Which statement describes a drug with a low therapeutic index?

A drug with a low therapeutic index indicates that the range between the effective dose and the toxic dose is narrow. This means that even a slight change in dosage can lead to adverse effects or toxicity. In medications with a low therapeutic index, precision in dosing is essential, as the difference between a therapeutic dose and a harmful dose is minimal.

This characteristic necessitates careful management and consideration when prescribing such medications, as it directly influences the risk of toxicity. The other options, while related to therapeutic index characteristics, do not accurately describe a drug with a low therapeutic index. For instance, a wide margin of safety typically pertains to drugs with a high therapeutic index, and the notion of frequent monitoring may be relevant but does not inherently convey the critical aspect of dosage sensitivity that defines drugs with a low therapeutic index.