A higher therapeutic index indicates that:

A higher therapeutic index indicates that a drug is safer. The therapeutic index is a ratio that compares the dose of a drug that produces a therapeutic effect to the dose that produces toxicity. A wider margin between the effective dose and the toxic dose suggests that there is a greater range of doses at which the drug can be used safely without causing harmful effects. Consequently, this higher therapeutic index means that the likelihood of adverse effects occurring at therapeutic doses decreases, indicating a safer profile for the drug in question.

In contrast, a lower therapeutic index would demonstrate a higher risk of toxicity and a narrower range for safe usage, which emphasizes the importance of understanding the therapeutic index when considering drug safety and efficacy.