Management of Hereditary Angioedema

Acute Attack Management

• The American Academy of Allergy, Asthma, and Immunology recommends plasma-derived C1 inhibitor concentrate as the most effective first-line treatment for acute HAE attacks, administered at a dose of 1000-2000 U intravenously 1, 2
• Early treatment is critical, and on-demand treatment is most effective when administered as early as possible during an attack, with the goal of reducing the duration and severity of symptoms 1, 3
• All patients with HAE should have access to an effective on-demand HAE-specific agent and a contingency plan for management of acute attacks, including a plan for emergency procedures and airway management 3
• Laryngeal attacks should be observed in a medical facility capable of performing intubation or tracheostomy if necessary, with close monitoring for signs of impending airway closure, such as change in voice, loss of ability to swallow, or difficulty breathing 3, 4
• Standard angioedema treatments, including epinephrine, corticosteroids, and antihistamines, are not effective for HAE attacks and should not be used as first-line treatment 4, 2

Prophylactic Treatment

• Short-term prophylaxis is indicated before dental work, surgical procedures, or invasive medical procedures, with plasma-derived C1INH as the first-line option, administered at a dose of 1000-2000 U or 20 U/kg for children 3, 1
• Long-term prophylaxis should be considered for patients with frequent or severe attacks, with plasma-derived C1INH and lanadelumab as first-line options, and attenuated androgens and antifibrinolytic agents as second-line options 2, 5
• Anabolic androgens should be initiated at either high or low dose and then slowly titrated to the lowest effective dose, with dosage adjustments not made more frequently than once per week 3

Special Considerations

• During pregnancy, pdhC1INH is recommended as first-line therapy for both acute attacks and prophylaxis, with antifibrinolytics as an alternative option for mild attacks if pdhC1INH is unavailable 6
• Anabolic androgens should be discontinued at least 2 months before attempting conception due to the risk of fetal abnormalities, and close follow-up by staff familiar with HAE is recommended for at least 72 hours after delivery 6

Common Pitfalls to Avoid

• Delaying treatment of acute attacks, especially those involving the airway, can lead to increased morbidity and mortality, and should be avoided whenever possible 3, 4
• Using standard angioedema treatments, such as antihistamines, corticosteroids, and epinephrine, which are ineffective for HAE, can lead to delayed diagnosis and treatment, and should be avoided 4, 2

Global Access Considerations

• Significant disparities exist in HAE management resources between high-income and low-income countries, with first-line treatments often unavailable in low-income countries, and efforts should be made to improve global access to effective HAE treatments 5, 7, 8

Treatment of Hereditary Angioedema

Acute Attack Management

• Ecallantide (plasma kallikrein inhibitor) and recombinant human C1INH concentrate (rhC1INH) are effective for acute attacks, though ecallantide must be administered by a healthcare professional due to anaphylaxis risk 9, 10

Treatment Based on Attack Location

• Peripheral attacks (extremities, face) should receive prompt treatment rather than a "wait-and-see" approach, as early intervention prevents avoidable pain and reduces disruption to the patient's life 11, 12

Common Pitfalls to Avoid

• Failing to recognize that laryngeal attacks are potentially life-threatening with historical mortality rates of approximately 30% 13

Global Access Considerations

• Significant disparities exist in HAE management resources between high-income and low-income countries 13
• In resource-limited settings where first-line treatments are unavailable, fresh frozen plasma (10-15 ml/kg) may be considered for acute attacks 13
• Tranexamic acid and attenuated androgens may be used for prophylaxis in settings where first-line agents are not available 13

Self-Administration and Home Treatment

• Ecallantide requires healthcare professional administration due to anaphylaxis risk 9

Appropriate Use of Danocrine (Danazol) in Hereditary Angioedema

Indications for Danazol in HAE

• Danazol is particularly valuable in resource-limited settings where first-line therapies are unavailable, and is considered a second-line option for long-term prophylaxis after plasma-derived C1INH and lanadelumab 14, 15

Contraindications and Special Populations

• Danazol is contraindicated during pregnancy and breastfeeding due to potential teratogenic effects and risk of masculinizing the female fetus, and should be discontinued at least 2 months before attempting conception 16
• Danazol should generally be avoided in children before Tanner Stage V of puberty due to potential effects on growth and development 16

Important Considerations

• Danazol is not effective for treating acute HAE attacks - it is only for prophylaxis, and for acute attacks, plasma-derived C1INH, icatibant, or ecallantide are recommended first-line treatments 17
• Standard angioedema treatments (antihistamines, corticosteroids, epinephrine) are ineffective for HAE attacks and should not be used 17

Alternative Prophylactic Options

• Tranexamic acid may be considered as an alternative prophylactic agent when first-line treatments and danazol are unavailable or contraindicated 15