THE race is on to develop the magic pill that will keep us all slim.
Two anti- obesity drugs – Reductil (sibutramine) and Xenical (orlistat) – are available to NHS patients who meet strict criteria but an estimated one million others seek prescriptions for weight-loss drugs at private clinics every year.

Figures collected by the Obesity Management Association, a group which represents private weight-loss clinics, show there are more than one million private consultations for obesity management every year in the UK. Over 90% of these patients are prescribed drugs.

The vast majority – over 85% – are prescribed phentermine and diethylproprion. These have an amphetamine-like action and are used to control appetite. Both were withdrawn in 1997 because of safety concerns. They have now been reinstated but are still not recommended for use by the Royal College of Physicians.

Pharmaceutical companies are now competing to develop more effective weight-loss drugs. They are interested in the discovery by scientists at Dundee University that metformin, a natural substance used to treat diabetes, also burns calories and prevents fat from being stored.

Metformin, derived from the French lily plant, has properties that affect the body in a similar way to exercise by triggering an enzyme called AMP-activated protein kinase (AMPK). It has not proved practical to use metformin for weight loss, but pharmaceutical companies are now trying to develop a cost-effective drug that activates muscle AMPK, and which is safe for human consumption

Scientists are also studying the genes which govern energy expenditure and weight control in order to develop the ideal drug. So far, this has led to the discovery of leptin hormone, a protein produced by fat, which tells the brain when the body is full, and the melanocortin hormone, which is believed to enable appetite-monitoring.

Now, researchers at the Rowett Institute in Aberdeen have identified genes in the Siberian hamster which they believe define the animal’s target body weight.



Siberian hamsters adjust their body weight over the course of the year to become fatter in summer and leaner in winter. The rodent’s body weight can vary by as much as 30% according to the season, and this requires precise control of both food intake and energy expenditure. The Siberian hamster sets upper limits of food intake and, hence, weight gain.

Scientists at the Rowett believe their research on the Siberian hamster will tell us what is lacking in the human energy-regulation system that prevents over-consumption.

Professor Peter Morgan, scientific director and chief executive of the Rowett Institute, said: “These genes we have been looking at in hamster models are involved in defining a target body weight. We believe that the genes we have identified may be involved in defining the upper limits of food intake and hence body weight.

“The question is ‘how does the hamster do this and could this knowledge be of use to human obesity?’

“While many humans do not regulate well against body weight gain (hence the dramatic rise in obesity), it is also true to say that not everyone becomes obese,” said Morgan. “We hope that there may be important elements of this system still present in humans which could be therapeutically targeted for the purpose of body weight regulation.”

To qualify to receive the currently most popular anti-obesity drugs, Reductil and Xenical, on the NHS, patients must have lost 2.5kg by dieting and exercise in the month prior to receiving their first prescription. They must also have a Body Mass Index (their weight in kilograms divided by their height in metres squared) of at least 28 and have another serious illness such as diabetes or high blood pressure, or have a BMI of 30 with no other associate illnesses.

Treatment with the drug should only continue after three months if a patient has lost at least 5% of their body weight, and after six months if 10% of their original weight has been lost.



Government figures released last month show that NHS spending on obesity drugs rose 59% to £31 million last year, with £23m of that spent on Xenical alone.

Dr Peter Copp, of GP Plus, a private Scottish GP company with clinics in Edinburgh and Glasgow sees patients who do not qualify for the drugs on the NHS but who are suitable for the treatment.

“We don’t want everyone rushing off to the doctor asking for these drugs but there is a mismatch between what we are telling people about the problems of obesity and their access to effective therapies. These drugs are effective. We have had tremendous successes. One of our patients lost 27kg.

“NHS GPs are obliged to say to patients ‘if you are really serious, go and lose a few pounds and then we will look at the medicines’. But the patients feel they have tried all of that. They are likely to suffer from low self-esteem and lack motivation.

“Patients come to see us from all over Scotland, from Aberdeen, Stirling, Perth, Borders, and Argyll for obesity treatment. They gravitate here from near and far,” said Copp.

“They say ‘I would like to lose weight; I have asked my GP for drugs and been told that I do not qualify’.”

http://www.sundayherald.com/38044