The nurse is administering medications to the patient who is in renal failure resulting from end-stage renal disease.
The nurse is aware that patients with kidney failure would most likely have problems with which pharmacokinetic phase?

Choice A rationale

Metabolism is primarily carried out by the liver, involving enzymatic biotransformation of drugs into more hydrophilic metabolites for excretion. While liver function can be impacted by systemic illness, renal failure's direct effect on drug metabolism is less significant than its impact on elimination. The liver's cytochrome P450 system typically remains functional.

Choice B rationale

Excretion is the primary elimination pathway for many drugs and their metabolites, mainly via the kidneys. In end-stage renal disease, glomerular filtration rate and tubular secretion are severely impaired, leading to accumulation of drugs and their toxic metabolites, necessitating dose adjustments or alternative elimination methods. Normal creatinine clearance is 80-120 mL/min.

Choice C rationale

Absorption refers to the movement of a drug from its administration site into the bloodstream. While renal failure can indirectly affect absorption through gastrointestinal changes (e.g., uremia-induced nausea), it is not the primary pharmacokinetic phase directly compromised by impaired kidney function. Bioavailability might be altered but not the fundamental absorption process.

Choice D rationale

Distribution involves the reversible movement of a drug from the systemic circulation into the interstitial and intracellular fluids. Renal failure can impact drug distribution due to fluid imbalances, altered protein binding (e.g., hypoalbuminemia), and changes in tissue perfusion, but it is not the most significant or direct pharmacokinetic impairment compared to excretion.