Background: Multiple sclerosis (MS) is an immune-mediated inflammatory disease
that attacks myelinated axons in the central nervous system, destroying the myelin and the
axon in variable degrees and causing significant disability in many patients. Neuro-Myelitis
Optica Spectrum Disorder (NMOSD) is a rare disorder that was considered a subtype of MS
but is now recognized as a distinct demyelinating disorder that affects mainly the spine and
Objective: The present paper is a review of the recent knowledge regarding present and new
drugs that have been recently added to the therapeutic arsenal for MS as well as those which
seem to be beneficial for patients with NMOSD.
Methods: A step-by-step description of the evolving drug arsenal is presented for both MS and
Neuro-Myelitis Optica Spectrum Disorder (NMOSD).
Results: Modern drug therapy for MS started with the introduction of ACTH (Adrenocorticotropic
hormone) and somewhat later was followed by high dose corticosteroids for treatment
of the neurological deficits during an acute relapse. This mode of treatment, which became
popular during the years 1970-1980 failed to reduce the number of relapses or to affect the
outcome of the disease. Only during the last two decades, the field of MS drug therapy underwent
a remarkable change from simple amelioration of symptoms of an acute attack to the
development of numerous Disease Modifying Treatments (DMTs). The formulation of DMTs
evolved from the older inconvenient subcutaneous or intramuscular route of administration to
oral preparations or periodic intravenous infusions of biological drugs. A new treatment was
approved in 2017 for reducing disease progression rate for the first time in primary progressive
Besides MS, progress was made in delineating the pathophysiology of NMOSD, a devastating
demyelinating disorder that is still frequently confused with MS.
Although beneficial, the new treatment modalities carry with them adverse effects that may be
serious and even life threatening. With the increase in the usage of those drugs, the spectrum
of the reported adverse effects is expanding and calls for additional research in regard to the
safest way of their utilization.
Conclusion: Targeting the immune system in general in RRMS and NMOSD and even PPMS
has proven successful, with efficacy varying based on the specific treatment. There are still
unmet needs for medications that will address safety and efficacy altogether and prevent disability
Areas Covered: The mode of action and main characteristics and side effects of current DMTs
for both MS and NMOSD and their place in the therapeutic algorithm of both diseases based
on updated evidence from clinical trials.