offlabel

Pain management is a frequent 'default' fall back alternative for both medical and nursing anesthesia trainees that are questioning their choice of sub-specialty. It is horrible advice. Pain is a very specific sub-specialty that just happens to have crossover skills in anesthesia but is in another galaxy in terms of clinical expertise, knowledge base and medical emphasis. It is far more suited to someone interested in internal/general medicine than anesthesia. Anyone can learn to put a needle in a certain spot. Monkey skill. To suggest it as a 'bail out' from anesthesia is professional suicide. 

If a CRNA with prescriptive authority starts writing scripts for antibiotics, misc. med refills, or some other non-practice related reasons (like their neighbor needs something) he or she will definitely get the attention of the local board of pharmacy.
Many CRNA's that have prescriptive authority do so only because their group/hospital thinks it will take some kind of liability away from them and compel the CRNA's to have it. Same with a DEA number. Not necessary per se for the general practice CRNA, but many have it. And it doesn't change a single thing. 
PP pain is another thing but is definitely the minority of CRNA business.