Which practice is essential to prevent over or under medication?

The practice that is essential to prevent over or under medication is medication measurement. Accurate measurement of medications ensures that the correct dosage is administered to the patient. This is critical because even slight deviations in dosage can lead to adverse effects, either through an overdose or an ineffective dose if it's too low.

While accurate dosing is closely related to measurement, it encompasses the broader concept of determining how much of a medication a patient should receive based on various factors, including the specific condition being treated. However, without proper measurement practices, accurate dosing cannot be achieved consistently.

Valid medicinal practice and calibrated tools are also important components of safe medication administration but focus on different aspects. Valid medicinal practice pertains more to the overall quality and appropriateness of the medication being used, ensuring it is suitable for the patient's particular needs. Calibrated tools are important for ensuring that the measurement devices themselves are accurate, but they are only part of the larger picture if the actual measurement practices are not conducted correctly.

Overall, medication measurement as a practice lays the foundation for safe and effective medication administration.