Tetracycline treatment in patients with progressive external ophthalmoplegia

Background - Tetracyclines could have neuroprotective effects in neuromuscular and neurodegenerative disorders. Aims of the study and methods - Objective of this double-blind randomized pilot study (followed by an adjunctive open-label phase) was to evaluate whether tetracycline (500 mg/day x 14 days/month x 3 months) could be useful in patients (n = 16) with progressive external ophthalmoplegia (PEO). Results - Our results do not formally support any effect of tetracycline on eye motility in PEO. However, some possible protective effects could not be completely ruled out, i.e. a further analysis suggests a possible difference between the tetracycline group and the placebo group, significant at least for oblique motility, when comparing the ratio between the end of the double-blind phase and baseline. Tetracycline could modify some oxidative stress biomarkers in patients with PEO. Conclusions - Further studies are needed to confirm such effects of tetracycline in patients with PEO, if any, and to clarify the mechanisms of action for antioxidant effects of tetracyclines in mitochondrial disorders and other diseases.