What antibiotics are avoided or used with caution in geriatric patients due to potential adverse effects?

Antibiotics to Avoid or Use with Caution in Geriatric Patients

Several classes of antibiotics should be avoided or used with significant caution in geriatric patients due to increased risk of adverse effects and altered pharmacokinetics.

Antibiotics to Avoid

• Aminoglycosides (gentamicin, tobramycin) should be avoided when possible in geriatric patients due to increased risk of nephrotoxicity and ototoxicity, especially in those with pre-existing renal impairment, advanced age, and dehydration 1, 2
• Fluoroquinolones should be avoided in geriatric patients with impaired renal function, known QT interval prolongation, or CNS disorders due to increased risk of tendinopathy, CNS effects, and QT prolongation 3
• Trimethoprim-sulfamethoxazole (TMP-SMX) should be used with caution in patients with reduced kidney function who are taking ACE inhibitors or ARBs due to increased risk of hyperkalemia 4

Antibiotics Requiring Dose Adjustment

• Fluoroquinolones require significant dose adjustment in renal impairment:

  • Ciprofloxacin: Reduce dose by 50% when GFR < 15 ml/min/1.73 m² 4
  • Levofloxacin: For CrCl 20-49 ml/min: 750 mg initially, then 750 mg every 48 hours; For CrCl 10-19 ml/min: 500 mg initially, then 500 mg every 48 hours 5

• Macrolides: Reduce dose by 50% when GFR < 30 ml/min/1.73 m² 4

• Penicillins: Risk of crystalluria when GFR < 15 ml/min/1.73 m² with high doses; neurotoxicity with benzylpenicillin when GFR < 15 ml/min/1.73 m² with high doses (maximum 6 g/day) 4

Drug-Drug Interactions to Avoid

• TMP-SMX with phenytoin or warfarin increases risk of phenytoin toxicity and bleeding 4
• Macrolides (excluding azithromycin) or ciprofloxacin with warfarin increases bleeding risk 4
• Ciprofloxacin with theophylline increases risk of theophylline toxicity 4
• Aminoglycosides with other nephrotoxic drugs (cisplatin, cephaloridine, kanamycin, amikacin, neomycin, polymyxin B, colistin, paromomycin, streptomycin, tobramycin, vancomycin, viomycin) should be avoided 1
• Aminoglycosides with potent diuretics (ethacrynic acid, furosemide) should be avoided due to increased ototoxicity risk 1

Monitoring Recommendations

• For aminoglycosides, monitor:

  • Renal function (BUN, serum creatinine, creatinine clearance)
  • Serum drug levels (avoid peak concentrations above 12 mcg/mL and trough levels above 2 mcg/mL)
  • Auditory and vestibular function 1, 6

• For all antibiotics in geriatric patients:

  • Calculate creatinine clearance rather than relying solely on serum creatinine 5, 6
  • Monitor for CNS effects including confusion, which may be mistakenly attributed to age 3
  • Consider drug-drug interactions due to common polypharmacy in elderly 7

Common Pitfalls to Avoid

• Failing to calculate creatinine clearance and relying solely on serum creatinine, which can lead to inappropriate dosing 5, 6
• Not recognizing atypical presentation of infections in elderly patients, which can lead to delayed diagnosis and treatment 4
• Overlooking drug-drug interactions in elderly patients who are often on multiple medications 7
• Attributing adverse drug reactions (confusion, weakness, loss of appetite, tremor, depression) to age rather than medication effects 3

Safer Alternatives

• When possible, select antibiotics with less renal elimination and lower nephrotoxicity potential 5
• For UTIs in elderly patients, fosfomycin, nitrofurantoin, and pivmecillinam may be preferred options when appropriate for the infection 4
• Consider the local resistance patterns when selecting empiric therapy 7

Remember that physiological changes associated with aging, including decreased renal function, altered body composition, and increased susceptibility to adverse effects, necessitate careful antibiotic selection and dosing in geriatric patients 7, 6.