Most likely he would have died anyway, only he did it at home, and not in a
sterile lonely little cage in
No doubt his injury was worse than expected, or something happened, such as a blood clot, or haemorrage.
I'm sorry, but I have no experience of those medications, with the exception of Metaclorpromide (for nausea) And I do doubt that he would have had a fatal reaction to that.
But other people do post here who know far more than I do, so check back in case.