Angioedema of the upper airways requires a well-coordinated diagnostic and therapeutic approach. Steroids and antihistamines are very effective against mast-cell-mediated angioedema, but nearly useless against bradykinin-mediated angioedema. For angioedema induced by ACE inhibitors, no causally directed treatment has yet been approved.

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Background: Hereditary angioedema (HAE) patients suffer from recurrent swellings. Current standard therapy consists of C1 esterase inhibitor (C1-INH) and bradykinin receptor B2 antagonists. Severe courses require prophylactic treatment. For such patients, it has been demonstrated that the intravenous (IV) administration of C1-INH [C1-INH(IV)] is safe and effective. A new prophylactic option is subcutaneous (SC) treatment with C1-INH. Methods and Case: We present the case of an HAE patient placed on prophylactic C1-INH(IV) therapy due to frequent attacks when managed with on-demand therapy. An implanted port allowed the periodical and safe application of medication until the device was explanted due to an infection. Due to the poor venous access, repeated IV application failed. Therefore, we began a SC treatment with 1500 IU C1-INH [C1-INH(SC)] as long-term prophylaxis and analyzed the clinical course over 16 months. Results: Under the SC prophylaxis, the number of attacks were reduced to 1/month in comparison to 4.33/month with no prophylactic treatment and 1.83/month with C1-INH(IV). No severe attacks and no attack within the upper airway occurred over the 16 months of C1-INH(SC) treatment. As a result, quality of life improved, as measured by the Angioedema quality of life questionaire (AE-QoL). Conclusion: Self-administered SC prophylactic use of C1-INH over a period of 16 months seems to be a well tolerated and efficient. The patient’s quality of life improved, and by learning self-application, the patient gained independence.

Aims: Angioedema is a rare side effect of angiotensin-converting enzyme (ACE) inhibitors. It remains unclear why it is only induced in a few patients taking ACE inhibitors, often after a long period of uneventful treatment. The aim of this study was to analyze the influence of ACE inhibitor treatment on C1-inhibitor (C1-INH) levels. Methods: Captopril (5 mg/25 mg) was added to blood samples of 5 healthy subjects. C1-INH levels were measured before and after incubation for 180 min. The second section of the study was done with 17 patients who received therapy with an ACE inhibitor for the first time. C1-INH levels were measured before ACE inhibitor treatment, 24 h after first drug administration, and 4 weeks later. Results: After incubation of blood samples with 5 mg captopril, there was no detectable change in C1-INH levels. After incubation with 25 mg, C1-INH activity was decreased by an average of 29% and the C1-INH concentration was decreased by an average of 0.06 g/L. In the second study section, inconsistent effects on C1-INH levels were detected. In the majority of patients, 24 h after the first ACE inhibitor administration C1-INH activity was tending to be increased. Conclusions: A dose-dependent effect on C1-INH levels in captopril-incubated blood samples of healthy test persons was shown. In patients with new ACE inhibitor treatment, heterogeneous reactions of C1-INH values were detected. Larger studies are needed over a longer period of time to find correlations between the effect of ACE inhibitor therapy on C1-INH levels and the clinical course/development of side effects.

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