Odansetron and Dexamethasone Alone vs. Odansetron, Dexamethason and Apreptant to Prevent Nausea

Dexamethasone 10 mg (dose blinded) in 50 ml D5W IVPB over 15 minutes daily + ondansetron 8mg PO q 8 hours - repeated qd of the preparative regimen and for 1 day after completion. A placebo capsule will be given daily on each day of the preparative regimen plus 3 days after. Antiemetic therapy will start a minimum of 30 minutes prior to and continued for 24 hours after completion of the preparative regimen.

Dexamethasone 7.5 mg (dose blinded) in 50 ml D5W IVPB over 15 min daily + ondansetron 8mg PO q 8 hours - repeated QD of the preparative regimen and for 1 day after completion. Aprepitant 125mg PO \[blinded\] will be given a minimum of 30 minutes prior to the preparative regimen on day 1. MK-Aprepitant 80mg PO \[blinded\] will be given will be given approximately 24 hours later starting on day 2 then each day of the preparative regimen plus 3 days after. Antiemetic therapy will start a minimum of 30 minutes prior to and continued for 24 hours after completion of the preparative regimen.