Interactions and incompatibilities between drugs and vehicles used in oral administration

The oral route is the most widely used for drug administration due to its convenience (ease, high safety). Water is the optimal vehicle (lack of interactions with drugs) currently used for the oral administration of drugs; however, sometimes other vehicles are used: liquids such as milk or fruit juices, or semisolid foods such as puddings, yogurts and others. This is often when there are difficulties on the part of patients, either because they do not like the taste of the medication (for example, children) or have dysphagia problems (older people). This may pose problems due to some components or characteristics of the food used that can interact with the drug, leading to a decrease in its bioavailability or an alteration of its pharmacological properties. Different parameters have to be taken into account when considering the suitability of a food as a vehicle for drug administration. When a drug is mixed with food, incompatibility could arise from problems of solubility, stability or homogeneity of the preparation, as well as the pH, viscosity or other properties of the food and the physicochemical characteristics of the drug. Problems of drug inefficacy derived from these interactions are increasing especially in older people, due to the problems they have in swallowing solid dose forms, which lead to the crushing of these forms and mixing with food. Sometimes little information is available about the presence of incompatibilities, and little indication is given to patients and caregivers about how to prevent these problems.