Hismanal® was the brand name for a drug called astemizole. It was a type of allergy drug called an antihistamine, which prevented allergy symptoms by inhibiting the effects of certain histamine receptors. Hismanal® specifically inhibited the H1 receptor, which is commonly connected to nasal allergy symptoms, such as rhinitis. This drug was taken off the market in 1999 because it caused serious and sometimes life-threatening heart problems in some patients.
Hismanal® prevented allergy symptoms by binding to the H1 receptors, which release a type of histamine that causes such symptoms as itchy skin and inflammation of certain parts of the body. For people with pollen allergies, Hismanal® helped decrease the severity of many of their nasal allergy symptoms. People who took this drug reported fewer incidences of symptoms associated with nose, eye and swelling problems.
This drug generally was not recommended for children under the age 10 because physicians believed the drug would affect children differently and cause adverse effects. Adults and children eligible for the drug were prescribed one pill at least two hours before eating to reduce stomach upset. Taking the drug with food was not recommended, and patients were instructed to wait at least an hour before eating to avoid any additional stomach problems.
As with most antihistamines, Hismanal® caused dry mouth and headache, though it did not cause unusual tiredness or drowsiness, as is commonplace with some antihistamines. In rare instances, it did cause some drowsiness, but never to the extent that was common in other antihistamines. There were also concerns it could cause damage to the heart, due to the way it changed how the heart functioned. In rare instances, it caused a heart attack, which sometimes resulted in death.
Its effects on the heart also affected a person's ability to breathe normally in some instances. This made the drug unsafe for people with serious breathing problems, such as asthma. People with pre-existing heart problems, such as an irregular heartbeat, heart disease or angina had to undergo serious medical considerations before being allowed to take it. There were also indications it could harm a fetus and pass into breast milk, making the drug unsafe for pregnant or breastfeeding women.
In the United States, the Food and Drug Administration (FDA) also found that the drug had dangerous side effects when taken with other prescription medications. When taken with drugs such as protease inhibitors or fluoxetine antidepressants, reactions included heart arrhythmias and anaphylactic shock. The FDA removed the drug from US markets in 1999, and it has been taken off markets in most other countries as well.
