The submissions mark the beginning of the review process for the Luxembourg pharma's Pulzium (tedisamil). If successful, the drug could be marketed sometime next year, according to Solvay. The drug is designed to treat atrial fibrillation by blocking multiple potassium channels, which then enables the muscles of the upper chambers of the heart (the atria) to contract properly. Sales of antiarrhythmic drugs were in decline by the end of 2005, according to Datamonitor's 'Pipeline Insight: Antiarrhythmics' report, published last year. Many of the drugs suffer from proarrhythmic and toxic side effects and so "it may be sufficient for developmental compounds to demonstrate equivalent efficacy but superior safety profiles to gain market share," said the report. Dr Roger Bickerstaffe at Solvay explained to DrugResearcher.com that the key with drugs of this class is to find a dose high enough for good efficacy but low enough to keep side effects to a minimum. As is often the case with antiarrhythmic drugs, this has led to different doses for males and females. Pulzium is a class III antiarrhythmic drug: that is to say, it blocks potassium channels, including I-Kur, I-K-Ach, I-to and I-K-ATP, explained Bickerstaffe. It also targets I-Kr or human ether-a-go-go (hERG). The inhibition of this target is responsible for some of the side-effects shown by this class of drugs: if hERG is inhibited too greatly, the patient may suffer from Torsade de Pointes - a potentially fatal form of ventricular tachycardia. Describing Pulzium as a niche product, he said: "We see this as a speciality drug for use by experts in a hospital setting. "Some of the cardiologists involved in developing it are really quite on having it. If you talk to doctors, they want more drugs [in this class] because different patients respond differently to each drug and so it is good for them to be able to change." Although Solvay expects the drug to earn a relatively modest amount - less than €100m per year - the company is keen for the drug to be approved "as a service to cardiologists," said Bickerstaffe. The move will also help Solvay build its cardiometabolic drug franchise. These sentiments were echoed by Claus Steinborn, executive vice president of R&D at Solvay, who described Pulzium as a "valuable treatment option" and a "worthwhile addition to the other cardiometabolic treatments we offer". These other treatments include the blockbuster drug, TriCor (fenofibrate), which is marketed in conjunction with Abbott. Without treatment, patients' atrial muscles quiver instead of beat, leaving the lower chambers (ventricles) unable to effectively pump blood out to the body. Since electrical impulses control the beating of the heart and these are, in turn, regulated by ion channels, all antiarrhythmic drugs control ion flux. If Pulzium is approved, the 30 minute intravenous treatment will go up against the generic and orally-available, amiodarone. There are also several other, oral and injected, class III therapies in late stage development. Cardiome submitted a New Drug Application (NDA) for vernakalant to the US Food and Drug Administration (FDA) last December - in conjunction with development partner Astellas Pharma. An oral form of the drug is also in Phase II development. Another drug that could rival Pulzium is Sanofi-Aventis' oral Multaq (dronedarone). Doctors also have the option of using other classes of drugs to treat arrhythmia. Class I drugs interfere with sodium channels, class II drugs are anti-sympathetic nervous system beta blockers and class IV agents affect the AV node.