Route of drug abbreviation question

Hello, so I'm a nursing student and was looking at my patients chart for tomorrow and I noticed the route of multiple drugs says GTB. I have no clue what this stands for. Some the the meds whose route said GTB were Coreg, Lopid, and Prevacid (to name a few). Does it have to do with g tube? Thanks in advance.
I believe that it is G-tube bolus.However, it is always best, if you have a question about a hospital abbreviation, that you ask the pts nurse, or the charge nurse or even better, look it up at the facility. Facilities often have their own list of hospital acceptable abbreviations.

Does the patient have a GT?