The problem is not with doctors who did not monitor the problem, it is with patients who do not tell their doctors about side effects or adverse reactions from a drug.
Perhaps, but when my doctor had me taking a cholesterol-lowering drug, I reported side effects of muscle pain, etc. and he said "that's not from the drug" and wanted me to continue. I stopped taking them on my own, against his wishes, with absolutely no change in my cholesterol levels! A year or two later, patients were dying from these statin drugs. Now they take the side effect reports more seriously.