The maximum safe daily dose of Drug X for adults is 1,500 mg. A prescription orders 20 mg/kg/day for a 70 kg adult. Is this within the safe daily limit?

• A. Yes; 1,400 mg/day
• B. No; 1,600 mg/day
• C. No; 2,250 mg/day
• D. Yes; 1,500 mg/day

Answer: (A)

To decide if the prescription is within the safe limit, convert the daily dose from mg/kg to mg per day and compare it to the maximum. Multiply 20 mg/kg/day by the patient’s weight: 20 × 70 = 1,400 mg per day. Since the maximum safe daily dose is 1,500 mg, 1,400 mg is below the limit, so it’s within the safe daily limit. The other numbers would exceed the limit (1,600 mg/day and 2,250 mg/day) or reflect a 1,500 mg/day dose for a different weight (75 kg) and don’t match this patient’s calculations.