Hereditary Angioedema Prophylaxis

Introduction to Prophylaxis

The American Academy of Allergy, Asthma, and Immunology recommends short-term prophylaxis for patients undergoing procedures or experiencing predictable triggers, while long-term prophylaxis is indicated for patients with frequent, severe attacks that significantly impact quality of life 1, 2

Short-term prophylaxis is indicated for predictable upcoming stressors, such as dental procedures, particularly extractions, and invasive medical or surgical procedures, especially those involving the head and neck region 1, 2, 3
Medication options for short-term prophylaxis include C1 inhibitor replacement therapy, attenuated androgens, fresh frozen plasma, and tranexamic acid, with specific dosing recommendations for each 1, 2, 4, 5
The American College of Allergy, Asthma, and Immunology suggests that short-term prophylaxis should be administered before the procedure to prevent attacks, with plasma-derived C1INH preferred for emergency procedures 1, 2, 6

Long-term prophylaxis should be individualized based on attack frequency and severity, location of attacks, access to acute care, comorbid conditions, and patient preference 2, 7
Medication options for long-term prophylaxis include C1 inhibitor replacement therapy, attenuated androgens, and antifibrinolytic agents, with specific dosing recommendations for each 7, 8, 9

For children, fresh frozen plasma and tranexamic acid are preferred for short-term prophylaxis, while tranexamic acid is preferred over androgens for long-term prophylaxis due to concerns about growth and development 4, 5
During pregnancy, C1INH is the only recommended treatment for both acute attacks and prophylaxis, while androgens are contraindicated 4, 5

Regular monitoring for side effects is necessary for androgen therapy, with periodic hepatic ultrasounds and blood tests 4, 9
Dose adjustments for long-term prophylaxis with androgens should start with either high or low dose and titrate to the lowest effective dose, with changes in dosage not occurring more frequently than once per week 10

C1 esterase inhibitor replacement therapy is FDA-approved for prophylaxis in type 1 HAE, with a recommended starting dose of 1000 U every 3-4 days, and has demonstrated significant reduction in attack frequency in long-term studies, according to the American Academy of Allergy, Asthma, and Immunology 11, 12, 13
Plasma-derived C1INH has shown a significant reduction in attack frequency, from a median of 3 attacks per month to less than 1 attack per 5 months, in patients with type 1 HAE, as recommended by the American College of Allergy, Asthma, and Immunology 13

Attenuated androgens, such as danazol, can be effective in both type 1 and type 2 HAE, but are generally considered second-line due to side effects, and should be started at a low dose and titrated to the lowest effective dose, as suggested by the American Academy of Allergy, Asthma, and Immunology 14
Antifibrinolytic drugs like tranexamic acid and epsilon aminocaproic acid provide somewhat effective prophylaxis, but are generally less effective than androgens or C1-INH replacement, according to the American College of Allergy, Asthma, and Immunology 11

The dose and effectiveness of prophylaxis should be based on clinical criteria, such as attack frequency and severity, rather than laboratory parameters, as recommended by the American Academy of Allergy, Asthma, and Immunology 13
Patients receiving prophylactic C1-INH still experience breakthrough attacks, requiring on-demand treatment to be readily available, according to the American College of Allergy, Asthma, and Immunology 11

Relying on standard angioedema treatments like epinephrine, corticosteroids, or antihistamines, which are ineffective for HAE attacks, as stated by the American Academy of Allergy, Asthma, and Immunology 15
Failing to adjust prophylactic dosing based on clinical response rather than laboratory values, as recommended by the American College of Allergy, Asthma, and Immunology 13