The process and procedures for getting a drug out for use by the public it's long and rigorous. A lot of test are conducted. During preclinical trials, the drug is tested in the lab on animals to see if it is dangerous or safe. Then comes the clinical trials and if it should pass the safety and efficiency testing, then it gets to the public.

As long as the procedure was followed, you can trust it. But in homeopathy, you can not be sure.