Skip to main content

Treating obesity complicated by sleep apnoea

A randomised trial investigating the efficacy of dexamphetamine compared to placebo for treating obesity complicated by obstructive sleep apnoea

The purpose of the study is to investigate:

  • whether dexamphetamine is safe and more effective than placebo for treating obesity complicated by obstructive sleep apnoea over a six month period; 
  • whether weight loss can be sustained for 2 years after ceasing the study drug. 

This study will be conducted over a period of 6 months of treatment followed by a further 2 years of monitoring. The treatment being investigated in this study differs from standard treatment because dexamphetamine is not at present a treatment option for people wanting to lose weight.

If you agree to participate, you will be asked to complete 4 questionnaires to assess your suitability and baseline symptoms.

Once your eligibility for the study has been established, you will be assigned to either dexamphetamine or to placebo (a tablet with no active ingredient) by a random process (like tossing a coin) so that neither you nor the researchers will know which you are taking.

You will be reviewed at 1 week and 1, 3 and 6 months after stopping treatment and after 2 years have elapsed since stopping treatment. Reviews are expected to take 10-15 minutes and will occur at Nepean Clinical School on Derby St across the road from the hospital.

At baseline and at every review the following will be evaluated:

  • Your experience of the effects of study medication (by direct questioning and by your responses to a brief questionnaire, which will take about 5 minutes to complete)
  • Your adherence to the agreed diet and exercise program
  •  Your weight and blood pressure 

Your waist circumference will be re-measured at 6 months, the ECG repeated at 3 months and the blood test, sleep study and ultrasound scan of your heart after 6 months.

You will be asked complete a rating scale relating to your executive functioning (mental efficiency) and to perform a brief (15 minute) computer based cognitive test at baseline, on maintenance dose and after ceasing study medication.

A questionnaire relating to depression will be administered at baseline and subsequently if you develop symptoms of depression.

At the end of the study you will be asked to complete a questionnaire relating to your experience of the study treatment. This will take 10-20 minutes.


You may be eligible to participate in this study if you:

  • are aged 18-70
  • your body mass index (BMI) is 25-60
  • you want to lose weight and you are not currently depressed or taking any medication to treat psychiatric illness.

How to participate

If you are interested in assisting with this important and exciting area of research, please contact the study facilitator: Natalie Gauci on 02 4722 3001 or email