What practice ensures a homogeneous dispersion and uniform dose when preparing a suspension?

• A. Wetting the powder before putting into vehicle
• B. Increasing the particle size
• C. Adding more solute
• D. Heating the vehicle

Answer: (A)

Wetting the powder before adding it to the vehicle is essential because it lowers the interfacial tension between the solid particles and the liquid, allowing the liquid to penetrate and coat the particle surfaces. This breaks up agglomerates, reduces clumping, and creates a smoother, more uniform suspension where particles are evenly dispersed. When dispersion is uniform, each dose drawn from the suspension contains a similar amount of drug.

If you don’t wet the powder, particles tend to stick together and form aggregates that don’t distribute evenly, leading to variability in dosing as some portions are more concentrated than others. Using a small amount of solvent or a wetting/levigating agent helps achieve that initial smooth paste, which is then mixed into the final vehicle to maintain a stable, homogeneous suspension.

The other options don’t address dispersion effectively: increasing particle size makes settling and nonuniformity worse; adding more solute doesn’t improve how the particles spread; heating the vehicle isn’t a reliable way to achieve uniform dispersion and can affect stability.