Go with vaping, get a real deep kush and keep the vape temperatures really low. After a few weeks of doing this for pain relief she won't get a "head high" ever again, unless she stops. I find her position irresponsible though, and I think anyone, even an arthritis sufferer, who considers opiates, is in a serious at-risk category. If they are shunning other treatments in favor of opiates, I would go as far as to suggest drug abuse counseling as a preventative measure. I'm completely serious about this.