Asthma study focuses on blood pressure medication

(CNN) -- The volunteer who died after joining a Johns Hopkins study on asthma was part of a two-phase study involving whether a longtime treatment for blood pressure could help asthma sufferers.

Researchers were trying to determine whether hexamethonium can reduce the ability of lungs to resist the asthma-like effects of methacholine.

The study's first phase involved inhalation of methacholine to constrict the airway, allowing doctors to study how the body reacted. The second phase added hexamethonium or a placebo just before the methacholine.

Hexamethonium, an old blood pressure medicine, has also been used in intravenous anesthesia. It is now considered an experimental medicine.

The informed consent letter said methacholine could cause asthma-like symptoms such as cough and chest tightness, but added that they should disappear on their own in a short period of time. Participants were given a lung spray and told it would get rid of the symptoms in a few minutes.

When healthy patients are exposed to allergens and irritants, their airways narrow just as those of asthmatics do, but they compensate by taking deep breaths which open and relax the airways. When a non-asthmatic sighs or yawns, it forces his or her airways to open and the muscles to relax: Asthmatics don't get that response.

The consent form from the Hopkins trial said, "The goal of the study is to find out how the tubes that carry air into the lungs (the airways) can stay open even when we breathe all types of irritating chemicals. This is something that happens in the normal lung, however the airway of patients with asthma, do get narrow."

Hexamethonium can lower blood pressure, making patients dizzy when they stand up. The effect can last up to three hours, according to the consent form signed by the study participant.

A patient receiving hexamethonium was to have his or her heart and blood pressure monitored. An intravenous line was to be placed in the patient's vein in case medicine was need during the procedure, according to the letter of informed consent.

Pregnant women and people with heart problems, high or low blood pressure, kidney problems or a history of allergies to anesthetic medication were advised not to participate.