Which non-opioid drug has onset 30 seconds to 2 minutes and is a muscle relaxant that can cause phlebitis when given IV?

• A. Diazepam (Valium)
• B. Lorazepam
• C. Midazolam
• D. Alprazolam

Answer: (A)

Benzodiazepines given IV act quickly to provide both sedation and muscle relaxation, and the timing helps distinguish them. Diazepam stands out because its IV onset is very rapid, around 30 seconds to a couple of minutes, and it has noticeable central muscle-relaxant effects without being an opioid. A known drawback of IV diazepam is venous irritation leading to phlebitis, largely due to the solvent it’s formulated with, especially if given rapidly or undiluted.

Lorazepam tends to have a slower IV onset and isn’t used primarily for muscle relaxation. Midazolam is also very fast-acting and used mainly for sedation, not as a muscle relaxant, and alprazolam is not given IV and is used orally. So the combination of very rapid IV onset, muscle-relaxant effect, and a recognized risk of phlebitis with IV administration makes diazepam the best answer.