The elimination rate constant of ibuprofen is 0.1155/hr and its volumeof distribution is 0.17 L/kg. What will be the dosing regimen requiredfor a 70-kg man to achieve an average plasma concentration of 50mg/L at steady state (bioavailability is 100%)a. 100 mg every 8 hoursb. 300 mg every 12 hoursc. 500 mg every 8 hoursd. 400 mg every 6 hours

To solve this problem, we need to use the formula for the maintenance dose rate (MDR) at steady state, which is:

MDR = (Desired plasma concentration * Volume of distribution * Elimination rate constant * Weight) / Bioavailability

Given that the desired plasma concentration is 50 mg/L, the volume of distribution is 0.17 L/kg, the elimination rate constant is 0.1155/hr, the weight is 70 kg, and the bioavailability is 100% (or 1), we can substitute these values into the formula:

MDR = (50 mg/L * 0.17 L/kg * 0.1155/hr * 70 kg) / 1 MDR = 68.485 mg/hr

This is the amount of ibuprofen that needs to be administered per hour to maintain the desired plasma concentration. Now we need to convert this to a dosing regimen.

Let's check each option:

a. 100 mg every 8 hours = 100 mg / 8 hr = 12.5 mg/hr b. 300 mg every 12 hours = 300 mg / 12 hr = 25 mg/hr c. 500 mg every 8 hours = 500 mg / 8 hr = 62.5 mg/hr d. 400 mg every 6 hours = 400 mg / 6 hr = 66.67 mg/hr

The closest option to our calculated MDR of 68.485 mg/hr is option d. 400 mg every 6 hours. Therefore, the dosing regimen required for a 70-kg man to achieve an average plasma concentration of 50 mg/L at steady state with a bioavailability of 100% is 400 mg every 6 hours.