Economics has lowkey very little related to mpharm at uni unless you plan to start a pharm business later... And even then you will get more out of experience then econ A-level... Also it has a lot of maths concepts and essays...
Pyschology is a lot more related, it teaches you research skills (useful for if you end up doing pharmacology at a pharmaceutical company) and also teaches you about mental health and mental health illnesses (which is useful as lots of drugs are targetted at treating mh conditions so you have some prior knowledge), also it has essays...
Neither are 'easy' subjects, you have to work hard in A-levels to get a good grade, however unless you already really like econ, most people struggle to enjoy it as it is very politics adjacent... Pyschology tends to more interesting as its more relatable so is more interesting