Acthar Gel (repository corticotropin injection) is a prescription medication approved by the FDA to treat a range of inflammatory and autoimmune conditions. It is used most commonly for infantile spasms in babies, acute relapses of multiple sclerosis, nephrotic syndrome, rheumatic disorders like lupus, and several other conditions where the body’s immune system drives damaging inflammation.
How Acthar Works
Unlike standard steroids such as prednisone, which deliver a synthetic hormone directly into your system, Acthar takes an indirect route. It contains a naturally sourced mixture of purified ACTH (adrenocorticotropic hormone) analogs and other pituitary peptides derived from porcine (pig) pituitary glands. When injected, these peptides activate a receptor on the adrenal glands that triggers your body to produce its own cortisol and other anti-inflammatory hormones.
Acthar also appears to fight inflammation through a second pathway that has nothing to do with cortisol. The peptides in Acthar bind to receptors found directly on immune cells, dampening the inflammatory response at the cellular level. This dual mechanism, stimulating your body’s own steroid production while also acting on immune cells independently, is what distinguishes Acthar from a straightforward corticosteroid prescription.
Infantile Spasms
Infantile spasms (also called West syndrome) are a serious seizure disorder that typically appears in babies during the first year of life. Acthar is one of the primary treatments and is given as an intramuscular injection twice daily at a dose based on body surface area, typically over a two-week treatment period. After those two weeks, the dose is gradually tapered over another two weeks to prevent adrenal insufficiency, a condition where the body’s natural hormone production stalls after being supplemented externally.
Acthar is not used in infants under two years old who have suspected congenital infections, as the immune-suppressing effects could worsen those conditions.
Multiple Sclerosis Relapses
Acthar is approved for acute exacerbations of multiple sclerosis, the sudden flare-ups where symptoms like vision loss, numbness, or difficulty walking intensify. The typical course involves daily injections of 80 to 120 units, given either intramuscularly or subcutaneously, for two to three weeks. It is not a maintenance therapy for MS. Its role is limited to calming the acute inflammatory episode and helping the patient recover from a relapse more quickly.
Nephrotic Syndrome
Nephrotic syndrome is a kidney condition where damaged filters in the kidneys leak large amounts of protein into the urine. In a clinical study of adults with idiopathic membranous nephropathy (one form of nephrotic syndrome), patients who received Acthar for three to six months saw a 60% response rate, meaning their protein leakage either resolved completely or dropped by more than half. Only 5% showed no response at all, while 35% continued to have persistent symptoms. Complete remission was defined as protein in the urine dropping below 0.3 grams per day.
Rheumatic and Autoimmune Conditions
Acthar is FDA-approved for several rheumatic disorders, including rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis. In these conditions, it is generally reserved for flare-ups or for patients who haven’t responded well to first-line treatments. It is also approved for systemic lupus erythematosus (lupus), where it can help manage the widespread inflammation that affects the joints, skin, kidneys, and other organs.
For these conditions, Acthar typically serves as a short-term intervention to bring a flare under control rather than as a long-term daily medication.
Other Approved Uses
Beyond the conditions above, Acthar carries FDA approval for a broad range of inflammatory and allergic disorders:
- Eye inflammation: Severe allergic and inflammatory conditions affecting the eye, such as uveitis and optic neuritis
- Respiratory conditions: Symptomatic sarcoidosis and certain cases of severe asthma
- Skin conditions: Severe psoriasis, severe erythema multiforme, and other dermatologic diseases
- Adrenal testing: Diagnostic testing of adrenocortical function
- Collagen diseases: Dermatomyositis and systemic dermatomyositis
In most of these cases, Acthar is positioned as an option when conventional therapies have failed or are not appropriate.
How It Is Given
Acthar is injected either into the muscle (intramuscular) or just under the skin (subcutaneous), depending on the condition being treated. For infantile spasms, only the intramuscular route is used. For most adult conditions, either route is acceptable. Patients or caregivers are typically trained to administer the injections at home. The gel formulation is designed to release the active peptides slowly, providing a longer duration of action than a standard injection.
Side Effects and Risks
Because Acthar stimulates cortisol production and suppresses immune function, its side effect profile overlaps significantly with that of corticosteroids. In clinical studies of infantile spasms, the two most common serious side effects were infections (7.4% of patients) and high blood pressure (8.2%). Other less frequent but potentially serious effects included low potassium levels, high blood sugar, and heart muscle problems.
Everyday side effects can include fluid retention, weight gain, mood changes, and increased appetite, similar to what patients experience on oral steroids like prednisone. The longer the treatment course, the higher the risk of these effects becoming significant.
Who Should Not Use Acthar
Acthar is not appropriate for everyone. It is contraindicated in people with osteoporosis, uncontrolled high blood pressure, congestive heart failure, systemic fungal infections, scleroderma, or a history of peptic ulcers. People with primary adrenal insufficiency (where the adrenal glands don’t function properly) or adrenal hyperfunction should also avoid it, since the drug works by stimulating those glands. Patients who are sensitive to porcine-derived proteins cannot use Acthar, and live vaccines should not be given during treatment because of the drug’s immunosuppressive effects.
Acthar should never be given intravenously. It is formulated strictly for intramuscular or subcutaneous injection.