I just wanted to second what Ides said. I thought that medicare covered the specialty drugs, and enbrel (along with remicade and humira and others) are considered specialty drugs. Like your mom, I cannot handle many of the narcotic pain killers. They make me very sick. I've been taking tramadol, however, for the past 9 months with no problems at all. Well, aside from the fact that my insurance doesn't want to pay for it as a maintenance drug (but that's just a quirk with my insurance company). It's a fairly inexpensive drug.
I truly hope your mother can find something that will provide her some relief.
Current dx: Rheumatoid Arthritis
Suspected dx: UCTD/Early Lupus
Current Meds: Enbrel, Plaquenil, Aciphex, Ultracet, Zyrtec, Allavert-D, Zantac, Tylenol PM
Past Meds: Relafen, Vioxx, Mobic, Voltaren, Sulfasalazine, Entocort, Prednisone, Humira, Reglan