An LPN is not permitted to administer any drug type through an IV line.
The LPN can flush an IV line in preparation for the RN to administer the medication, but the LPN cannot do it.
LPNs can, however, administer oral medications, topicals, and other treatments to patients.
RNs often ask LPNs to give all medications, including IVs, if they are busy.
However, it is important to understand the rules of your facility and the consequences of your actions if you choose to break those rules.