While the obesity epidemic is indisputable – as is the consequential health burden on society – the growth in use of antiobesity agents is failing to mirror the burgeoning patient population because of a lack of reimbursement by governments, according to a new report from market analysts Datamonitor.

In the USA, the most obese nation in the Western world, one in three adults is classified as clinically obese. And the UK is not far behind: by 2015, almost 16 million Britons over the age of 20 are forecast to be obese – about the current population of the Netherlands.

While governments are more than aware of the toll of obesity and its co-morbidities such as heart disease and diabetes on their health systems, medicines are not being funded because most health bodies consider obesity a ‘lifestyle’ disease, notes Datamonitor, which believes the consequence of this is that the antiobesity drug development pipeline is unlikely to produce a pharmacological ‘silver bullet’.

With the exception of the UK and Spain, obesity drug sales in Europe have declined in recent years, despite there being more obese people now than ever before. “Conversely, the UK anti-obesity market has expanded significantly over the period of the last four years, representing 17% of the total global market. This steady growth is due to the reimbursement practices in the UK,” notes Datamonitor cardiovascular analyst Evguenia Rossikhina.

In the USA, 85% or more of US health plans currently do not reimburse obesity products, but the US still accounts for 52% of anti-obesity drug sales in the seven major markets. However, total sales in the US anti-obesity drug market declined significantly in the period from 2002 to 2005, in part due to the bad publicity surrounding Meridia in 2002 (which was withdrawn temporarily from the Italian market over long term concerns regarding its cardiovascular safety). This, in turn, had a knock-on effect on other drugs.

Roche and Abbot leading the charge
Currently the leading anti-obesity drugs are Roche’s Xenical (orlistat) and Abbott’s Meridia/Reductil (sibutramine), which Datamonitor forecasts will earn $228 million and $124 million in the seven major markets respectively in 2007. New drugs coming to market, it believes, will have to show superior efficacy and a demonstrable impact on other cardiovascular risk factors and co-morbidities such as diabetes, in order to have a chance at reimbursement.

One such offering is Sanofi-Aventis’ Acomplia (rimonabant), which it expects to file for approval in treating type 2 diabetes in 2009, despite having faced major setbacks in the initial obesity indication. But there is little coming up behind. Of the 42 different products in development in 2006, only nine were in Phase III clinical trials and there were 38 different mechanisms of action. This reflects both the complexity of the disease and the high number of feasible targets to combat extra weight, notes Datamonitor.

“Invariably, there is a lot of attrition in late stage development, with a large number of discontinuations of compounds. In the five years previous to 2007, 56 anti-obesity agents were discontinued,” she says.

A number of the products in development also target diabetes, but Datamonitor has not identified any that will provide a significant improvement on those currently available, Ms Rossikhina points out. “In the absence of a highly effective pharmacological cure, and barring a huge sea change in society’s attitude towards diet and physical activity, governmental and societal initiatives seem to be the only thing standing in the way of the continual expansion of the first great epidemic of the 21st century.”