What must be done to a suspension before administration to ensure a uniform dose?

To ensure a uniform dose of a suspension before administration, shaking it well is essential. Suspensions are mixtures where solid particles are dispersed in a liquid, and over time these solid particles may settle at the bottom of the container due to gravity. If not properly mixed, administering a dose from a suspension that has settled can lead to inaccurate dosing, as the concentration of the active ingredient may vary significantly throughout the liquid.

When the suspension is shaken, the solid particles are re-dispersed evenly throughout the liquid, allowing for a consistent distribution of the medication. This ensures that each dose administered contains the intended amount of the active ingredient, providing effective treatment and minimizing the risk of under-dosing or overdosing.

The other options do not contribute to the proper mixing and homogeneity of a suspension. Heating or cooling a suspension could potentially alter its properties or consistency but will not ensure that the solid particles are evenly distributed. Allowing it to sit is likely to exacerbate the settling of particles, leading to a lack of uniformity in the dose. Thus, shaking the suspension is the most effective and appropriate method for achieving a consistent and accurate dose.