Fluoxetine: Tolerated but Questionable Efficacy for Acute Flaccid Myelitis

Fluoxetine, a selective serotonin reuptake inhibitor with antiviral activity, is well tolerated but not effective for improving neurologic outcome in patients with enterovirus D68-associated acute flaccid myelitis (AFM), according to observational study results published in Neurology.

In this multicenter study, researchers compared serious adverse events, adverse effects, and outcomes between fluoxetine-treated patients with AFM (n=28) vs untreated control participants (n=28). The administration of fluoxetine occurred at the providers’ discretion, and the investigators retrospectively reviewed de-identified patient data to compare outcomes. Change in summative limb strength score (SLSS; sum of Medical Research Council strength in all 4 limbs, ranging from 20 [normal strength] to 0 [complete quadriparesis]) from the initial examination to the latest follow-up comprised the primary outcome. For this analysis, an increased SLSS and decreased SLSS indicated improvements and worsening in strength, respectively.

Data from 56 patients with AFM from 12 centers met the inclusion criteria for analysis. No serious adverse events were reported in the patients who received fluoxetine. In addition, no difference was determined between the fluoxetine-treated and untreated control patients in terms of adverse effect rates (47% vs 65%, respectively; P =.16). Patients who received >1 fluoxetine dose were more likely to have enterovirus D68 identified compared with untreated control participants (57.1% vs 14.3%, respectively; P <.001).

In addition, fluoxetine-treated patients had similar mean SLSS at both the initial assessment (12.9 vs 14.3; P =.31) and last follow-up (12.5 vs 16.4; P =.005). The mean SLSS was lower at nadir in patients treated with fluoxetine (9.25 vs 12.82; P =.02). The SLSS from initial assessment to last follow-up decreased by 0.2 (95% CI, −1.8 to 1.4) and increased by 2.5 (95% CI, 0.7 to 4.4) in fluoxetine-treated and untreated patients, respectively (P =.015).

Despite recruiting from multiple centers, the small number of participants in the final cohort represents a possible limitation of the study.

In conclusion, the investigators added that their “data, coupled with recent animal model data, do not suggest a positive efficacy signal for fluoxetine as a potential antiviral therapy for AFM.”

Reference

Messacar K, Sillau S, Hopkins SE, et al. Safety, tolerability, and efficacy of fluoxetine as an antiviral for acute flaccid myelitis [published online November 9, 2018]. Neurology. doi: 10.1212/WNL.0000000000006670