Pyridostigmine is seen as moderately effective in mitigating myasthenia gravis A study of Dutch patients revealed MG symptoms, but they are often accompanied by side effects.
The researchers note that the results do not indicate the need for changes to current guidelines, which recommend the use of pyridostigmine as a first-line treatment for MG.
“Our findings can be used to guide joint decision-making, prior to initiating symptomatic treatment of MG,” the researchers wrote.
Pyridostigmine (sold as Mystinon, among other brand names) is an oral medication often recommended as a first-line treatment for MG. It works by increasing the amount of acetylcholine, a signaling molecule that plays a key role in muscle contraction, and is available to bind to acetylcholine receptors – the most common targets of autoimmune attacks that It disrupts the communication between nerve and muscle in MG.
The treatment has been approved by the US Food and Drug Administration (FDA) since 1955 – before the advent of the modern concept of randomized controlled clinical trials. This is why the evidence supporting its use is largely based on retrospective data and clinical experience.
The researchers say the lack of objective data from well-controlled trials hinders understanding of the treatment’s efficacy and profile of side effects. Furthermore, the true effects of this ‘gold standard’ treatment must be determined in order to compare the efficacy of new and emerging treatments.
The authors sought to provide insight into this issue by comprehensively evaluating the use of pyridostigmine in a representative group of MG patients participating in the Dutch-Belgium Myasthenic Patient Registry. Participants were asked to fill out an online questionnaire regarding their use of pyridostigmine, their perceived effectiveness of treatment, and any side effects they experienced.
Of the 391 patients who completed the entire survey, 61% were currently using pyridostigmine, 37% had previously used the drug but had since stopped using it, and 2% had never used it.
“We show that nearly all MG patients have used pyridostigmine at some point in their disease,” the researchers wrote.
Most of them used a higher dose
Of the current users, 165 people (65%) reported having used a higher dose in the past. The most common reasons for reducing the dose were that a higher dose was no longer needed (43%), followed by side effects (25%), and the higher dose was not effective (17%).
Common reasons for stopping treatment were that it was ineffective (38%), or that it was unnecessary because another treatment was started (34%). About a quarter (26%) of patients discontinued its use due to side effects. Medications have been used to help control the side effects of pyridostigmine in 20% of all patients.
Patients rated the effectiveness of pyridostigmine on a scale ranging from 0 (no therapeutic effect) to 100 (complete resolution of all symptoms). The average overall effectiveness was 60 out of 100, with patients currently using pyridostigmine finding the treatment to be more effective than those who stopped using it.
By individual symptoms, fatigue was the least responsive to treatment in both groups.
In the current use group, 55% of participants reported that the effects of treatment did not change over time, compared to 21% of those who stopped treatment. For patients who discontinued pyridostigmine, 23% said the initial effect was good but diminished over time, while 12% said increased doses were required over time to achieve the same effect.
Most patients using pyridostigmine (91%) said they had experienced side effects in the past week, compared to 54% who stopped taking it or never used it. Side effects, including gastrointestinal problems, urinary urgency, muscle cramps, blurred vision, sweating, drooling, light-headedness, and flu-like symptoms were more common among current pyridostigmine users than other survey participants.
Unpleasant side effects
Among current users, the number of side effects was related to the dose of the drug. Diarrhea was the most common reason for stopping or decreasing the dose of pyridostigmine.
Taking into account the perceived benefits and side effects, patients reported an average net benefit of pyridostigmine from 65 on a scale from 0 (“I felt much worse”) to 100 (“I felt much better”), with current users reporting an average of 73. , and discontinued users with an average of 49.
Final statistical analyzes indicated that patients with a tyrosine kinase (MuSK) antibody were more likely to discontinue pyridostigmine, consistent with previous findings that pyridostigmine was less effective and had more side effects in patients with this type of musk. MG-causing antibodies.
Male users were more likely to discontinue treatment than females, the researchers wrote, “which may be explained by the fact that female patients often have severe or refractory MG and male patients appear to respond better to standard care than female patients.”
Female patients frequently reported side effects, including fatigue, sweating, abdominal cramps, hot flashes, and irregular heartbeat.
Overall, the study results indicate that the net benefit from pyridostigmine is moderate, and that side effects are frequent.
“Remarkably, only a small number of patients experienced a very good effect of pyridostigmine on their symptoms,” the researchers wrote. “However, pyridostigmine remains a readily available drug at low cost with very favorable long-term safety properties.”
The researchers developed a patient-friendly handout summarizing the results that they say can be distributed when a prescription for pyridostigmine is given.