Astemizole was an antihistamine medication discovered in 1977 and later withdrawn from the market due to concerns about side effects. The medication is still available, with strict restrictions, in some regions of the world. It is mostly used today in clinical trials to learn more about potential applications of the medication, although any new uses will have to be balanced against the risk of side effects before deciding whether to approve it for use.
This medication works by binding to histamine receptors, inhibiting inflammatory responses. Doctors prescribed astemizole for treatment of hives, rashes, and severe allergies. The drug was provided in the form of tablets taken on a regular dosage schedule to keep levels of medication in the blood as stable as possible. It is part of a second generation of antihistamine drugs and was known for being long-acting, making it useful for long-term control of allergy issues.
Studies on people using the drug found that it could potentially cause fatal heart arrhythmias as a result of interactions with certain foods and medications that could cause levels of the drug to become dangerously elevated. Although this side effect was rare, the decision to stop marketing the drug and withdraw it from sale was made in the interests of public safety. The development of rare side effects not seen during clinical trials does happen and it is one reason many nations have drug surveillance programs so doctors can report unusual complications and side effects, allowing regulators to step in if a drug appears to be associated with an increased incidence of severe side effects.
Numerous other antihistamine drugs are available as alternatives to astemizole and drug companies are developing many more, as allergies are a very common complaint worldwide. Allergy medications are a high-profit sector of the pharmaceutical industry because of their wide distribution and the desire on the part of many allergy sufferers to find more effective medications, which they are sometimes willing to pay a premium for.
Clinical trials suggest astemizole may also be useful in the treatment of malaria. This is of particular interest to people working on drug resistant forms of malaria, an increasing problem in some regions of the world. These forms do not respond to more conventional treatments and developing a new generation of malaria drugs is critical for managing them. As of 2010, more research on astemizole was needed to see if it was usable as a malaria treatment and to determine if the side effects are worth the benefits.