From the FDA Drug Label
The pharmacokinetics of levofloxacin in patients with serious community-acquired bacterial infections are comparable to those observed in healthy subjects The potential for pharmacokinetic drug interactions between levofloxacin and antacids, warfarin, theophylline, cyclosporine, digoxin, probenecid, and cimetidine has been evaluated Levofloxacin has in vitro activity against Gram-negative and Gram-positive bacteria fections as described in Indications and Usage (1): Streptococcus pneumoniae (including multi-drug resistant isolates [MDRSP] )
- Levofloxacin is a suitable option for an 88-year-old patient with pneumonia, taking warfarin, and having allergies to penicillin and sulfa, as it has in vitro activity against Streptococcus pneumoniae, including multi-drug resistant isolates, and its pharmacokinetics are not expected to be affected by warfarin 1.
- Azithromycin may also be considered, as it is indicated for the treatment of community-acquired pneumonia due to Streptococcus pneumoniae in patients appropriate for oral therapy, but caution should be exercised due to the patient's age and potential risk of QT prolongation 2 2.
From the Research
For an 88-year-old patient with pneumonia who is on warfarin for atrial fibrillation and has allergies to penicillin and sulfa drugs, the most suitable antibiotic option is a respiratory fluoroquinolone such as levofloxacin 750 mg once daily for 5-7 days, as it has a broad spectrum of activity against common respiratory pathogens, including Streptococcus pneumoniae, Haemophilus influenzae, and atypical organisms, and is well-tolerated in elderly patients 3. When selecting an antibiotic, it is essential to consider the patient's allergies and the potential interactions with warfarin, as fluoroquinolones can increase the risk of bleeding 4. Some key points to consider when prescribing antibiotics for this patient include:
- Monitoring the patient's INR closely to minimize the risk of bleeding complications
- Ensuring adequate hydration to prevent dehydration and potential kidney damage
- Considering symptomatic treatment for cough and wheezing with bronchodilators if appropriate
- Avoiding beta-lactams and sulfonamides due to the patient's allergies Alternative options, such as macrolides like azithromycin, may be considered if the patient has no QT prolongation risk factors, but fluoroquinolones are generally preferred due to their broader spectrum of activity and efficacy in treating community-acquired pneumonia 5, 6, 7.