Suspensions appropriate for pediatric use are developed to ensure safety and consistency in drug administration. These formulations should be palatable, stable in the home environment, and easily measured by the caregiver. Suspensions for patient consumption use a limited palette of additives that are generally recognized as safe over a wide range of patient ages, disease states, and varying metabolic capacities. Desirable characteristics of a successful pediatric suspension include a pourable, uniform dose, which remains suspended up to 30 seconds after shaking. Every dose in the bottle must be identical during the open shelf-life of 30 days.

Formulating a colloidal dispersion of a finely-divided solid with additives that prevent rapid settling in an aqueous environment can illustrate several principles of physical chemistry in a classroom environment. Students are given colored sand, water, bottle, three 2% (w/w) USP methylcellulose solutions of different viscosities (400, 1500, and 4000 cps), and a 2% guar gum solution. Equipment available are a mortar and pestle, pipettes, and a stop-watch. Many students use trial and error to obtain the desired outcome, but some use recently-studied principles, e.g., particle size, decrease density between particle and liquid medium, and increase viscosity. Grinding the sand down to a fine powder is critical to the suspension. Most successful suspensions use a combination of all three methylcellulose solutions with little or no guar gum. This hands-on experiment was recently used to illustrate the complexity of developing pediatric suspensions to a group of Medical and Marketing Executives at a pharmaceutical company.