When I asked a few patients, “Is there anything what bothers you most having MG?” the answers were so consistent that I knew this was worth the time. “Having to take prednisone “ was almost universal. Understanding the use of corticosteroids is a critical aspect of treating MG and one for which every patient should have a clear sense.
Immunosuppressant therapy of some kind will be necessary in the majority of patients with many MG. Since the disease tends to be chronic, many MG patients also need to anticipate taking therapy for a long time. It can be argued that without immunosuppression, the immune system has an unopposed attack against the neuromuscular junction since Mestinon, when taken alone, treats only symptoms but does nothing to deter the autoimmunity.
Among the immune agents, corticosteroids and, in particular, prednisone, are arguably the most effective treatments. While there are few studies demonstrating effectiveness, years of experience have clearly taught us that this is a beneficial drug. Improvement usually begins within weeks of when high dose theraphy is initiated, (Prednisone 60mg a day) and it may even work within a few days in some. The vast majority will respond by several months. Note that no other drug has the profile of allowing patients to maintain a predictable and sustained recovery over the first few months after onset.
Despite being so effective, corticosteroids have an obvious downside in the variety of adverse effects associated with both short and long term use. Thus, the best medicine we have, by far, has significant limitations. This is a tough dilemma for the clinician which makes us all think hard about other options. It follows that whenever
someone begins Prednisone, the long term goal is to achieve stable recovery while
avoiding steroid related adverse effects. This requires eventually determining the minimal clinically effective dose and considering the use of second Prednisone-sparing drug if that dose is too high. The idea is to gradually replace prednisone with something that has fewer side effects and similar efficacy. While this cannot be done in the short run, there are several medications that can decrease the chances of being on prednisone in the long term. Medications in this category primarily include Azathioprine (Imuran), IV1G, Cyclosporine A, Cytoxan and Mycophenylate, Mofetil. The reader needs to be familiar with what we actually know.
Imuran is actually the best studied prednisone-sparing agent. In contrast and somewhat surprisingly. Imuran is not good at treating Myasthenia Gravis if used by itself as a first line agent. Moreover, the benefit as a prednisone-sparing agent does not accrue until the third year after beginning the medication. That means, even if a new Myasthenic goes on a combination of Imuran and Prednisone, it might take about three years to really increase the odds of getting off steroids. That means staying the course for a long time. It follows that there is a waiting period for Imuran to work, and it is possible that a patient has a few exacerbations (worsening) during this time. During these exascerbations, the clinician might temporarily increase Prednisone and then taper it off when the exascerbation resolves. This approach differs from switching from Imuran to something else, in the hope of having fewer exacerbations with time.
One other agent, CellCept, seems to have a reputation for being better than Imuran. While this impression is cautiously hopeful, the truth of the matter is we don’t actually know how to compare the agents, since there is only anecdotal information from a few uncontrolled studies. Knowledge of three key issues are lacking: how long it takes to start working, how well it works, and whether it can be used.
Myasthenia Gravis Association of British Columbia 