D

Doxycycline is eliminated largely via the bile and gastrointestinal tract; pharmacokinetic studies show that its serum half-life and clearance are essentially unchanged in patients with severe renal impairment, so no dosage adjustment is needed [Mahon 1970, PMID 5494820]. In contrast, vancomycin and aminoglycosides such as gentamicin are primarily renally excreted, and standard dosing guidelines call for dose or interval reduction in renal dysfunction; the same renal-based adjustments are recommended for amphotericin B formulations because of their nephrotoxicity [Van Scoy 1987, PMID 3682959].