Final answer:
To achieve the desired AUC:MIC ratio of 400 mg/L x hr with a clearance of 2.5 L/hr for vancomycin, the required dose is calculated to be 1000 mg. None of the provided options match this calculated dose with precision, but the closest standardized dose that does not fall below the therapeutic range is 1500 mg.
Step-by-step explanation:
To calculate the required dose of vancomycin to achieve the desired AUC:MIC ratio of 400 mg/L x hr, we can use the formula AUC = Dose / Clearance (CL), where AUC represents the area under the concentration-time curve, and Clearance is the rate at which a drug is eliminated from the body. Given the desired AUC:MIC of 400 mg/L x hr and the vancomycin clearance of 2.5 L/hr, we can rearrange the formula to solve for the dose:
Dose = AUC x CL
By substituting the given values:
Dose = 400 mg/L x hr x 2.5 L/hr
The dose required to achieve the desired AUC:MIC ratio would be:
Dose = 1000 mg
Therefore, none of the options (A) 1500 mg, (B) 800 mg, (C) 500 mg, or (D) 320 mg exactly match the calculated dose of 1000 mg. However, usually one would have to pick the closest available standardized dosage form, and given the options, the correct choice would generally be the one closest to 1000 mg without going under the required therapeutic range, which would be (A) 1500 mg.
It's important to consider that in an actual clinical scenario, the dosing may also be influenced by other factors such as the drug's half-life, patient's weight, kidney function, the severity of infection, and the potential for drug-drug interactions (DDI).