Tranexamic acid use in the setting of ACE inhibitor induced angioedema

A Retrospective Cohort Study of Tranexamic Acid Administration for the Treatment of Angiotensin-Converting Enzyme Inhibitor-Induced Angioedema in the Emergency Department

BACKGROUND

Treatment options for angiotensin-converting enzyme inhibitor-induced angioedema (ACEi-AE) are primarily limited to airway monitoring and protection with intubation. The efficacy of tranexamic acid (TXA) in this context remains poorly understood.

OBJECTIVE

Examine outcomes among patients treated with and without TXA for ACEi-AE.

METHODS

A retrospective cohort study conducted in two hospitals examined emergency department patients with suspected ACEi-AE from 2017 to 2021. Primary outcomes included intensive care unit (ICU) admission, intubation, days intubated, time to administration of TXA, surgical airway required, and death in patients that received TXA compared with those that did not.

RESULTS

Of 336 eligible patients, 37 received TXA and 299 did not. ICU admission rate was significantly higher in the TXA group (57%) vs. the no-TXA group (15%), odds ratio (OR) 7.61 (95% confidence interval [CI] 3.69-15.70). There were significantly more intubations in the TXA group (20%) vs. the no-TXA group (5.7%), OR 3.87 (95% CI 1.49-10.08). The median time to TXA administration was 51 min (interquartile range 34-131). The number of days intubated, surgical airway, and 30-day mortality were not significantly different in the TXA group compared with the no-TXA group.

CONCLUSION

TXA use did not improve many of the clinical outcomes involved in the treatment of ACEi-AE. One interpretation of these results may be that TXA use was associated with patients who presented with more severe disease, as TXA use was up to the discretion of the treating physician. Randomized controlled trials are needed to clarify the efficacy of TXA use in ACEi-AE.

Tranexamic acid for angiotensin-converting enzyme inhibitor-induced angioedema

Approximately 0.7% of patients taking angiotensin-converting enzyme inhibitors (ACEIs) develop ACEI-induced angioedema (ACEI-IA). With no approved treatments for ACEI-IA, the risk of complications is concerning. Tranexamic acid (TXA) has the potential to prevent intubations and resolve ACEI-IA by inhibiting the downstream production of bradykinin. In this review, we aim to evaluate the safety and efficacy of TXA use in ACEI-IA. We queried the PubMed database for studies involving TXA for ACEI-IA from January 2003 to January 2023. Seven studies met the study inclusion criteria. Our results demonstrate that TXA may improve angioedema symptoms and prevent intubation. In addition, its availability, low cost, and safety profile support its use for improving the symptoms and complications of ACEI-IA in an emergency setting.

A mechanism for hereditary angioedema caused by a methionine-379-to-lysine substitution in kininogens

ABSTRACT

Hereditary angioedema (HAE) is associated with episodic kinin-induced swelling of the skin and mucosal membranes. Most patients with HAE have low plasma C1-inhibitor activity, leading to increased generation of the protease plasma kallikrein (PKa) and excessive release of the nanopeptide bradykinin from high-molecular-weight kininogen (HK). However, disease-causing mutations in at least 10% of patients with HAE appear to involve genes for proteins other than C1-inhibitor. A point mutation in the Kng1 gene encoding HK and low-molecular weight kininogen (LK) was identified recently in a family with HAE. The mutation changes a methionine (Met379) to lysine (Lys379) in both proteins. Met379 is adjacent to the Lys380-Arg381 cleavage site at the N-terminus of the bradykinin peptide. Recombinant wild-type (Met379) and variant (Lys379) versions of HK and LK were expressed in HEK293 cells. PKa-catalyzed kinin release from HK and LK was not affected by the Lys379 substitutions. However, kinin release from HK-Lys379 and LK-Lys379 catalyzed by the fibrinolytic protease plasmin was substantially greater than from wild-type HK-Met379 and LK-Met379. Increased kinin release was evident when fibrinolysis was induced in plasma containing HK-Lys379 or LK-Lys379 compared with plasma containing wild-type HK or LK. Mass spectrometry revealed that the kinin released from wild-type and variant kininogens by PKa is bradykinin. Plasmin also released bradykinin from wild-type kininogens but cleaved HK-Lys379 and LK-Lys379 after Lys379 rather than Lys380, releasing the decapeptide Lys-bradykinin (kallidin). The Met379Lys substitutions make HK and LK better plasmin substrates, reinforcing the relationship between fibrinolysis and kinin generation.

Bradykinin Metabolism and Drug-Induced Angioedema

Bradykinin (BK) metabolism and its receptors play a central role in drug-induced angioedema (AE) without urticaria through increased vascular permeability. Many cardiovascular and diabetic drugs may cause BK-mediated AE. Angiotensin-converting enzyme inhibitors (ACEIs) and neprilysin inhibitors impair BK catabolism. Dipeptidyl peptidase-IV (DPP-IV) inhibitors reduce the breakdown of BK and substance P (SP). Moreover, angiotensin receptor blockers, thrombolytic agents, and statins may also induce BK-mediated AE. Understanding pathophysiological mechanisms is crucial for preventing and treating drug-induced AE.