The Medicines and Healthcare Regulatory Authority (the MHRA) have confirmed that they are investigating reports that suggest that the slimming pill Reductil could be linked to an increased risk of heart problems.

The European Medicines Agency said in December that they were looking into a clinical trial into the slimming pill which seemed to show that the active ingredient in the pills, sibutramine,  could put people at increased risk of developing heart disease.

Since the pill was introduced in 2008, over 300,000 prescriptions have been written for it by GPs around the country. The regulators who set clinical guidelines for the NHS, NICE, have approved it as safe and effective in helping dangerously overweight people shed the pounds and it is widely used across the NHS.

It is one of only two diet pills that are licensed for use in the UK, the other being Xenical, a fat-busting drug manufactured by GlaxoSmithKline, though there are a number of new drugs (such as tesofensine and contrave) which are currently undergoing clinical trials.  . Xenical works to block the action of a fat-digesting enzyme in the gut to dietary fat is not broken down and instead passes out of the body.

Reductil is an appetite suppressant that works by blocking the action of nerve cells that release and then reabsorb serotonin. The hormone serotonin is a chemical neurotransmitter that affects mood and appetite, so as the body’s serotonin levels rise, patients feel fuller and want to eat less.

It is not recommended for use by patients with heart problems, as it is known to slightly raise blood pressure. NICE advise doctors to use the drug with caution and to monitor patient’s heart rate and blood pressure.

The study which has raised concerns is called the Sibutramine Cardiovascular Outcome Trial (SCOUT, for which the research team recruited participants who are overweight or obese and already had heart problems. Over 6 years, an international trial involving 10,000 patients was carried out, though the results by no means prove conclusively that Reductil is dangerous, as the heart problems experienced by the participants would have automatically excluded them from being prescribed the drug.

Nonetheless, the European Medicines Agency said that the ‘seriousness’ of the study had meant they were looking into its implications on the prescription of the slimming pills. They plan to release their findings later this month.

If the drug is banned, it will leave many obese patients without any recourse to medical help. Though there are a number of new slimming pills in the pipeline, such as tesofensine, it will be some time before they are approved and reach the market.

Abbott Laboratories, who manufacture Reductil, said in a statement, “Our ongoing evaluation of the SCOUT study data does not change our medical assessment of sibutramine’s risk/benefit profile when used appropriately in the approved patient population.

“Sibutramine is an important treatment for patients who are obese”.