Soon-to-be-available combination medication may be a viable option for obese Australians seeking to lose weight and maintain the loss, but only if they can manage its adverse effects, according to research published in the Medical Journal of Australia.
A combination of phentermine (a sympathomimetic agent that suppresses appetite) and topiramate (which is used to treat epilepsy and for migraine prophylaxis) has recently been approved in the US as a single-pill medication for use by adults with a body mass index greater than 30kg/m2.
Researchers led by Professor Joseph Proietto from Austin in Melbourne analysed data on patients dispensed phentermine-topiramate between January 2010 and July 2012 to measure cessation rates, adverse events, duration of use, and weight and blood pressure before, during and after use of this combination pharmacotherapy.
Of the 103 patients for whom data were analysed, 61 stopped phentermine-topiramate, with 41 ceasing because of adverse events, including cognitive changes, dry mouth, depression and paraesthesia (tingling, prickling, or burning skin sensations).
Mean weight for the group decreased by 13kg during the first phase of treatment - a very low energy diet - and this loss was maintained by those who were able to continue the combination pharmacotherapy.
"For 30 patients who continued on phentermine-topiramate ... the mean weight decreased by 6.7kg between the end of the very low energy diet and the last observation during pharmacotherapy", Dr Neoh and her coauthors wrote.
"Phentermine-topiramate therapy was not well tolerated", the researchers concluded, but was effective for maintenance of weight loss and ongoing weight loss in those patients who were able to continue taking it.
"Combination pharmacotherapy with phentermine and topiramate may soon be available in Australia."