Oz scientists tackle side effects caused by commonly used drugs

MELBOURNE - Scientists in Australia have taken a major step in addressing the side effects caused by some of the world’s commonly used drugs.

The issue emerged in the mid-1990s and it has seen nine separate drugs, including an antihistamine, an antibiotic and even a gastric drug, being pulled from availability because of concerns over the same unintended side-effect.

Professor Jamie Vandenberg, from Sydney’s Victor Chang Cardiac Research Institute, said the drugs were known to bind to a specific part of the signalling system, which controls a person’s heartbeat.

“We’ve been aware of this problem now for about 15 years,” the Age quoted Prof Vandenberg as saying.

“These drugs were actually developed to target something else … it might be an anti-psychotic (drug) that will hit a dopamine receptor.

“It then has this off-target effect of blocking this hERG ion channel … which most drugs will stick to it even if they were designed to bind to something else,” he stated.

They could cause cardiac arrhythmias, abnormal electrical activity in the heart, which had the potential for lethal complications.

Anti-psychotic drugs were particularly prone, Prof Vandenberg said, though they remained on the market because there were few alternatives and the benefit for patients was deemed to outweigh the risk.

It is the hERG ion channel that carries and regulates the tiny pulses of electricity, which ensure a healthy heartbeat.

Prof Vandenberg’s research has described the operation of a key part of this channel, a complex “gate mechanism”, which allows these pulses through but was also implicated in the off-target problem.

He said understanding the form and operation of this gate should help in the redesign of existing and the development of future drugs that would avoid, instead of blocking, the channel.

The research has been published in the journal Nature Structural and Molecular Biology. (ANI)