Elderly patients have several unique issues related
to antibiotic therapy. In addition to age-associated physiological changes and drug-drug
interactions, adverse drug reactions are also a noteworthy concern specific to this population. By
using evidence-based medicine, pharmacists can help identify, prevent and resolve adverse drug
related problems in the elderly. Common adverse effects seen in the elderly on antibiotics include:
dizziness, renal toxicity, hyperkalemia, blood dyscrasias, seizures, esophageal ulceration and acute liver injury.1
Aminoglycosides-renal and auditory toxicity
Aminoglycosides are associated with potentially irreversible
nephrotoxicity and ototoxicity. Risk factors for these adverse effects include: older age, higher
dosages, longer duration of therapy, renal insufficiency and concomitant medications that also have
a higher risk of renal or auditory toxicity (eg amphotericin B, cyclosporine, vancomycin, contrast
agents and loop diuretics).1,2 Dizziness, including vertigo, has been associated with
antibiotics that affect the inner ear, such as aminoglycosides. Considering that this toxicity of
aminoglycosides often manifests with ineffective renal elimination, this can be problematic in the
elderly, who have a notably higher incidence of renal impairment. Most importantly, dizziness
is of concern since this is also a population
where balance and stability are already problematic and fall risk should be minimized.
Trimethoprim and sulfamethoxazole-induced hyperkalemia and
The elderly population already has a high prevalence of renal
impairment and cardiac disease. Trimethoprim can
increase serum potassium levels by decreasing renal excretion. Hyperkalemia may also be of higher
risk in those on angiotensin converting enzyme (ACE) inhibitors or potassium-sparing diuretics,
agents that are prevalent with those of advanced age. The commonly prescribed combination
antibiotic, trimethoprim and sulfamethoxazole, may also be of concern for the elderly in regards to
folic acid deficiency. Folic acid deficiency is already a common vitamin deficiency in the elderly,
and this can ultimately lead to megaloblastic anemia.2
Fluoroquinolone-related seizures and QT
This class of antibiotics has been associated with central
nervous system (CNS) stimulatory effects and cardiac arrhythmias. Although seizures are rare, these
agents should be used in caution for elderly patients or those with preexisting CNS disorders or
epilepsy.3 Advanced age, female gender and those with existing QT prolongation or known
risk factors (i.e., concomitant medications that increase the QT interval) are at high risk for QT
prolongation with fluoroquinolone therapy.4 Some medications associated with QT
prolongation include: antiarrhythmic drugs, certain nonsedating antihistamines, macrolides, certain
psychotropic medications and certain gastric motility agents. Use of fluoroquinolones should be
avoided in elderly patients that are at high risk for QT prolongation.
Doxycycline-related esophageal ulcerations &
Since elderly patients are more likely to have comorbidities
related to esophageal damage (i.e., gastroesophogeal reflux disease) and use medications that can
cause esophageal damage (i.e., aspirin, bisphosphonates, nonsteroidal anti-inflammatory drugs),
doxycycline poses an increased threat for esophageal ulcerations and strictures. Administering
doxycycline with 8 oz. of water and instructing elderly patients to sit up for 30 minutes can help
reduce the risk of esophageal irritation and ulceration.1,2
Acute liver injury secondary to prolonged
Amoxicillin/clavulanate therapy is an appropriate
antimicrobial choice for outpatient management of community-acquired pneumonia in the
elderly.5 Some data suggest that advanced age and longer duration of therapy are
predisposing risk factors. With prolonged therapy, hepatic function should be monitored more
closely in the elderly population.2,6 In addition to risk for adverse effects, elderly
patients have age-related physiological changes, polypharmacy and comorbidities that increase their
risk of drug-related problems when administering antibiotics. Clostridium difficile infection (CDI)
is a growing area of concern in this patient population, which has higher morbidity and mortality
with CDI.6 As healthcare providers, we play a key role in recognizing the potential for
adverse related drug reactions that are often seen with antibiotic therapy in the elderly
population to mitigate these risks in our patients.
- Zagaria ME. Antibiotic Therapy: Adverse
Effects and Dosing Consideration.US Pharm.
- Millan J, Gleckman R. Selecting the
right antibiotics for elderly patients. J Crit Illness.
- Leroy, B, Uhart M, Maire P et al.
Evaluation of fluoroquinolones reduced dosage requirements in elderly patients by using
pharmacokinetic modeling and Monte Carlo simulations. K Antimicrob Chemother. 2012;67:2207-2212
- Drew BJ, Ackerman MJ, Funk M, et al.
Prevention of torsade de pointes in hospital settings: a scientific statement from the
American Heart Association and the American College of Cardiology Foundation. Circulation. 2010;121(8):1047.
- Garcia Rodriguez LA, Stricker BH,
Zimmerman HJ. Risk of acute liver injury associated with the combination of amoxicillin and
clavulanic acid. Arch Intern Med.
- Kee VR Clostridium Difficile Infection
in Older Adults: A Review and Update on Its Management. Am J Geriatr Pharmacother.