SINGAPORE : The race to lose weight has taken a new dimension following reports from Hong Kong that the indiscriminate dispensing of the slimming drug phentermine may increase the risk of stroke.

Also available in Singapore, the appetite suppressant is sold under the brand names of Duromine and Panbesy, and had cornered some 77 per cent of the overall prescription diet pill market last year, with more than 6.5 million pills prescribed.

According to this year's International Narcotics Board Report, Singapore ranked fifth on a list of countries with the highest per capita consumption of diet pills — after Brazil, Argentina, South Korea and the United States. Hong Kong was sixth.

Phentermines are only indicated for short-term use in treating obesity and some doctors think that more supervision is required in its use.

Dr Wong Choo Wai, a general practitioner, told 938live: "Some patients have the wrong expectations, so they actually request for it when they don't need it, or take it from their friends. So I think that is the part where maybe more supervision is needed."

The doctor estimates that 30 to 50 per cent of his patients on the drug suffer side effects.

He told TODAY that more education for prescribing doctors should be available, as some may not be familiar with the drug. Phentermine has a chemical structure similar to that of the stimulant amphetamine, which acts on the central nervous system. It is generally not used in public hospitals here.

Although both brands are banned in Britain, they are available here and in the US, approved by the Health Sciences Authority (HSA) and the US Food and Drug Administration, respectively.

"When used strictly as indicated, the risk-versus-benefit profile of phentermine remains favourable," said an HSA spokes-person.

Dr Karina Kho, a general practitioner specialising in obesity, said phentermines are effective as patients on the drug lose an average of 2kg to 3kg a month. She prescribes the drug to patients who do not want to pay more for the other two registered diet pills — Reductil and Xenical.

"But due to the side effects, these patients have to be closely monitored," she said.

The other two drugs also have side effects — Reductil's include palpitation, hypertension and seizures, while Xenical's involve oily stools, the urge to pass motion and abdominal and rectal pain. - TODAY/ra