Berotralstat dihydrochloride is a low toxicity, effective, highly specific, second-generation, synthetic and orally active plasma kallikrein inhibitor used for the research of hereditary angioedema (HAE) attacks. Berotralstat dihydrochloride works by blocking the enzymatic activity of plasma kallikrein in releasing bradykinin, the major biologic peptide that promotes swelling and pain associated with attacks of HAE.