What does a high therapeutic index indicate?

A high therapeutic index indicates a wider safety margin for a drug, signifying that there is a significant difference between the effective dose and the toxic dose. The therapeutic index is a ratio comparing the dose of a drug that produces a therapeutic effect to the dose that produces a toxic effect. A higher ratio means that there is a larger range in which the drug can be safely administered without the risk of causing toxicity.

This wider safety margin is crucial for ensuring that patients receive effective treatment with reduced risk of adverse effects. Medications with a high therapeutic index are generally considered safer, as there is less likelihood that the drug will reach levels that could cause harm to the patient.

In contrast, other options highlight differing implications. A greater risk of toxicity is associated with a lower therapeutic index, while lower effectiveness relates to the drug's inability to achieve its intended therapeutic effect, which is not indicated by the index itself. Lastly, faster metabolism does not directly relate to the therapeutic index, as it pertains to how quickly the drug is processed in the body rather than its safety margin.