arthritis meds

I see your add for arthrogen, what is the difference between that and other perscription meds for arthritis such as cosequin? I have a cat that should be on that, but I CANNOT get him to take it. Any tips? I have tried wet food, dry food, in treats, peanut butter and others. He is very picky. he just smells it an walks off. I reduced his weight and that has helped 90% but I know he still has problems and he is only getting older.