When medications are ordered for infants and children, the dosage of medication (g, mg, mcg, gr) based on the weight of the child must be considered as well as how much medication the child can receive per dose or day.

Although the physician or nurse practitioner orders the medications, the nurse must be aware of the safe dosage range for administration of medications. It is the responsibility of the nurse to check a nursing drug reference for the right dosage before administering a medication to a child to prevent medication errors.

When physicians or nurse practitioners order medications for critically ill patients, the patients must be closely monitored by the nurse for effectiveness of the medications. Often, the medications or intravenous (IV) fluids must be titrated for effectiveness, with an increase or decrease in the dosage based on the patient’s response.

Factors involved in the safe administration of medications or IV fluids for the critically ill patient include the dosage of medication based on the weight of the patient and the time required for administration. The medication may need reconstitution or preparation by the nurse for immediate administration in a critical situation. The weight of the patient also may need to be obtained daily to ensure accurate correlation with the dosage of medication ordered. A nursing drug reference provides the nurse with information related to dosage, weight, and time for safe administration of medication.

To be able to calculate three-factor–given quantity to one-factor–, two-factor–, or three-factor–wanted quantity medication problems, it is necessary to understand all of the components of the medication order and to be able to calculate medication problems in a critical situation. This chapter will teach you to calculate medication problems involving the dosage of medication based on the weight of the patient and the time required for safe administration using dimensional analysis.