My GP has said he will no longer allow me to take Arimidex and has prescribed a generic Anastrozole.  When I was first prescribed an aromatase inhibitor I was given Letrozole.  I tried 2 of the generic Letrozole and suffered a lot of stiffness, etc which was so bad I had difficulty getting out of bed and was hunched over.  I felt so bad that I was about to give up on AIs until my then GP kindly prescribed Femara. 

I stayed on the Femara AI for over a year until I was getting palpitations etc. More recently I changed surgeries and I asked to be prescribed Arimidex, as I read it allowed some estrogen to remain in the system and was perhaps the 'kinder' of the 3 AIs.  I was prescribed this for 3 months and then diagnosed with heart problems and so stopped taking it.

My Oncologist suggested that I start taking Anastrozole again. My GP will now only prescribe the generic form of this drug, apparently due to budget constraints.  I do not want to go down the route, again, of extreme stiffness if I am forced by my GP to try a variety of generic Anastrozole as I am already suffering with a lot of stiffness in my shoulders, hips, knee, back etc and I have osteopenia which a DEXA scan has shown bone lose is worsening in the spine. Being forced to try a variety of generic versions of this, or any, drug is detrimental to the health care of me as the patient.

Do I have any rights to ask to return to Arimidex?  Is there a procedure that I could follow to make sure that I DO get the version of the drug that I want?