The level of drug between the minimum effective concentration and the minimum toxic concentration in the blood is known as the:

• A. Drug interval
• B. Therapeutic range
• C. Volume of distribution
• D. Bioavailability

Answer: (B)

The therapeutic range is the concentration window in the blood where a drug provides the desired therapeutic effect without causing appreciable toxicity. It lies between the minimum effective concentration, where the drug starts to work, and the minimum toxic concentration, where toxicity can occur. Keeping the drug’s level within this range maximizes benefit and minimizes harm. This differs from other pharmacokinetic terms: the dosing interval refers to how often you give the dose, volume of distribution describes how the drug disperses in body compartments, and bioavailability describes how much of the administered dose reaches systemic circulation.