Is semaglutide itself patented, or is it the pen/delivery mechanism? The online sellers provide vials of semaglutide that need to be reconstituted and then draw

Is semaglutide itself patented, or is it the pen/delivery mechanism? The online sellers provide vials of semaglutide that need to be reconstituted and then drawn up / injected like insulin or other vial-based peptides. I assumed this is legal and possible because the patent is actually on the pen and not the peptide itself. But I haven't been able to confirm that one way or another. Even if that is the case, the ease of use is no doubt to me a huge part of the reason it has been so successful. I don't think it would have seen such widespread use if it were only available in vials.