Fluoroquinolone-associated myasthenia gravis exacerbation: evaluation of postmarketing reports from the US FDA adverse event reporting system and a literature review.

BACKGROUND

Exacerbations of myasthenia gravis have been reported in antibacterial-treated patients. In animal and in vitro models of experimentally-induced myasthenia gravis, fluoroquinolones exhibit neuromuscular blockade.

OBJECTIVE

The aim of this retrospective study was to evaluate postmarketing adverse event reports submitted to the US FDA and case reports published in the scientific literature for a potential association between fluoroquinolone exposure and acute exacerbations of myasthenia gravis.

METHODS

On 1 March 2011, we searched the FDA Adverse Event Reporting System (AERS) database to retrieve all reports of myasthenia gravis exacerbation as a serious adverse event in patients treated with fluoroquinolones. We also conducted an Internet-based search using EMBASE for additional English-language cases in the scientific literature.

RESULTS

We identified a total of 37 unique cases describing myasthenia gravis exacerbation following fluoroquinolone systemic exposure. We retrieved AERS reports for 27 non-ventilated patients administered the following fluoroquinolones: levofloxacin (n = 9), moxifloxacin (n = 6), ciprofloxacin (n = 6), ofloxacin (n = 2), gatifloxacin (n = 2), norfloxacin (n = 1) and trovafloxacin (n = 1). Additionally, we retrieved ten case reports published in the literature involving non-ventilated patients administered ciprofloxacin (n = 4), levofloxacin (n = 2) and ofloxacin, norfloxacin, pefloxacin and prulifloxacin (1 patient each). Myasthenia gravis exacerbations developed a median of 1 day following fluoroquinolone exposure. The 37 cases describe dyspnoea (n = 19; 51%), myasthenic crisis requiring ventilatory support (n = 11; 30%) and death (n = 2; 5%). Additional exacerbation-related adverse events were generalized muscle weakness (n = 20; 54%), dysphagia (n = 9; 24%), diplopia (n = 6; 16%) and ptosis (n = 6; 16%). Six patients (16%) experienced a positive rechallenge, with recurrent myasthenia gravis exacerbation after fluoroquinolone reintroduction.

CONCLUSIONS

Fluoroquinolone exposure may result in potentially life-threatening myasthenia gravis exacerbations in patients with underlying disease. Healthcare professionals should be aware of this serious drug-disease association and carefully weigh the benefit-risks of fluoroquinolones when treating infections in non-ventilated myasthenic patients.