personally have not heard of anyone who is pursuing a PhD and aspries to do an MBA. I would suggest put your focus on either one and try to finish at least one of them depending on what you want to do.
Transition can be done, if that is what you want but it is very important you figure out what you intend to do in future.
You can also try to get in touch with consellors and instituitions that can guide you and also help you in transition if it appears to be a good idea. manya education site will help you answer your questions in detail.
Is anybody out there pursuing PhD and aspire to do an MBA. What are your focus and how you feel about the transition?