggregates. Here, single colloid particles act as individual particles. When sedimentation occurs, these single particles settle.
How Deflocculation is different from flocculation?
The key difference between flocculation and deflocculation is that flocculation is the formation of flocs by the clumping of fine particles, whereas deflocculation is the dispersion of flocs to form a stable colloid. Flocculation refers to the formation of clumps from fine particles in a colloid.
What does Deflocculated mean?
: to reduce or break up from a flocculent state : convert into very fine particles : disperse or maintain in a dispersed state.
What increases drug bioavailability?
The main mechanisms that have been identified through which bioenhancers can improve the bioavailability of drug molecules include alteration of the plasma membrane fluidity to increase passive transcellular drug permeation; modulation of tight junctions to allow for increased paracellular diffusion; and active efflux Jan 16, 2019
How do you increase suspension stability?
There are some useful methods to improve the physical stability of a suspension, such as decreasing the salt concentration, addition of additives to regulate the osmolarity, as well as changes in excipient concentrations, unit operations in the process, origin and synthesis of the drug substance, polymorphic behavior
What does poor oral bioavailability mean?
Oral bioavailability (F%) is the fraction of an oral administered drug that reaches systemic circulation. A poor oral bioavailability can result in low efficacy and higher inter-individual variability and therefore can lead to unpredictable response to a drug.
Why do Flocculated particles not cake?
Repulsive forces between particles are overcome and a hard cake is formed which is difficult, if not impossible, to redisperse. The sediment is loosely packed and possesses a scaffold-like structure (large volume of final sediment). Particles do not bond tightly to each other and a hard, dense cake does not form.
How is sedimentation rate of suspension measured?
Sedimentation of a suspension is generally assessed by a jar test, during which a suspension is allowed to settle and the height of the clear liquid (supernatant)-suspension interface is measured as a function of the settling time.
Which suspension is more stable and why?
Suspension is more stable. This is because suspension does not mix with each other. The denser particles settle down at the bottom and makes the solution stable.
Which type of suspension shows high rate of sedimentation?
8.3 for calcium carbonate suspensions relate to this type of sedimentation. When the solids concentration is very high, the maximum settling rate is not immediately reached and thus, may increase with the increasing initial height of suspension.
Which form of drug has highest bioavailability?
Thus having the highest bioavailability. Tablets take time to disintegrate. The order of decreasing bioavailability will be, solutions > emulsions > suspensions > capsules > tablets > coated tablets > enteric coated tablets>sustained released products. 4.
What are the features of flocculated suspension?
INTRODUCTION
| Flocculated suspension | Deflocculated suspension |
|---|---|
| The rate of sedimentation is high. | The rate of sedimentation is slow. |
| Sediment is easy to re-disperse. | Sediment is difficult to re-disperse. |
| Sediment is loosely packed and does not form a hard cake. | Sediment is tightly packed and forms a hard cake. |
What are the disadvantages of Unflocculated system?
However, a major disadvantage of this technique are the operational costs. In some cases, considerable quantities of coagulant and flocculant are needed to achieve the required level of flocculation. A certain quantity of physico-chemical sludge is also formed, which is normally processed externally.
How does temperature affect sedimentation?
The rate of sedimentation typically doubles for a 20°C rise in temperature. At higher temperatures (>50°C), sedimentation becomes difficult. This is due to increase in solubility of the carbonates.
Why are suspending agents used?
2. SUSPENDING AGENTS Suspending agents also called thickening agents are used to stabilize suspensions are hydrophilic colloid i.e. substances that spontaneously form colloidal dispersions with water because of an affinity between the dispersed particles and the dispersion medium.
What are the desirable properties of a good suspension?
Desirable properties of suspensions are that they should have good organoleptic properties, suspensions should possess good pourability leading to ease of removal of dose from container, the particle size distribution should be uniform, there should be ease of re dispersion of settled solid particles, they should be Dec 8, 2015
Why is flocculated suspension better?
There are suspensions that can be either flocculated or deflocculated. The main difference between flocculated and deflocculated suspension is that the rate of sedimentation in a flocculated suspension is rapid whereas the rate of sedimentation in a deflocculated suspension is slow.
How can you prevent suspension from sedimentation?
Slow down sedimentation by increasing viscosity of continuous phase. Velocity increases with the square of particle size making this the most critical parameter. For concentrated systems a crowding factor must be introduced which incorporates the phase volume Φ.
What are the suspending agent?
: a substance (such as carrageenan, xanthan gum, or cellulose ether) that is added to fluids to promote particle suspension or dispersion and reduce sedimentation All these drinks can contain preservatives, and drinks other than juices can contain additives to colour, flavour and sweeten.
Is Redisperse difficult?
The repulsive forces between individual particles allow them to slip past each other as they sediment. The slow rate of settling prevents the entrapment of liquid within the sediment, which thus becomes compacted and can be very difficult to redisperse.
What is needed for good bioavailability?
The most reliable measure of a drug’s bioavailability is AUC. AUC is directly proportional to the total amount of unchanged drug that reaches systemic circulation. Drug products may be considered bioequivalent in extent and rate of absorption if their plasma concentration curves are essentially superimposable.
Is sedimentation good for suspension?
Stokes developed an equation which relates the rate of sedimentation to the physical properties of the suspension. Therefore, a second important function for suspending agents is to facilitate redistribution of a suspension on shaking. Particles in suspension can come together to form either floccules or aggregates.
Which is the best suspending agent?
The most common suspending agents are aqueous biological polymers, including methylcellulose (MC), sodium carboxymethylcellulose (CMC), and hydroxypropylmethylcellulose (HPMC). A range of viscosities of suspending agents is available with different molecular weights.
