Abstract Adverse drug effects as a consequence of
inappropriate dosage are a common cause of hospitalization
among the elderly. Older individuals are at a particular
risk of overdosing because their kidney function decreases
with advancing age and the elderly are often prescribed
several pharmaceutical drugs. In addition, serum creatinine
levels decrease owing to a reduction in muscle mass with
age. Therefore, drug dosing based on the serum creatinine
level only, instead of using assessment of the renal function,
may result in overdosing of frail elderly patients.
Renal function, i.e., the glomerular filtration rate can, with
simple formulas, be estimated from analysis of creatinine
and/or plasma cystatin C (eGFR). Such estimations performed
with modern and validated formulas, as a rule
present renal function normalized to the body surface area
(mL/min/1.73 m2
). A good estimation of how much the
normal dosing interval should be prolonged, or the dose
reduced, to obtain a desired plasma concentration of drugs
that are mainly eliminated by glomerular filtration can be
obtained by calculating the ratio between the patient’s
eGFR and the normal renal function (about 90–125 mL/
min/1.73 m2
). Increased knowledge and use of eGFR by
prescribing physicians will reduce the risk of overdosing
drugs in the elderly