Multiple Sclerosis Diagnosis Delayed by Antibiotic

Minocycline can reduce risk of conversion over 6 months of treatment.

Minocylcine was proven to reduce the risk of a clinically isolated syndrome (CIS) converting to multiple sclerosis (MS) over a short period of treatment, according to a recent Canadian study.

The tetracycline antibiotic treatment commonly associated with skin condition uses was tested on patients within 180 days of their first experiencing a CIS, or demyelinating event. Demyelination is better defined as damage to the myelin sheath of neurons, which weakens the effected nerves’ signaling and limits nerve-based function such as cognition.

Lead by Luanne Metz (pictured), MD, FRCPC, professor and head of the Division of Neurology in the Department of Clinical Neurosciences at the University of Calgary, researchers followed “encouraging preliminary results” to the efficacy study of minocycline against MS conversion.

Participants were either assigned to a fixed dosage minocycline treatment or placebo group from a trial period between January 2009 and July 2013. Patients were required to have experienced their first CIS — which could eventually lead to MS diagnosis — within 180 days of entering the trial. The randomized, controlled trial administered 100 mg of minocycline orally twice daily to one patient group, and equal dosage placebo treatment to the other.

Administration of treatment was continued in each patient until they either were diagnosed with MS, or until 24 months after randomization — whichever came first. The primary outcome of the trial was conversion to multiple sclerosis within 6 months after randomization. Diagnoses of MS were based on the 2005 McDonald Criteria.

Secondary outcomes for the trial included diagnosed conversion to MS within 24 months after randomization and changes in combined lesions and lesion sizes, as per magnetic resonance imaging (MRI).

The trial included 142 patients from 12 Canadian MS clinics, randomized almost evenly between the 2 treatment groups. While 72 patients were assigned to receive minocycline, 70 were assigned to receive placebo.

The unadjusted risk of conversion to multiple sclerosis within 6 months following randomization was 61% in the placebo group, versus just 33.4% in the minocycline group. That 27.4% difference was reduced by less than 10% when adjusted for the number of patients’ enhancing lesions at baseline.

Minocycline was favored in all secondary MRI outcomes versus placebo at the 6-month time point, but not at 24 months. The trial also did not report a significant risk difference between the 2 treatment groups at the 24-month time point.

Additionally, trial withdrawals and adverse events such as rash, dizziness, and dental discoloration were more frequent among minocycline patients versus placebo patients.

Researchers concluded that minocycline was significantly more efficient in preventing CIS conversion to MS in patients over 6 months of treatment versus placebo, but not over the span of 24 months.