Which compound is primarily used as a target drug in benzodiazepine screening?

The correct choice is oxazepam, which is primarily used as a target drug in benzodiazepine screening. Oxazepam is a benzodiazepine that is often detectable in urine and blood tests, making it a common marker for identifying the presence of this class of drugs in a patient's system. Its specific metabolic pathway and the frequency of prescription contribute to its prominence in toxicology screenings.

When laboratories perform benzodiazepine screening, they typically look for substances that represent the broader category of benzodiazepines. Oxazepam is one such representative, as it is stable and predictable in how it is metabolized, allowing for reliable detection.

Other benzodiazepines like diazepam and nordiazepam are also important; however, oxazepam is particularly noted for its relevance in screening protocols due to its specific characteristics and the patterns of its use in clinical settings. Flumazenil, while a benzodiazepine antagonist used in reversing benzodiazepine overdose, does not serve as a target drug for screening purposes. Instead, it plays a different role in managing benzodiazepine effects rather than being a marker for their use.