One form of ondansetron is a rapidly dissolving tablet (Zofran ODT). If you use Zofran ODT, do not remove the tablet from its foil pocket until just before you take it. You should not take Zofran if you take a drug called apomorphine, which is an injectable drug used to treat Parkinson’s disease. The combination of apomorphine and ondansetron can cause dangerously low blood pressure.