What factors can lead to altered drug clearance in renal impairment?

Altered drug clearance in renal impairment primarily results from changes in the glomerular filtration rate (GFR) and the processes of tubular secretion and reabsorption. In renal impairment, the GFR is typically reduced, which leads to decreased filtration of substances from the blood into the urine. This reduction significantly impacts the elimination of medications that are primarily excreted unchanged by the kidneys.

Additionally, tubular secretion and reabsorption processes are critical for the clearance of certain drugs. In cases of renal impairment, the transport mechanisms responsible for secreting substances into the renal tubules may be compromised. This can lead to decreased drug elimination and potentially increased drug levels in the bloodstream, resulting in toxicity or enhanced side effects.

Understanding these renal processes is crucial in pharmacokinetics since it directly informs dosing adjustments for medications that are cleared by the kidneys. Monitoring renal function and understanding these changes help clinicians optimize drug therapy in patients with renal impairment.