Difference Between Solutions and Suspensions

Main difference

The main difference between solutions and suspensions is that a solution is a homogeneous mixture formed when two or more soluble chemical moieties dissolve in the dissolving medium, whereas suspensions are heterogeneous mixtures when finely divided solid moieties are dispersed in the dissolving medium. dispersion.

Solutions against suspensions

One solution is a one-phase system in which the solute completely dissolves in the vehicle; On the other hand, suspension is a two-phase system in which solid particles do not dissolve in the vehicle and remain uniformly suspended throughout the vehicle. Solutions are simple mixtures of solute and solvent while suspensions are mixtures of finely divided solid particles and a carrier that require a suspending agent to suspend the solid particles in the carrier. Solutions support water-soluble chemical fractions, while suspensions can support water-soluble and insoluble chemical fractions. In solutions, dissolved particles do not settle to the bottom of the container even if kept for a long period, for other side, in suspensions, the suspended particles settle to the bottom of the container if they remain for some time. There is no need to shake the container of solutions before use, whereas in case of suspensions, shaking of the container is the basic requirement before use to ensure uniform distribution of solid particles. Although solutions require preservatives, some solutions they do not require preservatives such as concentrated sugar solutions (syrups) and high content alcoholic solutions, while all suspensions require preservatives depending on the degradation pathway of the suspended solid particles. In solutions, the solubility of the solute can be improved by adjusting the pH, while the pH has no such role in suspensions. some solutions do not require preservatives such as concentrated sugar solutions (syrups) and high content alcoholic solutions, while all suspensions require preservatives based on the chemical degradation pathway of the suspended solid particles. In solutions, the solubility of the solute can be improve by adjusting the pH, whereas pH does not play such a role in suspensions. some solutions do not require preservatives such as concentrated sugar solutions (syrups) and high content alcoholic solutions, while all suspensions require preservatives depending on the chemical degradation pathway of the suspended solid particles. In solutions, the solubility of the solute can be improved by adjusting the pH, while the pH has no such role in suspensions.

Comparison chart
Solutions Suspensions
Solutions are liquid preparations. Suspensions are liquid semisolid preparations.
particle size
In solutions, the particle size of the solute is small compared to the size of the dispersed phase of suspension. In suspensions, the particle size of the disperse phase is larger than the particle size of the solution.
Appearance
The solutions are transparent in appearance. The suspensions have a cloudy appearance.
passage of light
Light can pass through solutions. Light cannot pass through suspensions.
Separation of components
Neither filtration nor any other separation technique can separate components from solutions. The suspension components can be easily separated by filtration and allowed to settle.
The capacity of dissolved and dispersed components.
The dissolved components of solutions take on the properties of the dissolution medium. The dispersed components of the suspensions do not take on the properties of the dispersion medium.
availability form
The solutions are “ready-to-use” preparations. Suspensions may be “ready-to-use” preparations or may be reconstituted at the time of use.
The requirement of dissolution and dispersion medium.
Solutions do not require any agent to dissolve the solute in the solvent. Suspensions require a suspending agent to suspend the dispersed phase in the dispersion medium.
Absorption rate
The absorption rate of solutions is high in any dosage form. The absorption rate of the suspension is low in any dosage form.
What are solutions?

Solutions are liquid preparations that are prepared by dissolving one or more active chemical moieties (solute) in a suitable solvent. The solute is the chemical moiety that dissolves while the solventis the vehicle in which the solute dissolves. The solvents used can be aqueous (water-based) or non-aqueous. Aqueous solvents are used because most chemical moieties are soluble in water. Co-solvents are sometimes used when water alone is not enough to dissolve chemical residues. Non-aqueous solvents are used when chemical moieties are not stable in water or dissolve in water. Solutions can be saturated or unsaturated depending on the solute concentration. If the solute concentration is below the solubility limit, then the solution is called an unsaturated solution, and if the solute concentration is above the solubility limit, then the solution is called a saturated solution.

Example

When sugar or salt dissolves in water, they form the sugar or salt solution.

What are suspensions?

A suspension is a liquid or semiliquid preparation prepared by the uniform dispersion of undissolved chemical moieties in a dispersion medium. The basic ingredients of suspensions are the drug, functional excipients, and the external environment. The main role of functional excipients is to wet the drug, influence flocculation, control viscosity and adjust pH. The other ingredients are flavoring agents, sweeteners, colors and preservatives. Without wetting agents (suspending agent), a suspension cannot be prepared as suspending agents do not allow the suspended particles to settle. Suspensions are pharmaceutically formulated to mask the bitter taste of the drug. In the suspensions

Example

An example of suspensions is paracetamol suspension.

Key differences

  1. Solutions are homogeneous mixtures, while suspensions are heterogeneous mixtures.
  2. Solutions are a monophasic system, on the other hand, suspensions are a biphasic system
  3. The particles do not settle in solutions since the components of the solutions are completely miscible while the particles settle in suspensions because the particles are suspended in the carrier.
  4. The concentration of the solutions is measured in w/v, v/v, v/w, but the concentration of the suspensions is measured in mg/ml.
  5. Solutions are effective for hydrophilic drugs, on the other hand, suspensions are effective for hydrophobic drugs.
  6. Chemical moieties that are not stable in water cannot be formulated as a solution. Chemical moieties that are unstable in water can be formulated as a suspension.

Final Thoughts

The conclusion from the above discussion is that solutions are simple preparations compared to suspensions. Suspensions are preferred when solutions may not be the best option to be formulated. From a pharmaceutical point of view, both are important because both have their own advantages as drug formulations.

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