Antibiotics can be an important line of defence against harmful bacteria, but a certain class of antibiotics may be dangerous for your heart, according to Canadian researchers.
Both conditions involve a backward flow of blood into the heart due to leakages in the valves. Mild or moderate sufferers can generally carry on with their lives with routine monitoring, but if it becomes severe, it can lead to palpitations, heart failure, and even death.
Fluoroquinolones offer resistance against a diverse range of bacterial infections like pneumonia, sinusitis and bronchitis. These drugs are also highly absorbent orally, meaning that pills can be as effective as IV treatment, making them a convenient alternative to a hospital stay.
This isn’t the first time that this drug class has been cited as dangerous. An FDA review suggested they can potentially cause a tearing of the aorta, and a 2013 report found that they could cause sudden, permanent nerve damage via peripheral neuropathy.
The authors of the present study were also critical of the liberal prescribing of fluoroquinolones because of the potential contribution to antibiotic resistance.
“[The study] adds to the existing list of serious adverse events with fluoroquinolones, underscoring the fact that these drugs shouldn’t be prescribed for uncomplicated community-acquired infections and should only be given when absolutely necessary,” said lead author Mahyar Etminan from the University of British Columbia, speaking to Healthline.
Elevated risk found up to 60 days after taking drug
Etminan and her colleagues sourced data from two sources: the US Federal Drug Administration’s adverse reporting system and US PharMetrics Plus, a large private insurance health claims database. Amongst a randomized sample of over nine million patients, they identified 12,505 cases of valvular regurgitation along with 125,020 control participants.
To control for confounding by infection, users of amoxicillin and azithromycin, two other types of antibiotics, were used for comparison. Both drugs have some crossover with fluoroquinolones in terms of the infections they target, like pneumonia and bronchitis.
Amoxicillin is a commonly prescribed, narrow-spectrum antibiotic which does not have an association with valvular regurgitation. Conversely, azithromycin is a broad-spectrum antibiotic used for mild to moderate bacterial infections. Both can be taken orally — amoxicillin absorbs rapidly in this regard, while azithromycin takes around 24 hours to catch up to the concentration levels of IV delivery.
Current exposure to fluoroquinolones (an active prescription or use within 30 days of the adverse event) was associated with the 2.4 times higher risk than amoxicillin users and 0.75 times higher versus azithromycin users.
Recent exposure (31 to 60 days since last use) still held a 1.47 times higher risk versus amoxicillin users and 1.37 against azithromycin users.
Past exposure (61 to 365 days since last use) did not seem to cause an elevated risk.
Authors hope to cultivate more cautious prescribing
The authors hope that future studies will drive home the idea that physicians should be more selective about prescribing fluoroquinolones given the growing evidence of risks. They also recommend that other antibiotic drugs become the go-to defence for uncomplicated infections.
“This study highlights the need to be thoughtful when prescribing antibiotics, which can sometimes cause harm,” said Bruce Carlton, Director of the Therapeutic Evaluation Unit in the UBC press release.
“As a result of this work, we will continue working with the BC Antimicrobial Stewardship Committee to ensure the appropriate prescribing of this class of antibiotics to patients across British Columbia, and reduce inappropriate prescribing.”