What does a narrow therapeutic index imply about a medication?

A narrow therapeutic index indicates that there is a small range between the effective dose and the toxic dose of a medication. This means that slight changes in the dose, absorption, or metabolism of the drug can lead to significant changes in its effects—potentially causing toxicity if the dose is too high, or ineffectiveness if the dose is too low. Because of this limited margin for safety, medications with a narrow therapeutic index require careful monitoring of blood levels, patient response, and any adverse effects.

This careful monitoring is crucial to ensure that patients remain within the therapeutic range, minimizing the risk of complications associated with drug toxicity or inadequate therapeutic effect. The emphasis is on the need for vigilance in managing the dosage and monitoring the patient's condition closely when administering these types of medications.