What is primarily responsible for venoirritation and thrombophlebitis during the injection of Diazepam?

Propylene glycol is primarily responsible for venoirritation and thrombophlebitis during the injection of Diazepam. Propylene glycol is often used as a solvent for many injectable medications, including Diazepam, due to its ability to dissolve substances that have low solubility in water. However, it can be irritating to the endothelial cells of veins, leading to local inflammation and venous irritation, which manifests as thrombophlebitis.

This effect is exacerbated in inflamed or damaged blood vessels but can also occur in healthy veins if the dosage or rate of injection is not adequately managed. This is particularly significant because Diazepam is often administered intravenously, where the potential for irritation is heightened.

While the other substances mentioned—benzyl alcohol, ethyl alcohol, and polyethylene glycol—may have their own side effects or implications, propylene glycol is specifically noted for its role in causing venoirritation and is a common factor in the formulation of Diazepam injections. Thus, it is essential for practitioners to be aware of this side effect when administering this medication intravenously.