What type of needle should a pharmacy technician use to inject a diluent into a vial for a powder medication?

Using a vented needle to inject a diluent into a vial for a powder medication is the correct approach because it allows air to enter the vial as the liquid is drawn out. When a vial is sealed, creating a vacuum, using a standard needle can create negative pressure, making it difficult to withdraw the solution. A vented needle has a small hole that permits air to flow into the vial, balancing the pressure and ensuring that the diluent can be easily injected without creating a vacuum that would impede the fluid transfer.

In contrast, a regular needle might not provide the necessary air exchange, leading to potential complications during reconstitution. An insulin needle is typically shorter and may not be suitable for drawing larger volumes of liquid from a vial. An intravenous needle is specifically designed for different tasks associated with IV administration and is generally not used for accessing vials in this context. Therefore, the vented needle is the best choice for this procedure.