Stirling study shows reduced weight gain in rats

A study conducted for Perth-based Stirling Products (ASX:STI) has shown that its beta agonist ST810 reduced weight gain in obese Zucker rats.

The study was performed by a contract testing facility in the United States on male obese Zucker rats, a common model for weight-loss therapies. Three groups of 16 week old rats were orally dosed, with 1.25 mg or 2.5 mg of ST810, and a control group that received no ST810. The rats had access to feed and water with ST810 administered twice daily.

ST810 (or R-salbutamol) is a single enantiomer form of salbutamol which Stirling is developing primarily for growth promotion in lifestock animals. Other applications include for the treatment of Heaves in horses, a disease similar to asthma, and as an anti-obesity treatment for companion animals.

"What we wanted to do with this study was to provide some early information on the ability of R-salbutamol to reduce weight gain," said Stirling's managing director Calvin London.

The study found that the two groups of rats that received either 1.25 mg or 2.5 mg of R-salbutamol showed significant reduction in weight gain, at 57 and 79 per cent respectively. The control rats gained on average 28 grams of weight.

"We now have data to show that it does reduce weight, in terms of the rate of weight gain, and then once that's under control, the lipolytic activity of this compound will start to actually reduce the fat that's there," said London.

Obesity occurs in about 30 - 40 per cent of companion animals in the United States and Stirling is projecting that its product for companion animals could be on the market sometime in 2008. "A companion animal registration process is not as rigorous as other forms of animal health products, and certainly no where near as rigorous as human applications," said London.

US-based company Sepracor is currently selling R-salbutamolas a treatment for asthma in humans, under the name Xopenex. "In practical terms we know that it's safe and effective because it's already been tried for humans," said London. Stirling has a patented process for the use of R-salbutamol as growth agents and patent applications pending for its use in humans and animals as a treatment for obesity.

While Stirling is focused on a product for the reduction of obesity in companion animals, there is potential for a product to treat obesity in humans. "If it certainly shows potential in companion animals we would be looking to find a partner to develop the human applications, because we don't necessarily want to divert our resources into a single human application at this stage," said London.