<p>I’m not sure how difficult it is to change from pharm-sci to biochem, but the good thing about pharm-sci is that if you study it undergrad and decide it’s not for you, because you took many of the same courses as biochem majors you can most likely go on to biochemistry graduate school afterwards. 
My dad was a biology and chemistry double major at UCI and really liked the programs, and I’m going into UCI this fall as a pharm-sci major, so I may be biased, but if you’re interested at all in pharmaceutical development (pharmacology) or becoming a pharmacist, it might be a good major to stick to. However, UCI has really good biology and amazing chemistry, so I completely understand why you would want to go into their biochem major. Best of luck! :)</p>