Question

1. An antibiotic is to be given after surgery at a dose of 20 mg/kg. If a 750 mL solution was prepared containing 10% w/v of the antibacterial agent, how many milliliters would be given to the patient if the patient weighed 175 pounds?

2. An antineoplastic agent is to be administered via IV injection for osteosarcoma at a dose of 250 mg/m2. In renally-impaired patients, however, the dose is to be reduced by 17.5% if the patient has a BSA below 1.80 m2, and by 20% if the BSA is above 1.80 m2. How many milligrams of drug should be administered to a patient who is 5'5 in height, who weighs 125 lb, and is renally impaired?

3. A patient is to undergo a cycle of chemotherapy for multiple myeloma. Drug X has a dose of 45 mg/m2/day and is to be given at D1-4 of the cycle, whereas Drug Y, with a dose of 8 mg/m2/day, is to be given at D1-4 & 9-12. For a patient who is 5'11 and is 201lb, calculate the total amount in mg that the patient will receive for both drugs within the cycle.

Answer 1

1. Antibiotic

dose of 20 mg/kg

750 mL solution containing 10% w/v was prepared

10% means 100ml contains 10g of substance

ie; 750ml contains 75g of substance

patient weighed 175 pounds = 79.4 kg

dose of 20 mg/kg, ie: total dose= 79.4×20 = 1588mg

10g = 100ml

1.588g = (100/10) × 1.588 = 15.88ml

2.

dose is 250 mg/m2.

5'5 in height, weight 125 lb

BSA = √((HEIGHT(CM) × WEIGHT (KG)) /3600)

Height - 5'5feet - 167.64cm

Weight - 125lbs - 56.7kg

BSA - √165.1×56.7÷3600

=√2.60= 1.61m2

renally-impaired patient, the dose is to be reduced by 17.5% patient has a BSA below 1.80 m2

17.5% = (17.5/100) × 250 = 43.75

Renal dose = 250 - 43.75 = 206.25mg/m2

1m2 - 206.25mg

1.61m2 - 206.25×1.61

- 332.06mg ~ 332 mg

3.

Drug X has a dose of 45 mg/m2/day and is to be given at D1-4 of the cycle

Drug Y, with a dose of 8 mg/m2/day, is to be given at D1-4 & 9-12

5'11 and is 201 lbs

BSA = √((HEIGHT(CM) × WEIGHT (KG)) /3600)

Height - 5'11feet - 180.34cm

Weight- 201lbs - 91.17

BSA = √(180.34×91.17) /3600=√4.6= 2.13m2

Drug X = 45 mg/m2/day, D1-4

Total dose = 45mg × 2.13m2 × 4days = 383.4 mg

Drug Y = 8 mg/m2/day, D1-4 & 9-12

Total dose = 8mg × 2.13m2 × 8days = 136.32 mg