Allergic angioedema
In allergic angioedema, avoidance of the allergen and use of antihistamines may prevent future attacks. Cetirizine is a commonly prescribed antihistamine for angioedema. Some patients have reported success with the combination of a nightly low dose of cetirizine to moderate the frequency and severity of attacks, followed by a much higher dose when an attack does appear. Severe angioedema cases may require desensitization to the putative allergen, as mortality can occur. Chronic cases require steroid therapy, which generally leads to a good response.
Drug induced angioedema
ACE inhibitors can induce angioedema. ACE inhibitors block the enzyme ACE so that it can no longer degrade bradykinin; thus bradykinin accumulates and causes angioedema. This complication appears more common in African-Americans. In patients with ACE inhibitor angioedema, the drug needs to be discontinued and an alternate treatment needs to be found, such as an angiotensin II receptor blocker (ARB) which has a similar mechanism but does not affect bradykinin. However, this is controversial as there are small studies that have shown that patients with ACE inhibitor angioedema can develop it with ARBs as well.
Hereditary angioedema
In hereditary angioedema, specific stimuli that have previously led to attacks may need to be avoided in the future. It does not respond to antihistamines, corticosteroids, or epinephrine.
- Acute treatment
The aim of acute treatment is to halt progression of the edema as quickly as possible, which can be life-saving, particularly if the swelling is in the larynx. In Germany, most acute treatment consists of C1-INH concentrate from donor blood, which must be administered intravenously. In an emergency, fresh frozen blood plasma, which also contains C1-INH, can also be used. However, in most European countries, C1-INH concentrate is only available to patients who are participating in special programmes. Fresh frozen plasma (FFP) can be used as an alternative to C1-INH concentrate.
- Long-term prophylaxis
Patients in whom episodes occur at least once a month or who are at high risk of developing laryngeal edema require long-term prophylaxis. This often involves male sex hormones (androgens), which increase production of C1-INH in the liver through an as yet unknown mechanism. Danazol is the most commonly used. The dose should be kept as low as possible because of its frequent adverse effects. The use of androgens is particularly problematic in children and they must not be taken during pregnancy. Several cases in which patients developed benign liver tumours during treatment with danazol resulted in the substance being taken off the market in Germany at the beginning of 2005.
As an alternative, drugs known as fibrinolysis inhibitors, such as tranexamic acid, are used, although their effect is comparatively weak and their potential for side effects is questionable.
- Short-term prophylaxis
Short-term prophylaxis is normally administered before surgery or dental treatment. In Germany, C1-INH concentrate is used for this and given 1-11/2 hours before the procedure. In countries where C1-inhibitor concentrate is not available or only available in an emergency (laryngeal edema), high-dose androgen treatment is administered for 5–7 days.
- Long-term prophylaxis
In those with frequent or unpredictable attacks, regular infusions of plasma or inhibitor concentrate may be used. C1-INH concentrate is not available in the US, so sometimes fresh frozen plasma is used. C1inh concentrate is currently under late-stage development for both acute and prophylactic use.
- New treatment options
Clinical development of several new active substances, which intervene in the disease process in different ways, is currently ongoing.
Ecallantide is a peptide inhibitor of kallikrein that has received orphan status for HAE and has shown positive results in phase III trials.
Icatibant (marketed as Firazyr) is a selective bradykinin receptor antagonist, which has been approved in only Europe and not in the USA. After initial borderline results this drug was shown to be effective in phase III trials.
Pharming, a Dutch biotechnology company, is developing a recombinant C1 inhibitor for acute attacks of hereditary angioedema.
Cinryze has been approved by the FDA in October 2008
No studies have been done on these agents in relation to HAE type III.
Acquired angioedema
In acquired angioedema, HAE types I and II, and non-histaminergic angioedema, antifibrinolytics such as tranexamic acid or ε-aminocaproic acid may be effective. Cinnarizine may also be useful because it blocks the activation of C4 and can be used in patients with liver disease while androgens cannot[http://www.iaari.hbi.ir/journal/archive/articles/v4n3mor.pdf.
Further Reading
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