Renal and Hepatic Prescribing Flashcards

Which anticoagulant is generally preferred for a patient with severe renal impairment (CrCl <15 mL/min) requiring long-term anticoagulation?

Answer: Warfarin

Direct oral anticoagulants (DOACs) are substantially renally excreted and accumulate dangerously in severe renal impairment; warfarin, being hepatically metabolized, is preferred.

Spironolactone is generally contraindicated in patients with severe renal impairment (eGFR <30 mL/min) primarily due to the risk of:

Answer: Life-threatening hyperkalemia

Spironolactone blocks aldosterone-mediated potassium excretion; in renal impairment, already-reduced potassium clearance combined with this effect causes dangerous hyperkalemia.

In hepatic impairment, which plasma protein is most significantly reduced, leading to increased free drug fractions of highly protein-bound medications?

Answer: Albumin

Albumin, synthesized by the liver, is reduced in hepatic impairment, increasing the free fraction of acidic drugs like phenytoin, warfarin, and furosemide.

A patient with severe hepatic impairment requires analgesia for moderate pain. Which approach is most appropriate?

Answer: Low-dose paracetamol (500mg TDS) with careful monitoring

Low-dose paracetamol with monitoring is safer than NSAIDs (GI bleeding and renal risk in cirrhosis) or opioids (risk of precipitating hepatic encephalopathy).

Which antibiotic is almost entirely renally excreted and requires the most significant dose reduction when CrCl falls below 30 mL/min to prevent nephrotoxicity and ototoxicity?

Answer: Gentamicin

Gentamicin is almost entirely renally excreted unchanged; dose reduction and interval extension are essential in renal impairment to prevent nephrotoxicity and ototoxicity.

Regarding drug dosing in renal impairment, which statement about loading doses versus maintenance doses is CORRECT?

Answer: Maintenance doses require reduction but loading doses are generally unchanged

Loading doses are determined by volume of distribution (generally unchanged in renal impairment) and achieve target concentrations rapidly; maintenance doses must be reduced to prevent accumulation.

A patient with renal impairment is taking lithium for bipolar disorder. Reduced renal clearance of lithium most critically predisposes to:

Answer: Neurotoxicity including coarse tremor, confusion, and seizures

Lithium toxicity due to accumulation from reduced renal clearance manifests primarily as neurotoxicity — coarse tremor, confusion, ataxia, and at high levels, seizures and coma.