Which of the following statements is true about narrow therapeutic index (NTI) drugs?

Narrow therapeutic index (NTI) drugs are characterized by having a small margin between their effective dose and their toxic dose. This means that slight variations in drug concentration can lead to therapeutic failure or toxicity. Therefore, careful titration and monitoring are essential when using these medications to ensure that patients receive the correct dose without exceeding the threshold that could result in adverse effects.

For instance, drugs like warfarin, lithium, and levothyroxine fall under the category of NTI drugs. They often require regular blood tests to monitor therapeutic levels, and adjustments may be necessary based on those results. This diligent monitoring helps to maintain the desired level of medication in the patient's system, thus minimizing risks associated with both underdosing and overdosing.

The other options do not accurately reflect the nature of NTI drugs. For example, stating that these drugs are safe and do not require monitoring overlooks the fundamental need for cautious management and could put patients at risk. Similarly, the idea that they can be titrated without concern for dosage fails to recognize the necessary precision involved in their use, while declaring that they have a wide range of effective dosages contradicts the core concept of a narrow therapeutic index, which implies a limited range.