If a client weighs 198 lb and requires vancomycin at a dosage of 15mg/kg/day, how much should be administered every 12 hours?

To determine the appropriate vancomycin dosage for a client weighing 198 lb, first, it is essential to convert the weight from pounds to kilograms. Since 1 kilogram is approximately 2.2 pounds, you can calculate the weight in kilograms by dividing the weight in pounds by 2.2:

198 lb ÷ 2.2 = 90 kg (approximately).

Next, the prescribed dosage is 15 mg/kg/day. To find the total daily dosage based on the client’s weight, multiply the weight in kilograms by the dosage:

90 kg × 15 mg/kg/day = 1350 mg/day.

Since the question specifies that the medication should be administered every 12 hours, you need to divide the total daily dosage by the number of doses per day. As there are 24 hours in a day and the dosage is given every 12 hours, there are 2 doses per day:

1350 mg/day ÷ 2 = 675 mg per dose.

Therefore, the correct administration amount every 12 hours for this client is 675 mg, making the answer B correct. This calculation ensures that the client receives the prescribed daily medication effectively and safely.