Why can it be dangerous to administer drugs to patients in renal failure?

Poor excretion: A great number of drugs are excreted through kidneys into urine. When kidneys are functioning at suboptimal level, these drugs or its metabolites (breakdowns) become accumulated at high level in blood and increase side effects thereof.

Medications in RF: Many medications and/or the byproducts that come from taking a medication have to get out of your body by way of your kidneys. Also, some medications can, at high levels in your blood, damage your kidneys. Virtually every drug given to a renal failure patient needs to first be looked at from the standpoint of the need to alter dosing before being given. This is really important.