How Saxenda works
Saxenda is based on a human hormone that suppresses appetite, and is self-injected daily. It can be prescribed to people with a BMI of 30 or more, or people with a BMI 27–29 with weight-related conditions such as prediabetes, type 2 diabetes, high blood pressure, high cholesterol or sleep apnoea. It's not subsidised by the PBS, and costs around $400 per month by private prescription.
How effective is it?
In a large 56-week study sponsored by the manufacturer, 63.2% of people taking the drug – in conjunction with a reduced energy diet and increased exercise – lost at least 5% of their body weight, and 33.1% lost more than 10%. The patients had an average starting weight of around 106kg, and lost an average of 8.4kg over the time. There were other health improvements, including blood glucose, blood pressure and cholesterol levels. A group of patients who received only lifestyle modification advice lost 2.8kg on average.
The main side effects are nausea, vomiting, diarrhoea and constipation. Less common, but more serious, side effects include hypoglycaemia (especially for people taking diabetes medication), pancreatitis, gallbladder disease, renal impairment and suicidal thoughts.
Talk to your doctor about whether it's suitable for you. However, at over $5000 per year for an average weight loss of around 5–6kg more than lifestyle counselling alone, the cost vs benefit needs to be considered.
For more on Saxenda see the NPS consumer information leaflet.
What other medicines help with weight loss?
Your main options for weight loss medications in Australia are Xenical (orlistat) and Duromine (phentermine).
Xenical (orlistat) works in your stomach and intestine by preventing your body from absorbing some of the fat you eat, helping to lose weight. Some dietary modification may be needed - if you eat too much fat you may suffer side effects such oily bowel movements and seepage, flatulence, faecal incontinence, diarrhoea and abdominal pain. It's available over the counter for around $120 a month (if taken three times a day). Our article on Xenical has more information.
Duromine (phentermine) is an amphetamine-like drug that helps with weight loss by suppressing appetite. Phentermine side effects include tachycardia, palpitations, insomnia, anxiety and elevated blood pressure. It's not on the PBS, and costs around $100–140 per month.
In the US, phentermine is available in combination with anti-epilepsy drug topiramate (Topamax and generic), which also works as an appetite suppressant. The weight loss in the combination drug, known as Qsymia, is greater than with phentermine alone. While side effects are relatively rare, some are potentially serious, and include headaches, palpitations, insomnia, paresthesia (tingling, numbness, pins and needles), depression and suicidal thoughts. An Australian study of 103 people had 61 drop out, including 41 because they couldn't tolerate the side effects.
Qsymia was rejected in Europe due to safety concerns – in particular the cardiovascular and mental health effects. The combination hasn't been approved by the TGA for weight loss in Australia, though the individual drugs may be prescribed "off label" by a doctor.