See Medicinal Chemistry and Biotechnology both can help you to fulfill your dreams but you have to choose the most efficient way. In general the pharmaceutical and drug developing companies prefers the Biotechnologists due to their varied conceptual skills in the field of technology as well as development in Biology. But in Medicinal chemistry to be a expert you have to go for Masters or PhD in order to get a position but with Biotechnology you may have a good chance to get a job after your Bachelors.

I hope this might give you some points. All the very best for your future endeavors!