Current and emerging pharmacotherapies for obesity in Australia

Obesity is a major issue in Australia and globally. Many individuals struggle to maintain weight loss with lifestyle modification, and adjunctive pharmacotherapy may help. Historically, there have been limited pharmacotherapies for managing obesity. In addition, previous treatments such as phentermine-fenfluramine, rimonabant and sibutramine were withdrawn due to safety issues, resulting in lingering safety concerns.

This is a narrative review of published data examining four new pharmacotherapy options for weight management in Australia. Of four new therapeutic options, three may be approved in Australia shortly and one - liraglutide 3.0mg - was approved in December 2015. Liraglutide is a glucagon-like peptide-1 receptor agonist that appears to act by increasing satiety and reducing food intake. Lorcaserin is a selective agonist of the serotonin_2C receptor, which mediates anorectic activity. The naltrexone/bupropion extended release (ER) combination utilises synergistic effects of the two component drugs, mediated via neurons in the hypothalamus, to reduce energy intake. Phentermine/topiramate ER combines the appetite suppressant phentermine with topiramate, an anti-epileptic with appetite-suppressant effects. All can result in meaningful improvements in obesity-related diseases, including diabetes and cardiovascular disorders) in large phase 3 trials, with efficacy demonstrated over 3 years for liraglutide 3.0 mg and 1-2 years for the rest.

The landscape of obesity treatment is changing rapidly. Of the new therapeutic options presented, all options have associated adverse events requiring long-term safety data, but the availability of new options is a welcome development.