A new drug that treats hereditary angioedema, a disease that causes life-threatening swelling in blood vessels, shows early promise, according to a group of US researchers.

Hereditary angioedema (HAE) leads to recurrent episodes of swelling caused by fluid leakage from blood vessels in different regions of the body including the face, extremities, gastrointestinal tract or the throat and larynx. If it manifests in areas like the windpipe, HAEs can cause life-threatening blockage of the air passages.

HAEs are usually the result of low levels or poor function of a protein called C1 esterase inhibitor, say researchers from Massachusetts General Hospital in Boston, where one of two recent trials of the drug was conducted.

At present, HAEs are treated with medicines including C1 esterase inhibitor infusions and, for acute reactions, an injectable drug that inhibits an enzyme called kallikrein. Kallikrein blocking injection is administered with extreme caution as it risks life-threatening allergic reactions.

The new drug called icatibant blocks the receptor for a protein called bradykinin. Bradykinin is considered crucial in developing many of the symptoms resulting from HAE such as dilating blood vessels and inflammation.

The researchers found that the new drug icatibant is capable of interfering with bradykinin's normal actions and prevent abnormal swelling in HAEs.

"We have not had many options for treating painful, debilitating and potentially life-threatening attacks of hereditary angioedema, and these studies showed that icatibant improves symptoms and is not associated with any concerning side effects," says Dr. Aleena Banerji, principal investigator for the Massachusetts General Hospital study.

Icatibant, which has already been approved in the European Union, may soon go through the approval process in US too.

Jerini Inc, the developers of icatibant, has conducted the two randomized, double-blind clinical trials involving a total of 130 patients in US as part of filing its regulatory submission to the U.S. Food and Drug Administration.

Data from patient studies conducted in US and Europe showed that icatibant is safe and effective in treating acute attacks of HAE. No serious treatment-related side effects were reported in either trial, according to the findings published in the latest issue of the New England Journal of Medicine.