Tetracycline Antibiotics

• The tetracycline antibiotics, including minocycline and doxycycline, have immunomodulatory and neuroprotective activities. They appear to decrease the passage of lymphocytes across the blood-brain barrier. A small Phase II 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 with 200 participants is studying the effect of 100 mg of oral minocycline twice daily on the conversion of clinically isolated syndrome (CIS) to a diagnosis of MS at six and 24 months. It began in January 2009 and is scheduled for completion in December 2015. It will determine whether 100 mg of oral minocycline twice daily reduces the conversion of clinically isolated syndrome (CIS) to clinically active MS and if any treatment benefit seen after six months is maintained at two years.
  
  
• 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.