What is the formula for the maintenance dose (MD)?

The maintenance dose (MD) is a critical concept in pharmacology, particularly in ensuring that drug levels in the body remain within a therapeutic range. The formula for determining the maintenance dose is based on several pharmacokinetic parameters, specifically the desired concentration of the drug in the plasma (Cp), the clearance of the drug (CL), and the bioavailability (F) of that drug.

The correct formula is represented as MD = Cp x CL/F. Here’s how each component contributes to the calculation:

1. Cp: This refers to the target plasma concentration of the drug that you aim to achieve and maintain during treatment. Understanding the desired therapeutic concentration is essential for effective drug dosing.

2. CL (Clearance): This parameter indicates how efficiently the body can eliminate the drug from the plasma. A drug with a high clearance will require a higher maintenance dose to maintain the same plasma concentration compared to a drug with low clearance.

3. F (Bioavailability): This accounts for the fraction of the administered dose that actually reaches the systemic circulation. It is especially important for orally administered drugs, as not all of the drug may be absorbed or reach the bloodstream due to first-pass metabolism or other factors.

The formula is structured so that