My Friend, Diagnosed With Metastatic Prostate Cancer Has Just Returned

My friend, diagnosed with metastatic prostate cancer has just returned from a radiation treatment with a new prescription for dexamethasone and a lot of pills with TEC on them which I see are prescribed for opiate withdrawal. Is this TEC pill part of the radiation treatment or has it been prescribed for actual withdrawal. I know that he had opiates in his system during his last blood tests and probably pretty high levels. I also know that this was a one time occurrence. My real question is are these pills necessary if he is not going through withdrawal and could they be doing him more harm than good? Saying this costs money first would have been nice. thank you have a nice day.