Infection asked
Is it safe for an older woman to start taking Levaquin 750 mg once a day for 10 days a couple of days after finishing a Z-Pak?
At a glance
- Levaquin (levofloxacin) and Zithromax (azithromycin) generally aren't used at the same time.
- Taking both increases the risk of certain side effects, such as QT prolongation and torsade de pointes.
- They can be used one after the other however, depending on the situation.
Answer
In general, Levaquin (levofloxacin) and the Z-Pak (azithromycin) aren't used together.
Not only is it uncommon to combine antibiotics for most infections (there are exceptions of course), how both antibiotics (Levaquin & Z-Pak) exert their antibacterial effects often precludes their concomitant use.
- Levaquin (levofloxacin) is a bactericidal antibiotic, meaning it actively kills bacteria once high enough concentrations are reached.
- The Z-Pak (azithromycin) is a bacteriostatic antibiotic, meaning it simply inhibits growth and replication of bacteria.
In many cases, it generally isn't recommended to combine bactericidal and bacteriostatic antibiotics, but there are exceptions. In addition, it's important to note that both Levaquin and the Z-Pak have been reported to exhibit both properties, depending on the type of bacteria.
What's more concerning regarding use of Levaquin and the Z-Pak together is the potential for an increased risk of heart arrhythmias.
Levaquin With Azithromycin
It is recommended to avoid concurrent use of Levaquin (levofloxacin) and a Z-Pak (azithromycin) due to an increased risk for QT prolongation and torsade de pointes (TdP).
QT prolongation and TdP have both been reported during post-marketing surveillance in patients receiving levofloxacin and azithromycin.
Due to the risk of the interaction, you should not take the drugs together without approval from your prescriber and it would be prudent to discuss possible alternative treatment options. If they are taken together, it is important to contact your prescriber immediately if you experience any of the following symptoms:
- Chest pain
- Dizziness
- Fainting
- Palpitations
- Shortness of breath
Safe To Take Levaquin After Azithromycin?
Azithromycin has an extremely long-half life and lasts in the body for a considerable amount of time after the last dose is taken. According to the prescribing information for azithromycin, the half-life is 68 hours.
Based on the half-life of azithromycin, below is an approximate concentration chart of azithromycin in your body relative to time after the last dose:
- One Half-life: 68 hours (~3 days): 50%
- Two Half-lives: 136 hours (~6 days): 25%
- Three Half-lives: 204 hours (~9 days): 12.5%
- Four Half-lives: 272 hours (~11 days): 6.25%
- Five Half-lives: 340 hours (~14 days): 3.125%
- Six Half-lives: 408 hours (17 days): 1.56%
As you can see, azithromycin has measurable concentrations in the body for a considerable amount of time.
One of the reasons that azithromycin has such a long half-life relative to other drugs is because of its extensive tissue concentrations.
The risk of drug interactions certainly decreases over time, but it can be difficult to completely avoid them if another drug needs to be added on quickly.
Although there is a risk of a drug interaction if Levaquin is started a few days after a Z-Pak, it isn't uncommon to do so if an additional antibiotic is needed.
It is just important to be aware of the potential side effects and reach out to your doctor if you experience any.
References
- Levaquin Prescribing Information. AccessFDA
- Azithromycin Prescribing Information. AccessFDA
- Clinical Relevance of Bacteriostatic versus Bactericidal Mechanisms of Action in the Treatment of Gram-Positive Bacterial Infections. Oxford Academic
- Antagonism between Bacteriostatic and Bactericidal Antibiotics Is Prevalent. American Society For Microbiology
- The pharmacodynamic properties of azithromycin in a kinetics-of-kill model and implications for bacterial conjunctivitis treatment. Springer Link
- Bactericidal mechanism of gatifloxacin compared with other quinolones. Oxford Academic
