Anyone use or have used alternating Ondansetron and Cerenia?

My vet wants me to alternate, one day cerenia, one day ondansetron...has anyone done this, does it make sense to control nausea/vomiting? 

Isn't just using Cerenia doing the trick?  Is there some reason why he wants to do this odd combo thing?  What's it needed for anyway (why the nausea?)....is this short term or long term?

Hi, Mrsgreenjeans.  Good questions.  Obi has a few Issues that are not clear.  GI issues.  Recently I had him ultrasounded - the vet found three small spots on his spleen, of indeterminate nature.  I am not having him biopsied or having the spleen removed.  I know a lot of IBD kitties progress to SCL, but mostly Obi has not demonstrated the symptoms that run concurrent with small cell lymphoma, or a mast cell tumor.  A couple of nights he tossed a hairball; then the next day, he vomited in the middle of the night; next day he regurgitated his dinner; and this morning, another hairball.  He has been on cerenia but that does not prevent hairballs, nor should it.  He has been on Ondansetron, and still vomited the other evening.  His weight is good and his chem panel of a month ago was perfect.  So, to answer your questions, the vet is trying to prevent vomiting...I am not a big fan of Cerenia because Obi loses his appetite on it..Unusual, I know, but not unheard of.  I think its a short term plan.  He is also on 2 EYL capsules daily for the hairballs...sigh.  and pred.  5 mg.  and a probiotic.  and spyllium.  And gabapentin.     

Poor Obi .  Well, hopefully this mixture will work for him

Two summers ago, when Obi had  a bout with pancreatitis, I had three "specialists" tell me Obi "probably" had small cell lymphoma.  That was over two years ago.  I do not believe he had it then, as he has not lost weight, he does not have diahrrea, nor does he generally vomit - except for hairballs.  So I sometimes take what vets say with a grain of sceptism, although I really like his current vet, and she tries very hard to keep him comfortable.  Yesterday I bought him some raised food bowls, and he looks more comfortable eating now.  Last night he ate really well.