In an editorial, Editor-in-Chief Dr Graham Jackson, a UK-based Consultant Cardiologist, has called for greater public awareness of the dangers as well as consequences of the counterfeit drugs market.

"Harmful ingredients found in counterfeit medicines include arsenic, boric acid, leaded road paint, floor and shoe polish, talcum powder, chalk and brick dust and nickel.

"In one scheme, Americans buying fake Viagra on the internet were actually helping to fund Middle East terrorism, unknowingly jeopardising the lives of men and women serving in their own armed forces.

"Alarmingly these include fake drugs that could have devastating consequences, like counterfeit medication for potentially fatal conditions like cancer and high blood pressure. Others can include no active ingredients or harmful ingredients like amphetamines," he wrote.

Although some online pharmacies are legitimate, a significant number of them are illegal and operate globally, selling products of unknown content or origin.

"Counterfeit drugs may originate from many different countries, where governments have little or no controls in place, and be then imported into other countries without being inspected.

"In 2004 Pfizer investigated one Canadian online pharmacy and discovered that the domain name was hosted in Korea and registered in St Kitts. Orders placed on the web were dispatched in a plain envelope from Oklahoma City with a non-existent return address," Dr Jackson wrote.

According to the journal, the challenge of combating these criminal and potentially life-threatening activities is a major concern.