Actually, the meds for ADHD should make a difference. But you have to hit the right dosage. Docs start out low and go slow with the meds waiting for parental feedback, so definitely stay in touch with your doctor. If you have not seen a change, it may be that you are not yet using the right dose or the right med.
And, of course, there is a lot more that can be done for a child with ODD. Here are two very good links on working with a child with ODD.
I would certainly give the stim meds a chance to work and the techniques mentioned in the links above, before I started looking at any other types of meds.
Hope this helps.