<P> The therapeutic window (or pharmaceutical window) of a drug is the range of drug dosages which can treat disease effectively without having toxic effects . Medication with a small therapeutic window must be administered with care and control, frequently measuring blood concentration of the drug, to avoid harm . Medications with narrow therapeutic windows include digoxin, lithium, and warfarin . </P> <P> Optimal biological dose (OBD) is the quantity of a drug that will most effectively produce the desired effect while remaining in the range of acceptable toxicity . </P> <P> The maximum tolerated dose (MTD) refers to the highest dose of a radiological or pharmacological treatment that will produce the desired effect without unacceptable toxicity . The purpose of administering MTD is to determine whether long - term exposure to a chemical might lead to unacceptable adverse health effects in a population, when the level of exposure is not sufficient to cause premature mortality due to short - term toxic effects . The maximum dose is used, rather than a lower dose, to reduce the number of test subjects (and, among other things, the cost of testing), to detect an effect that might occur only rarely . This type of analysis is also used in establishing chemical residue tolerances in foods . Maximum tolerated dose studies are also done in clinical trials . </P> <P> MTD is an essential aspect of a drug's profile . All modern healthcare systems dictate a maximum safe dose for each drug, and generally have numerous safeguards (e.g. insurance quantity limits and government - enforced maximum quantity / time - frame limits) to prevent the prescription and dispensing of quantities exceeding the highest dosage which has been demonstrated to be safe for members of the general patient population . </P>

Are narrow spectrum drugs the same as narrow therapeutic index drugs