Corticosteroids for myasthenia gravis

Last updated Oct. 17, 2024, by Joana Carvalho, PhD
Fact-checked by Inês Martins, PhD

What are corticosteroids?

Corticosteroids are powerful anti-inflammatory medications that are widely used to reduce the activity of the immune system in inflammatory and autoimmune conditions such as myasthenia gravis (MG). By preventing the immune system from targeting healthy cells and tissues, these therapies help minimize inflammatory damage and ease disease symptoms.

There are many types of corticosteroids that can be used with MG and can be given orally or through other routes, based on medical need.

Anti-inflammatory corticosteroids are associated with a series of side effects, however, including weight gain, diabetes, high blood pressure, and mood changes, especially when administered at high doses for a prolonged period of time. For this reason, these medicines may not be recommended for people with certain conditions. A healthcare provider will take these factors into consideration when deciding if corticosteroids are appropriate for a specific patient.

When are corticosteroids used in MG?

Corticosteroids in myasthenia gravis are typically used in the long term to ease symptoms in people who responded poorly or had substantial side effects from first-line treatments.

These medicines were the first type of immunosuppressive agents to be widely adopted in treating MG and are considered the most effective oral immunosuppressants for this indication.

Treatment guidelines

According to the International Consensus Guidance for Management of Myasthenia Gravis, corticosteroids and/or nonsteroidal immunosuppressants should be used in all MG patients who fail to respond adequately to first-line treatment with pyridostigmine, which is sold as Mestinon and generics.

In patients who refuse treatment with corticosteroids, or for whom these medications are contraindicated, a nonsteroidal immunosuppressant should be used alone.

In turn, corticosteroids should be used alongside a nonsteroidal immunosuppressant when:

the risk of steroid side effects is high due to the presence of certain other conditions, or comorbidities
patients have significant steroid side effects
the response to corticosteroids is not adequate
the corticosteroid dosage cannot be reduced due to symptom reappearance.

A 2020 update to the international consensus guidance notes that corticosteroids should be the first immunosuppressive agents to be used in ocular MG, a disease type that exclusively affects the muscles controlling eye and eyelid movements. Clinical evidence indicates low-dose corticosteroids may be effective at controlling symptoms in these patients, avoiding side effects associated with high-dose corticosteroids. Still, nonsteroidal immunosuppressants may be required in these patients when corticosteroids alone are ineffective, contraindicated, or not well tolerated.

For patients who achieve their treatment goals with corticosteroids, the guidelines recommend their corticosteroid dose be gradually reduced. In many cases, however, remaining on a low-dose regimen of corticosteroids may be needed to maintain that treatment goal in the long term. Most patients will require some form of immunosuppressive treatment for many years, sometimes for life.

The guidelines also recommend that patients, even those receiving low doses, be routinely monitored for potential complications associated with long-term use of immunosuppressive therapies. If patients have substantial side effects or complications that impact their quality of life, changing to a different immunosuppressive agent should be considered.

How do corticosteroids work?

The most commonly used corticosteroids for myasthenia gravis belong to a subclass of therapies called glucocorticoids. These medications exert their anti-inflammatory and immunosuppressive effects by binding to glucocorticoid receptors inside a wide array of cells, including immune T-cells, macrophages, and neutrophils.

Once bound to these receptors, glucocorticoids trigger a series of effects, including a reduction in the production of pro-inflammatory signaling molecules and an increase in anti-inflammatory molecules. This switch favoring an anti-inflammatory environment is mainly driven by genomic mechanisms whereby the activated glucocorticoid-receptor complex binds to certain regions in the genome to regulate the activity of specific genes.

In addition to this genomic mechanism, which takes time to take effect, glucocorticoids can also exert immediate effects through nongenomic mechanisms. In this case, glucocorticoids activate receptors on the cell’s membrane, which can inhibit enzymes required for the production of pro-inflammatory molecules and suppress T-cell immune responses.

When administered at high doses, corticosteroids can also reduce the production of a variety of immune cell types (e.g., lymphocytes, macrophages, monocytes, eosinophils, and basophils), while also promoting their death via a mechanism called apoptosis.

Although corticosteroids are known for their broad inhibitory effects on the immune system, the precise mechanisms by which they work in the context of MG remains unclear. Some studies have indicated these medications may help lower the levels of self-reactive antibodies that drive MG, but others haven’t found an effect on antibody levels.

Benefits of corticosteroids

One of the main benefits of corticosteroids for myasthenia gravis is their effectiveness at easing disease symptoms. Another key advantage is their fast-acting mode of action, with clinical benefits being noticed within a few weeks.

Corticosteroids are considered to be the most effective oral immunosuppressive agents, with early clinical studies showing most MG patients see symptom remission or marked improvements in symptoms with long-term treatment.

Risks and side effects

Despite being highly effective, corticosteroids can cause notable side effects and complications, particularly when used at high doses over prolonged periods of time. Common corticosteroids side effects may include:

weight gain and increased appetite
mood changes
excessive hair growth
acne, easy bruising, and skin thinning
nervousness, restlessness, and difficulty sleeping
water retention and swelling
muscle weakness and fatigue
upset stomach
blurred vision.

Other notable risks associated with the use of corticosteroids include:

infections
diabetes
high blood pressure
bone loss (osteoporosis) and fractures
eye-related problems (cataracts and glaucoma)
gastrointestinal-related issues (indigestion, gastritis, and peptic ulcer disease).

Comorbidities that may be worsened by corticosteroid use should be closely monitored over the course of treatment.

Importantly, the specific side effects and risks of corticosteroids vary depending on the specific medication and the patient’s underlying health issues. These aspects will be considered by the person’s healthcare team when deciding if corticosteroids are appropriate.

Pregnancy and breastfeeding

Some immunosuppressants used in myasthenia gravis are considered teratogens, which means they can interfere with normal fetal development and result in birth defects or other serious health problems in newborn babies.

According to the U.S. Food and Drug Administration classification of teratogenic drugs, glucocorticoids that are commonly used to treat MG are classified as category C, indicating the risks to a developing fetus cannot be completely ruled out, even though available data doesn’t suggest these therapies are teratogenic.

However, glucocorticoids can increase a mother’s predisposition to develop high blood pressure and preeclampsia, a pregnancy complication marked by high blood pressure and organ damage, when administered at high doses. For this reason, there’s always the concern that the prolonged use of these medications during pregnancy can cause fetal toxicity or preeclampsia. It’s recommended that the dose of corticosteroids used during pregnancy be reduced to the lowest level possible.

Corticosteroids can pass into breast milk, so they should be used with caution in breastfeeding women. Patients should consult their doctor if they wish to breastfeed while using these medications.

Corticosteroids used in MG

There are several types of corticosteroids that can be used to treat MG. Some of them include:

prednisone (sold as Rayos, Prednisone Intensol, and generics), one of the most frequently used corticosteroids in MG patients. It’s available in several oral formulations, including tablets, delayed-release tablets, and an oral solution.
prednisolone (sold under many brand names, including Orapred ODT and Pediapred, and generics), the other corticosteroid that’s most commonly used in treating MG. It’s mostly available in oral forms, including tablets and syrup. It can be prescribed in patients with liver disease as an alternative to prednisone.
methylprednisolone (sold as Depo-Medrol, Medrol, Solu-Medrol, and generics), a corticosteroid that is similar to prednisolone and can also be used as an alternative to prednisone. It’s available in oral and injectable formulations.
dexamethasone (sold as Dexamethasone Intensol, Hemady, and several other brand names and generics), a medication with potent anti-inflammatory and immunosuppressive properties that’s particularly useful for treating MG associated with a thymoma, or a tumor in the thymus gland. It’s available in oral and injectable forms.
triamcinolone (sold as Triderm, Xipere, Triesence, and generics), a longer-acting corticosteroid that’s particularly effective for treating the initial symptoms of ocular MG. It’s sold in injectable and topical forms.

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