Dosage Calculations in Nursing

• Dosage calculations are essential in nursing practice for accurate medication administration.

Dosage Problems and Solutions

• A provider prescribes 500 mg of amoxicillin, and the pharmacy provides 250 mg tablets; administer 2 tablets, calculated by dividing the prescribed dose (500 mg) by the available dose per tablet (250 mg).
• A patient is prescribed 750 mg of acetaminophen, with a liquid formulation of 160 mg per 5 mL; administer 25 mL, calculated by dividing the prescribed dose (750 mg) by the concentration (160 mg) and multiplying by the volume (5 mL).
• To administer 500 mL of IV fluid over 4 hours, the infusion rate should be 125 mL/hr, calculated by dividing the total volume (500 mL) by the time in hours (4 hours).
• For a child weighing 22 kg prescribed 10 mg/kg of medication, administer 220 mg, calculated by multiplying the weight (22 kg) by the dose (10 mg/kg).
• The maximum volume safely injected into the deltoid muscle for an adult is 1 mL; larger volumes should be injected into the ventrogluteal or vastus lateralis sites.
• For 40 units of insulin subcutaneously (SQ) from a vial labeled 100 units/mL, administer 0.4 mL, calculated by dividing the required units (40 units) by the concentration (100 units/mL).
• If a patient is prescribed 1.5 g of cefazolin IV and the pharmacy provides vials labeled 500 mg per vial, use 3 vials, calculated by converting grams to milligrams (1.5 g = 1500 mg) and dividing by the amount per vial (500 mg).
• If a patient drinks 8 oz of juice, 4 oz of coffee, and 6 oz of water, the total intake is 600 mL, calculated by converting ounces to mL (1 oz = 30 mL) and summing the volumes.
• To administer 100 mL of IV medication over 30 minutes, the infusion rate should be 200 mL/hr, calculated by dividing the volume (100 mL) by the time in hours (0.5 hours).
• A patient's output is 400 mL in the morning, 250 mL in the afternoon, and 300 mL in the evening; the total output is 1050 mL, calculated by adding all the amounts.