What is meant by off-label use of an anti-TB drug?

Off-label use of an anti-TB drug refers to its administration for purposes that are not included in the labeling approved by the manufacturer. This can involve prescribing the drug for a different condition, at a different dose, or through different routes of administration than what is specified. Off-label use is common in medicine when healthcare professionals believe that a medication may be beneficial for a patient based on emerging evidence or clinical judgment, even if that use has not gone through the formal approval process.

In contrast, the definitions provided in the other choices emphasize conforming to established protocols or the manufacturer’s labeling, which do not pertain to off-label use. For example, using a drug strictly according to the manufacturer's indications aligns with established treatment protocols, while refusal to use the drug and using it only in clinical trials would not reflect off-label practices. The concept of off-label use is significant in the realm of tuberculosis treatment, especially in instances where a patient may be resistant to standard therapies or present with atypical cases.