Rocephin IM and needle gauge

I wanted to confirm some thoughts about giving rocephin. My friend is getting daily injections, and she has been using a 25 gauge needle to both reconstitute and inject the med. I think this size is way too small! I think she should use at least a 23 gauge 1 inch or larger bore and split the 4.2cc in two injections. She is using the dorsogluteal site which is good. Any thoughts or confirmations would be greatly appreciated.