Tetracycline Antibiotics

• The tetracycline antibiotics, including minocycline and doxycycline, have immunomodulatory and neuroprotective activities. They appear to decrease the passage of leukocytes across the blood-brain barrier. An earlier trial of Copaxone plus minocycline showed favorable MRI data.
  
  
• In a small trial in patients with RRMS, minocycline decreased gadolinium-enhancing activity by 50 percent over a period of six months. A subsequent 24-month trial showed a significant decrease in lesion activity and clinical status.
  
  
• A Phase III trial that began in 2008 is studying the effect of 100 mg of oral minocycline twice daily on the conversion of CIS to a diagnosis of MS at six and 24 months.
  
  
• A small Phase IIa study with 45 patients will study minocycline in acute optic neuritis (ON). It began in February 2010, and is scheduled for completion in February 2013. The primary aim of this open-label pilot trial is to estimate the treatment effect of 100 mg of oral minocycline twice daily for 90 days, initiated within 30 days of onset of ON. The study will evaluate the effects on functional and structural optic nerve recovery compared to no treatment. The primary outcome measure will be the degree of optic nerve recovery, as measured by the retinal nerve fiber thickness.
  
  
• A small Phase IV study combining doxycycline with Avonex demonstrated a statistically significant reduction of gadolinium-enhancing lesions compared with Avonex alone. A larger trial is needed to confirm these results.