What are the treatment options for Mast Cell Activation Syndrome (MCAS)?

From the Guidelines

The treatment of Mast Cell Activation Syndrome (MCAS) should prioritize a multi-faceted approach focusing on symptom management and trigger avoidance, with first-line medications including H1 antihistamines, H2 antihistamines, and mast cell stabilizers, as recommended by the 2019 report from the aaaai mast cell disorders committee work group 1. The treatment approach involves a combination of pharmacologic agents and lifestyle modifications.

• First-line medications include:
  • H1 antihistamines, such as nonsedating H1 histamines, which can be increased to 2 to 4 times the standard dose 1
  • H2 antihistamines, which can be used as first-line therapy for gastrointestinal symptoms and might help H1R antihistamines attenuate cardiovascular symptoms 1
  • Cromolyn sodium, which can reduce abdominal bloating, diarrhea, and cramps, and might extend to neuropsychiatric manifestations 1
• Additional treatment options include:
  • Doxepin, a potent H1 & H2 antihistamine with tricyclic antidepressant activity, which might reduce central nervous system manifestations in patients with MCAS or SM 1
  • Aspirin, which might reduce flushing and hypotension in some patients, particularly those with increased urinary 11b-PGF2a levels 1
  • Steroid taper/steroid burst, which might be useful for refractory signs or symptoms 1
  • Omalizumab, which might prevent anaphylactic episodes in some patients with MCAS or SM 1
• Lifestyle modifications include:
  • Avoidance of known triggers, such as certain foods, temperature extremes, alcohol, NSAIDs, stress, and physical exertion 1
  • Supine positioning for patients with recurrent hypotensive episodes 1
  • Use of an epinephrine autoinjector for patients with a history of systemic anaphylaxis or airway angioedema 1 It is essential to note that treatment effectiveness varies among patients, and medication regimens often require personalization through trial and error 1.

From the FDA Drug Label

Four randomized, controlled clinical trials were conducted with Cromolyn Sodium Oral Solution (Concentrate) in patients with either cutaneous or systemic mastocytosis; two of which utilized a placebo-controlled crossover design, one utilized an active-controlled (chlorpheniramine plus cimetidine) crossover design, and one utilized a placebo-controlled parallel group design Clinically significant improvement in gastrointestinal symptoms (diarrhea, abdominal pain) were seen in the majority of patients with some improvement also seen for cutaneous manifestations (urticaria, pruritus, flushing) and cognitive function The benefit seen with Cromolyn Sodium Oral Solution (Concentrate) 200 mg QID was similar to chlorpheniramine (4 mg QID) plus cimetidine (300 mg QID) for both cutaneous and systemic symptoms of mastocytosis.

Treatment options for Mast Cell Activation Syndrome (MCAS) may include:

• Cromolyn Sodium Oral Solution (Concentrate) 200 mg QID
• Chlorpheniramine 4 mg QID plus cimetidine 300 mg QID These options have shown clinical improvement in gastrointestinal and cutaneous symptoms of mastocytosis, a condition related to MCAS, within 2-6 weeks of treatment initiation 2.

From the Research

Treatment Options for Mast Cell Activation Syndrome (MCAS)

The treatment options for MCAS include:

• Avoiding triggers 3
• Modulating mast cell activation and the effects of the mediators 3
• Using over-the-counter medications to modulate mast cell activation 3
• H1-antihistamines to block the effects of histamine released by mast cells 4, 5, 6
• H2-antihistamines to block the effects of histamine released by mast cells 4, 5
• Leukotriene receptor blockade to block the effects of leukotrienes released by mast cells 5
• Inhibition of mediator synthesis using aspirin or zileuton 5
• Mediator release inhibition using sodium cromolyn 5
• Anti-IgE therapy 5
• Epinephrine for acute episodes of mast cell activation 5
• Corticosteroids for prolonged episodes of mast cell activation 5

Stepwise Treatment Approach

A stepwise treatment approach is often used, with a combination of drugs necessary to achieve symptom control 6. The treatment approach may involve:

• Blocking the effects of mediators released by mast cells on activation 6
• Using a combination of drugs to achieve symptom control 6
• Tailoring the treatment approach to the individual patient's needs 6

Response to Treatment

The response to treatment can vary, with some patients experiencing:

• Complete resolution of symptoms 6
• Major response to treatment 6
• Minor response to treatment 6